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BRAINS AND INTELLIGENCE The EQ or Encephalization Quotient is a simple way of measuring an animal's intelligence. EQ is the ratio of the brain weight of the animal to the brain weight of a "typical" animal of the same body weight.
Assuming that smarter animals have larger brains to body ratios than less intelligent ones, this helps determine the relative intelligence of extinct animals. In general, warm-blooded animals (like mammals) have a higher EQ than cold-blooded ones (like reptiles and fish). Birds and mammals have brains that are about 10 times bigger than those of bony fish, amphibians, and reptiles of the same body size.
The Least Intelligent Dinosaurs: The primitive dinosaurs belonging to the group sauropodomorpha (which included Massospondylus, Riojasaurus, and others) were among the least intelligent of the dinosaurs, with an EQ of about 0.05 (Hopson, 1980).
Smartest Dinosaurs: The Troodontids (like Troödon) were probably the smartest dinosaurs, followed by the dromaeosaurid dinosaurs (the "raptors," which included Dromeosaurus, Velociraptor, Deinonychus, and others) had the highest EQ among the dinosaurs, about 5.8 (Hopson, 1980).
The Encephalization Quotient was developed by the psychologist Harry J. Jerison in the 1970's. J. A. Hopson (a paleontologist from the University of Chicago) did further development of the EQ concept using brain casts of
many dinosaurs. Hopson found that theropods (especially Troodontids) had higher EQ's than plant-eating dinosaurs. The lowest EQ's belonged to sauropods, ankylosaurs, and stegosaurids.
A SECOND BRAIN? It used to be thought that the large sauropods (like Brachiosaurus and Apatosaurus) and the ornithischian Stegosaurus had a second brain. Paleontologists now realize that what they thought was a second brain was an enlargement in the spinal cord in the hip area, perhaps containing fat and nerve tissue. This nerve center may have controlled the animal's hind legs and tail and was larger than the animal's tiny brain.
DINOSAUR DEFENSIVE WEAPONS AND MANEUVERS
Dinosaurs were armed with built-in defensive weapons and behaviors that were used for dealing with interspecies rivalry or as protection from carnivores (meat eaters). These included:
Horns, Claws, and Spikes - Many dinosaurs had deadly, knife-like protuberances that were excellent protection from being eaten (for
example, Triceratops and
Kentrosaurus ). Some sauropods had large thumb claws; these were especially prominent in the young and in juveniles.
Large size - Some adult diplodocids (like Apatosaurus, Diplodocus, Supersaurus, etc.) and other dinosaurs were so large that only the hugest carnivores or packs of carnivores were a danger.
Armored plating (bony plates fused into leathery skin) -
Ankylosaurids (like Euoplocephalus, Ankylosaurus, and Sauropelta) were plated all over the tops and sides of their bodies. Even their eyelids had armor plating. Only their underbellies were unprotected. To kill an Ankylosaurid, a predator would have had to flip over a terribly heavy animal over - not an easy job.
Thick, leathery skin - This would provide only a little bit of protection from predators with sharp, strong teeth like T. rex, Giganotosaurus, and Utahraptor.
Head butting - Pachycephalosaurs (like Pachycephalosaurus, Stegoceras, Wannanosaurus, etc.) and other thick-skulled dinosaurs may used head butting to repel predators. It had long been thought that Pachycephalosaur's thick domes may have been used for ramming rivals during mating and dominance combat, for attracting mates, and as a last-ditch self-defense against predators. Paleontologist Mark Goodwin of the University of California at Berkeley has analyzed many pachycephalosaur skulls (including those of Pachycephalosaurus), finding no evidence of healed scars. Also, under close analysis, the thick skull bone is not rigid and solid, but porous and fragile when put under extreme pressure. ``It's time to kill the myth ... It certainly wouldn't be in their own best interests to ram heads in a fight,'' said Goodwin ``They would have killed each other, and a couple of bowling balls would hardly make good targets.''
Speed - Leaving a fight can be easier and safer than fighting.
Bludgeon-like tail clubs - Ankylosaurids (like Euoplocephalus and Ankylosaurus) had bony tail-clubs that could easily have been used for defense, which would have been useful for these lumbering, plated grazers. Also, some theropods, like Shunosaurus, Omeisaurus and maybe Mamenchisaurus had tail clubs for protection.
Whip-like tail - Some people believe that sauropods may have used their massive tails as a whip to lash at their attackers. This theory seems unlikely given the amount of physiological damage to tail tissue that would be caused by the sudden acceleration near the end of the tail (and the deceleration upon impact). Also, the large sauropods probably grazed on tree leaves, giving them no room to whip their tail around without hitting tree trunks and getting severe tail damage.
SEXUAL DIMORPHISM It is very difficult to determine which fossils were male and which were female. Some paleontologists have theorized that the males of some species may have had larger crests, frills, or other showy structures that were used in courtship displays, mating rituals, and/or intraspecies rivalry (contests among members of the same species, like territorial disputes and mating competition), very much like many modern-day animals. The development of these structures occurs with sexual maturity, so example of juvenile fossils would have little or none of these structures.
Hadrosaurs Originally, fossils very similar to Parasaurolophus but with smaller crests were thought to belong to a separate species of Parasaurolophus. A similar situation existed for Lambeosaurus and many other crested dinosaurs (the lambeosaurine duck-bills) and dome-headed dinosaurs (Pachycephalosaurs). In 1975, the Canadian paleontologist Peter Dodson showed that many of the supposedly separate species of frilled/crested dinosaurs were the females and juveniles of the species. The anatomist James A. Hopson also interpreted the crest and dome sizes as differing in males and females within a species.
Ceratopsians - Many paleontologists believe that the ceratopsians (like Triceratops and Protoceratops) used their horns and frills in territorial disputes, in mating competitions and for attracting females.
Pachycephalosaurs, the dome-headed hadrosaurid dinosaurs, also exhibit sexual dimorphism. The anatomist James A. Hopson realized that crest and dome size differs in the male and female of the species.
DINOSAUR OFFENSIVE WEAPONS AND MANEUVERS
Many dinosaurs were armed with built-in weapons that were used for killing
and eating prey, for dealing with interspecies rivalry, or as protection from fellow carnivores (meat eaters). These included:
Big, sharp, pointed teeth - Largest, sharp teeth of most carnivores are for tearing flesh from prey.
Clawed feet - Many dinosaurs claws on feet and/or hands. Dromaeosaurids and Megaraptor had a huge retractible sickle-like claws on each foot.
Grasping hands with clawed fingers - good for catching and slashing prey.
Large size - Some dinosaurs, like Giganotosaurus and T. rex were so large that they were at the top of the food chain, and could eat any animal that they could catch.
Speed and agility- In order to eat, a predator must catch its prey. The only surviving dinosaurs, the birds, evolved from the speedy, bird-like theropods.
Modern-day birds have excellent good color vision; it is likely that
the bird-like dinosaurs (advanced theropods like the coelurosaurs) also had color vision. This would have helped them find and catch their prey (just as hawks use their acute vision to spot prey).
DINOSAUR REPRODUCTION Very little is known about dinosaur courtship, rivalry, pairing and mating. EGGS Dinosaurs hatched from eggs laid by females after sexual reproduction. The eggs were round or elongated and had hard, brittle shells. Internally, these eggs were similar to those of reptiles, birds and primitive mammals; they contained a membrane (called the amnion) that kept the embryo moist. Some dinosaurs cared for their eggs, others simply laid them and then abandoned them.
The first fossilized dinosaur eggs found (and the biggest yet to be found) were football-shaped Hypselosaurus eggs found in France in 1869. These eggs were 1 foot (30 cm) long, 10 inches (25 cm) wide, had a volume of about half a gallon (2 liters), and may have weighed up to 15.5 pounds (7
kg). The smallest dinosaur eggs are about 1 inch across; they are from Mussaurus.
Many fossilized dinosaur eggs have been found, at over 200 sites in the USA, France, Spain, Mongolia, China, Argentina, and India. Very rarely, the eggs have preserved parts of embryos in them, which can help to match an egg with a species of dinosaur. Without an embryo, it it difficult to match an egg to a dinosaur species. The embryo in an egg sheds light on dinosaur development.
FOSSIL OR ORIGINAL SHELL? According to Dr. Kenneth Carpenter of the Denver Museum, most dinosaur eggshells still have the original shell, not a fossilized replica, "The slightest change in the calcite making up the shell destroys the very fine detail that can be seen with the scanning electron microscope. Amino acids have also been recovered that are very similar to those found in modern bird eggshell."
RECENT FINDS About 10 large dinosaur eggs (plus 3 egg impressions) were found 1999 in southwestern France (near Albas, in the foothills of the Pyrenee Mountains). No bone fossils were found. The eggs had been buried in two layers in the sand. No one knows what type of dinosaur the eggs were.
Much larger egg sites have been found nearby, in northeastern Spain near Tremp, where hundreds of thousands of eggs (of both sauropods and theropods) have been found. Other huge dinosaur eggs sites have been found in Argentina and China.
NESTS
Fossils of dinosaurs' burrows and nests can reveal a lot about their behavior. Nests vary from simple pits dug into the earth or sand to more complicated nests constructed with mud rims. They may appear in large groups or all alone. The nests and the clutches of eggs reveal information about the dinosaur's nurturing behavior.
Many Maiasaura nests have been
found in Montana, USA; nests, eggs, hatchinglings, juveniles, and adults were found in one area. This fossil evidence indicates a high level of
parental care and a very social dinosaur.
HOW DID THE GIANT SAUROPOD LAY THEIR EGGS One of the many unanswered questions about dinosaur reproduction is how the giant sauropods (like Apatosaurus, Diplodocus, and Brachiosaurus) laid their eggs without breaking them. Even if the sauropod squatted while laying eggs, the eggs would be dropped from a height of roughly 8 feet (2.5
m). Some scientists have theorized that females may have had tube that extended from the body for laying eggs (some modern-day turtles have a tube like this).
SIZE OF THE DINOSAURS
Dinosaurs ranged in size from the size of a chicken to well over 100 feet long. Most dinosaurs were somewhere in the middle. The modern-day blue whale is the largest animal that ever lived - it is larger than any dinosaur was. No one knows why some of the dinosaurs (and some other Mesozoic Era reptiles) got so huge and none do today. This is one of the most interesting unanswered questions in paleontology. There are a lot of theories, but some of them are pretty bizarre; none are generally accepted LONGEST The longest dinosaurs were sauropods; they were gigantic, slow-moving, tiny-headed, cow-like plant-eaters from the late Jurassic and the Cretaceous period. They had very long necks which were useful for reaching wide (and
tall) swatches of vegetation. The lengthy neck was counterbalanced by a massive tail. These sauropods are the largest land animals ever discovered:
Supersaurus - 134 feet long (41 m) Argentinosaurus - 115-130 feet long (35-40 m); 80-100 metric
tons Seismosaurus ("Earth-shaking lizard") - 120+ feet long (37
m); +80 tons Ultrasauros - 100+ feet long (30 m), +80 tons Diplodocus - grew up to 90 feet long (28 m). Brachiosaurus - about 85 feet long (26 m), 40 feet tall, and
weighed 70-80 tons.
The biggest carnivores were theropods from the Cretaceous period:
Giganotosaurus carolinii - found in Patagonia, Argentina. 47 feet long (14 m), 8 tons in weight, and 12 feet tall (4 m).
Tyrannosaurus rex - found in North America - 40-50 feet long (12-15 m), 6 tons in weight.
Carcharodontosaurus saharicus - (meaning shark-toothed lizard) found in in Morocco, Africa, by Paul Sereno. It was probably about 45 feet long and had 5 inch long teeth. Its skull (5 feet 4 inches) is larger than T. rex's, but it had a tiny brain cavity (half the size of T. rex's).
TALLEST The tallest dinosaurs were brachiosaurid sauropods; they had front legs that were longer than their back legs and had a giraffe-like stance. They were gigantic, slow moving, tiny-headed, cow-like plant-eaters from the late Jurassic and the Cretaceous period. They had very long necks which were held upright and were useful for reaching wide (and tall) swatches of vegetation. The lengthy neck was counterbalanced by a massive tail. These sauropods are among the largest land animals ever discovered:
Sauroposeidon, a newly-found brachiosaurid from Oklahoma, +60 tons, 60 feet tall.
Ultrasauros - 100+ feet long (30 m), +80 tons, +40 ft tall Brachiosaurus - about 85 feet long (26 m), 40 feet tall, and
weighed 70-80 tons.
SMALLEST Small fossils are found less easily than large fossils. Also, when small animals die, they are likely to be eaten, perhaps whole, by larger animals. The smallest dinosaurs yet discovered are:
Compsognathus, a theropod (meat-eater) 2 feet (60 cm) long, from 145 million years ago. It was the size of a chicken and weighed about 6.5 pounds (3 kg).
Saltopus - a 2 feet (60 cm) long insectivore (insect-eater) from about 200 million years ago. Lesothosaurus - a 3 feet (90 cm) long, fast running, plant-eater from Africa, 200 million years
ago.
ORDER SUBORDER INFRA- ORDER
DINOSAUR FAMILY SOME GENERA TIME
RANGE SIZE
RANGE
Saltopodidae (leaping feet) Saltopus, Eoraptor late
Triassic
2-3 feet (0.7-1 m) long
Staurikosaurids (Southern Cross lizards)
Staurikosaurus late Triassic
6.5-10 feet (2-3 m) long Herrerasauria
Herrerasaurids (Herrera lizards) Herrerasaurus
late Triassic to early Jurassic
7-10 feet (2-3 m) long or more
Coelophysids (hollow form) Coelophysis, Saltopus
late Triassic to early Jurassic
2-10 feet (0.6-3 m) long
Ceratosaurids (horned lizards) CeratosaurusSyntarsus Early-Late
Cretaceous
11.5-20 feet (3.5-6 m) long
Podokesaurids (swift-footed lizards)
Podokesaurus, Syntarsus
Early-Late Jurassic
3-10 feet (1-3 m) long
Abelisaurids (Abel's lizard)
Abelisaurus, Indosaurus
Early-Late Cretaceous
up to 36 feet (11 m) long
Noasaurids (lizards from NW Argentina) Noasaurus Late
Cretaceous8 feet (2.4 m) long
Ceratosauria
Segisauridae (Segi Canyon Arizona lizards)
Segisaurus, Dilophosaurus
late Triassic to Early Jurassic
20 feet (6 m) long
Coelurids (hollow tails)
Coelurus, Ornitholestes
Late Jurassic to Late Cretaceous
4-8 feet (1.2-2.4 m) long
Dryptosaurids (wounding lizards) Dryptosaurus Late
Cretaceous+20 feet (6 m) long
Compsognathids (pretty jaw) Compsognathus
late Jurassic to early Cretaceous
2-3 feet (0.6-0.9 m) long
Oviraptors (egg thieves) Oviraptor Late
Cretaceous6 feet (1.8 m) long
Caenagnathids (recent jawless)
Caenagnathus, Microvenator
Late Jurassic to Late Cretaceous
7 feet (2 m) long
Avimimids (bird mimics) Avimimus Late
Cretaceous5 feet (1.5 m) long
Ornithomimids (bird mimics) Ornithomimus
Late Jurassic to Late Cretaceous
11.5-19.5 feet (3.5-6 m) long
Garudimimids (Garuda mimics)
Garudimimus, Harpymimus
Mid-Late Cretaceous
11.6 feet (3.5 m) long
Dinosaur Skeleton
SKELETAL FEATURES Anatomically, dinosaurs have skeletal features that distinguish them from other archosaurs (crocodilians and pterosaurs). Dinosaurs have reduced fourth and fifth digits on their hands, their feet have three large toes, they have three or more vertebrae composing the sacrum (fused vertebrae by the hip), and have an open hip socket (a three-bone structure). This hip structure gives dinosaurs a posture that positions their legs under their bodies, unlike other reptiles, which have legs that sprawl out to the sides. For more information on T. rex's bones, click here. HIPS Dinosaurs are classified by their hip structure, into the Order Saurischia (meaning lizard-hipped) and the Order Ornithischia (meaning bird-hipped). This division by pelvic (hip) structure is based on their evolutionary tree; early in the Triassic period, dinosaurs branched into these two groups from their ancestor, thecodonts.
Saurischians
Ornithischians
SKULL The dinosaurs were diapsids (as are all reptiles except turtles), animals that had two extra holes in the sides of their skulls. Some Dinosaur Skeletons:
Stegosaurus
Triceratops
Skeleton
Tyrannosaurus rex Skeleton
Brachiosaurus Skeleton
Brachiosaurus was a tall, long-necked
plant-eater.
Skeleton See the bones of this huge, plated plant-
eater.
A plant-eating dinosaur with
three horns and a frill on its head.
The king of the dinosaurs; a huge
meat-eater.
DINOSAUR TAILS Most dinosaurs had large tails that probably had multiple uses, including acting as a:
Counterbalance - most dinosaur tails counterbalanced a long neck or a large, heavy head. Until a few years ago, people thought that dinosaurs dragged their tails on the ground, serving to do little but making locomotion difficult. This seemed pointless and ignored the fact that the large mass at the front of the dinosaur's body (neck and head) had to be counterbalanced or else the animal would tip over!
Tripod leg - The tails of some dinosaurs could be useful in attaining a tripod stance, which was probably used to forage very tall vegetation and for mating.
Help in turning quickly - Some dinosaurs needed to run speedily and to be able to turn quickly, either to catch prey or avoid predators. In order to turn quickly while running, the tail's movement can shift the runner's direction, allowing swift turns.
Bludgeon for protection - Ankylosaurids (like Euoplocephalus and Ankylosaurus) had bony nodules at the end of their tails that could easily have been used for defense, which would
have been useful for these lumbering, plated grazers. Also, some theropods, like Shunosaurus, Omeisaurus and maybe Mamenchisaurus had tail clubs for protection.
Whip for protection - In 1961, the British zoologist R. McNeill Alexander proposed the idea that some sauropods may have used their massive tails as a whip to lash at their attackers. This theory seems unlikely given the amount of physiological damage to tail tissue that would be caused by the sudden acceleration near the end of the tail (and the deceleration upon impact). Also, the large sauropods probably grazed on tree leaves, giving them no room to whip their tail around without hitting tree trunks and getting severe tail damage. In addition, the amount of time to get a nerve message from the head to the base of the tail (a distance of up to 50 feet, 15 m) would delay the attack considerably. Nerve impulses in humans travel at around 3 - 4 meters/second. If dinosaurs could match this rate of transmission, the time for a nerve impulse to travel from the head to the base of the tail would be about 4 - 5 seconds. Add to this the time to start the whip-like motion and the swift meat-eater would probably already have taken a big bite of Diplodocus.
Prehensile appendage - Some people theorize that some dinosaur tails may have been prehensile, able to manipulate objects. The tails may have been used to build nests, move vegetation, etc., much as an elephant's trunk works.
DINOSAUR TEETH
Looking at an animal's teeth can give you a lot of information on how it lived. Dinosaur teeth can tell you a lot about the animal, including the type of food that it ate, how it obtained that food, and how much further digestion was required (did it chew its food, crush it, or just wolf it down?). Teeth are harder than bone and therefore fossilize more readily than bones. Many fossilized dinosaur teeth have been found. Some species of dinosaurs (like Cardiodon, Deinodon, and Trachodon) are known only from fossilized teeth. The number of teeth that dinosaurs had varied widely. Some, like Gallimimus and Ornithomimus, had no teeth. T. rex had 50 to 60 thick, conical teeth. The dinosaurs with the most teeth were the hadrosaurs (the duck-billed dinosaurs), which had up to 960 cheek teeth. Dinosaurs had replaceable teeth; when a tooth was lost or broken, another one grew in to take its place. SAURISCHIANS:
•Sauropods: The plant-eating sauropods (like Apatosaurus, Brachiosaurus, Diplodocus, Supersaurus, etc.) had peg-like or spoon-shaped teeth for stripping foliage but not for chewing. The tough plant material was digested in their huge guts, possibly in fermentation chambers, and frequently with the aid of gastroliths (gizzard stones, which were stones that the animal swallowed) that helped to grind up the leaves and twigs.
•Theropods: Theropods (like T. rex, Giganotosaurus, Carcharodontosaurus, Allosaurus, Spinosaurus, etc.) were meat-eaters that had sharp, pointed teeth for tearing flesh and/or crushing bones. A recent discovery of a Tyrannosaurus rex coprolite (fossilized feces) containing crushed bone indicates that T. rex did indeed crush its food with its strong teeth and powerful jaws.
ORNITHISCHIANS: The herbivorous (plant-eating) Ornithischians and some prosauropods had varied teeth, but mostly had horny beaks and many blunt, leaf-like cheek teeth for nipping and sometimes chewing tough vegetation.
•Stegosaurids: Stegosaurids (like Stegosaurus and Kentrosaurus) had leaf-shaped teeth.
•Hadrosaurs (the duck-billed dinosaurs which included Maiasaura, Parasaurolophus, Edmontosaurus, Lambeosaurus, etc.) had about 960 self-sharpening cheek teeth. They had more teeth than any other dinosaurs. •Iguanodontids: (like Iguanodon, Ouranosaurus, and Probactrosaurus) had teeth similar to those of modern-day iguanas. The rounded, notched crown of the teeth were curved.
•Heterodontosaurus was a small Ornithischian dinosaur that had three different kinds of teeth (hence its name) and a beak. The sharp, cutting
front, upper teeth were used for biting against the horny beak, the cheek teeth were for grinding food, and it also had two pairs of long, canine-like teeth that fit into sockets.
•Ceratopsians , like Triceratops, Styracosaurus, Monoclonius, and others, had toothless beaks that were used to gather their food and many flat cheek teeth which were used to chew tough, fibrous plant material.
•Most dinosaurs, like the Ankylosaurs (which included Ankylosaurus, Sauropelta, Euoplocephalus, etc.), could not chew their food and might have had large fermentation chambers in which the tough plant fibers were digested. Ankylosaurs had teeth that were shaped like a hand with the fingers together.
•Ornithomimids (like Ornithomimus, Ansermimus, Gallimimus, and Struthiomimus) had no teeth, only beaks, with which they ate plants, insects, and small animals.
First Dinosaur Fossil Discoveries Go to a printable version of this page
The first 3 dinosaur fossils led to the recognition of a new group of animals, the dinosaurs.
The first nearly-complete dinosaur skeleton in New Jersey spurs modern paleontology.
People have been finding dinosaur fossils for hundreds of years, probably even thousands of years. The Greeks and Romans may have found fossils, giving rise to their many ogre and griffin legends. There are references to "dragon" bones found in Wucheng, Sichuan, China (written by Chang Qu) over 2,000 years ago; these were probably dinosaur fossils. Much later, in 1676, a huge thigh bone (femur) was found in England by
Reverend Plot. It was thought that the bone belonged to a "giant," but was probably from a dinosaur. A report of this find was published by R. Brookes in 1763. The First Dinosaur Fossil Scientifically Described The first dinosaur to be described scientifically was Megalosaurus. This genus was named in 1824, by William Buckland; Gideon Mantell (not Ferdinand August von Ritgen) assigned the scientific type species name, Megalosaurus bucklandii. Buckland (1784-1856) was a British fossil hunter and clergyman who discovered collected fossils. (Note: the first dinosaur found was Iguanodon, but it was named and described later than Megalodon.)
It was the first dinosaur ever described scientifically and first theropod dinosaur discovered (this is all in hindsight, because the dinosaurs had not yet been recognized as a separate taxonomic group - the word dinosaur hadn't even been invented yet).
The first dinosaur models (life size and made of concrete) were made by Benjamin Waterhouse Hawkins of England in 1854. The first dinosaur used for amusement was a life-size model of an Iguanodon (made by Hawkins) that was used to house a dinner party for scientists (including Richard Owen) at a major exhibition. The invitations to the party were sent on fake pterodactyl wings. The party took place in London, England, in 1854 Other Early Dinosaur Finds
IGUANODON
Gideon A. Mantell (1790-1852) was another early British fossil hunter. He described and named Iguanodon, a duck-billed plant-eater (1825); Iguanodon's teeth and a few bones were found in 1822, perhaps by his wife, Mrs. Mary Mantell in Sussex, (southern) England. Gideon Mantell also named Hylaeosaurus, an armoured plant-eater (1833) , and others.
HYLAEOSAURUS
The Name "Dinosauria" Sir Richard Owen (1804-1892) was a pioneering British comparative anatomist who coined the term dinosauria (from the Greek "deinos"
meaning fearfully great, and "sauros" meaning lizard), recognizing them as a suborder of large, extinct reptiles in 1842.
He had noticed that a group of fossils (which included remains of Megalosaurus, Iguanodon, and Hylaeosaurus) had certain characteristics in common, including:
Column-like legs (instead of the sprawling legs that other reptiles have)
Five fused vertebrae fused to the pelvic girdle.
Owen presented dinosaurs as a separate taxonomic group in order to bolster his arguments against the newly proposed theory of evolution (although Darwin's "Origin of the Species" wasn't published until 1859, the basic ideas of evolution were known, but its mechanisms, including natural selection, were not). Ironically, his work actually helped support the evolutionists arguments.
This new taxonomic name, Dinosauria, and new group of reptiles was only the beginning of a great scientific exploration. Since Owen's time, about 330 dinosaur genera have been described. Every few months (sometimes every few weeks), a new species is unearthed (for recent finds, see Dino News). Paleontologists have varying estimates of how many dinosaur genera existed during the Mesozoic Era; estimates range from about 1,000 to over 10,000. Whatever this number really is, there are a lot of new dinosaurs left to discover!
The First Nearly-Complete Dinosaur Skeleton and First American Dinosaur The first dinosaur fossil found in the US was a thigh bone found by Dr. Caspar Wistar, in Gloucester County, New Jersey, in 1787 (it has since been lost, but more fossils were later found in the area).
In 1800 in Massachusetts, USA, Pliny Moody found 1-foot (31 cm) long fossilized footprints at his farm that were thought by Harvard and Yale scholars to be from "Noah's Raven." Many other dinosaur footprints were been found in New England stone quarries in the early 1800's, but they were thought to be unimportant and were blown up in the quarrying process. Other fragmentary dinosaur bones and tracks were unearthed at this time in Connecticut Valley, Massachusetts.
A Hadrosaur footprint.
The first nearly-complete dinosaur skeleton was discovered by William Parker Foulke. Foulke had heard of a discovery made by workmen in a Cretaceous marl (a crumbly type of soil) pit on the John E. Hopkins farm in Haddonfield, New Jersey beginning in 1838. Foulke heard of the discovery and recognized its importance in 1858. Unfortunately, some of the bones had already been removed by workmen. The skull-less dinosaur was excavated and named by US anatomist Joseph Leidy who named it Hadrosaurus fouki (meaning "Foulke's big lizard"). It was a duck-billed dinosaur (but it is now a doubtful genus because there is so little fossil information about it). The "Haddonfield Hadrosaurus" is on display at the Philadelphia Academy of Natural Sciences.
Leidy's analysis of this Hadrosaur skeleton was thorough; from its anatomy, he wrote imaginitively about the dinosaur's way of life and its death. Leidy wrote, "Hadrosaurus was most probably amphibious; and though its remains were obtained from a marine deposit, the rarity of them in the latter leads us to suppose that those in our possession had been carried down the current of a river, upon whose banks the animals lived." (Quoted from J. Leidy, Account of the Remains of a Fossil Reptile Recently Discovered at Haddonfield, New Jersey. Proceedings Academy of Natural Sciences, Philadelphia, Dec. 14, 1858 pp.1-16.)
This study influenced the popular image of dinosaurs and dinosaur science for years. This beautiful skeleton made dinosaurs come to life in peoples' imaginations and spurred generations of paleontologists.
Tyrannosaurus rex the "Tyrant lizard king"
T. rex was a huge meat-eating dinosaur that lived during the late Cretaceous period, about 85 million to 65 million years ago. T. rex lived in a humid, semi-tropical environment, in open forests with nearby rivers and in coastal forested swamps. The seasons were mild.
Until recently, Tyrannosaurus rex was the biggest known carnivorous dinosaur; Giganotosaurus and Carcharodontosaurus are slightly bigger.
ANATOMY Tyrannosaurus rex was a fierce predator that walked on two powerful legs. This meat-eater had a huge head with large, pointed, replaceable teeth and well-developed jaw muscles. It had tiny arms, each with two fingers. Each bird-like foot had three large toes, all equipped with claws (plus a little dewclaw on a tiny, vestigial fourth toe). T. rex had a slim, stiff, pointed tail that provided balance and allowed quick turns while running. T. rex's neck was short and muscular. Its body was solidly built but its bones were hollow. SIZE Tyrannosaurus rex was up to 40 feet (12.4 m) long, about 15 to 20 feet (4.6 to 6 m) tall. The arms were only about 3 feet (1 m) long. Tyrannosaurus rex was roughly 5 to 7 tons in weight.
The enormous skull was about 5 feet (1.5 m) long. The eye sockets in the skull are 4 inches (10.2 cm) across; the eyeballs would have been about 3 inches (7.6 cm) in diameter. T. rex left footprints 1.55 feet (46 cm) long (although its feet were much longer, about 3.3 feet (1 m) long; T. rex, like other dinosaurs, walked on its toes). It had a stride length of up to 12 to 15 feet (3.7-4.6 m). T. rex may have run at up to 15 mph (24 kph).
TEETH AND JAWS T. rex's jaws were up to 4 feet (1.2 m) long and had 50 to 60 thick, conical, bone-crunching teeth that ranged in size from very small to over 9 inches (23 cm) long. Adult had a variety of sizes of teeth in their jaws at one time, as teeth were broken and new (smaller) ones grew in to replace them. One T. rex was found with some teeth up to 13 inch (33 cm) long. T. rex could eat up to 500 pounds (230 kg) of meat and bones in one bite! Tyrannosaurus rex had a wrap-around overbite; when T. rex closed its mouth, the upper parts of the lower jaw's teeth fit inside the upper teeth.
SKIN Fossilized specimens of T. rex's rough, scaly skin have been found. It was bumpy, like an alligator's skin, and has been described as a "lightly pebbled skin."
HABITAT AND DISTRIBUTION Tyrannosaurus rex probably lived in forests, where its prey (plant-eating dinosaurs) could find plenty of food. T. rex fossils have been found in western North America and Mongolia.
SENSES Sight: T. rex had large visual lobes in its brain that processed visual information. T. rex also had depth perception (since both eyes faced forwards on the front of its skull, and not placed on the sides), but it was not the only dinosaur that had depth perception. In general, predators (hunters) ofter have depth perception to help them hunt
their prey. Animals that are hunted (like the plant-eating dinosaurs) usually have eyes located on the sides of their head (having no depth perception); this lets them see predators approaching from both sides.
Smell: T. rex's brain had a very large area in the brain for processing odors.
TAIL Tyrannosaurus had a stiff, pointed tail (like other Tetanurans [meaning "stiff tail"]). The tail was used as a counterbalance for its enormous head, for agility and for making quick turns. The rear part of the tail was stiffened by interlocking vertebral zygopophyses (interlocking bony structures projecting forwards and backwards from the neural arches, interlocking one vertebra into another). OTHER HUGE MEAT-EATING DINOSAURS Although not the biggest meat-eating dinosaur ever discovered, Tyrannosaurus rex was certainly one of the largest terrestrial carnivores of all time. The recently discovered Giganotosaurus carolinii and Carcharodontosaurus may have been even more enormous.
SIZE COMPARISONS
Why T. rex's weren't great boxers.
Triceratops horridus
"Horrible Three-horned Face"
K-3 level Triceratops Printout to Color
Labeled Triceratops Printout Triceratops Skeleton Printout
Color Triceratops Online Triceratops Questions and
Answers Triceratops Fact Sheet
ANATOMY Triceratops was a rhinoceros-like dinosaur. It walked on four sturdy legs and had three horns on its face along with a large bony plate projecting from the back of its skull (a frill). One short horn above its parrot-like beak and two longer horns (over 3 feet or 1 m long) above its eyes probably provided protection from predators. The horns were possibly used in mating rivalry and rituals. It had a large skull, up to 10 feet (3 m) long, one of the largest skulls of any land animal ever discovered. Its head was nearly one-third as long as its body. Triceratops hatched from eggs. Triceratops was about 30 feet long (9 m), 10 feet tall (3 m), and weighed up to 6-12 tons. It had a short, pointed tail, a bulky body, column-like legs with hoof-like claws, and a bony neck frill rimmed with bony bumps. It had a parrot-like beak, many cheek teeth, and powerful jaws.
WHEN TRICERATOPS LIVED Triceratops lived in the late Cretaceous period, about 72 to 65 million years ago, toward the end of the Mesozoic, the Age of Reptiles. It was among the last of the dinosaur species to evolve before the Cretaceous-Tertiary extinction 65 million years ago. Among the contemporaries of Triceratops were Tyrannosaurus rex (which probably preyed upon Triceratops), Ankylosaurus (an armoured herbivore), Corythosaurus (a crested dinosaur), and Dryptosaurus (a meat-eating dinosaur).
BEHAVIOR Triceratops was probably a herding animal, like the other Ceratopsians. This hypothesis is supported by the finding of bone beds, large deposits of bones of the same species in an area.
When threatened by predators, Triceratops probably charged into its enemy like the modern-day rhinoceros does. This was probably a very effective defense.
REPRODUCTION No one knows how Triceratops reproduced or raised their young, except that they probably hatched from eggs.
INTELLIGENCE Triceratops was a ceratopsian, whose intelligence (as measured by its relative brain to body weight, or EQ) was intermediate among the dinosaurs.
DIET, TEETH, AND ITS POSITION IN THE FOOD CHAIN
Triceratops was an herbivore, a plant eater (a primary consumer). It probably ate cycads and other low-lying plants with its tough beak. Triceratops could chew well with its cheek teeth (like other Ceratopsians, but unlike most other dinosaurs).
Triceratops was hunted and eaten by T. rex. Coprolite (fossilized feces) from a T. rex was recently found in Saskatchewan, Canada by a team led by Karen Chin. This 65 million year old specimen contains chunks of bones from an herbivorous (plant-eating) dinosaur which was eaten by the T. rex. This bone fragment is perhaps part of the head frill of aTriceratops.
LOCOMOTION Triceratops walked on four short legs; it was a relatively slow dinosaur. Dinosaur speeds are estimated using their morphology (characteristics like leg length and estimated body mass) and fossilized trackways. LOCATIONS AND DISCOVERY OF FOSSILS Many Triceratops fossils have been found, mostly in western Canada and the western United States. Paleontologist Othniel Marsh named Triceratops in 1889 - from a fossil found near Denver, Colorado, USA. At first this fossil was mistakenly identified as an extinct species of buffalo. The first Triceratops skull was found in 1888 by John Bell Hatcher. About about 50 Triceratops skulls and some partial skeletons have been found. CLASSIFICATION Triceratops was a late Ornithischian dinosaur, the order of bird-hipped, herbivorous dinosaurs. It was a member of the suborder Marginocephalia, and the family of large, horned, herding herbivores, the Ceratopsians. The ceratopsians were one of the last major group of dinosaurs to evolve, and include Psittacosaurus, Leptoceratops, Pachyrhinosaurus, Montanoceratops, Chasmosaurus, Centrosaurus, Triceratops, Styracosaurus, Protoceratops, and others.
Kingdom Animalia (animals) Phylum Chordata (having a hollow nerve chord ending in a brain) Class Archosauria (diapsids with socket-set teeth, etc.) Order Ornithischia - bird-hipped dinosaurs (plant-eaters) Suborder Marginocephalia - Infraorder Ceratopsia (also called Ceratopia) Family Ceratopsidae Genus Triceratops
SpeciesT. horridus (type species: Marsh, 1889)
There is some disagreement about how many species of Triceratops have been found. Some paleontologists (notably Ostrom and Welnhoffer, 1990) believe there is one species, Triceratops horridus. Others believe that there are two (C. Forster, 1996) or more species, including: Triceratops horridus, Triceratops prorsus, Triceratops albertensis, Triceratops ingens, Triceratops alticornis, and perhaps others. TRICERATOPS ACTIVITIES AND PRINTOUTS
Print out a K-3 level Triceratops info page to color! A Triceratops printout with information and a labelled diagram. A Triceratops skeleton printout. A first-grade level Triceratops addition activity print-out. Triceratops Find It! Quiz to print out for grades 2 to 3. A print-out quiz about Triceratops - Unscramble the answers and see
how much you know about Triceratops! For grades 2-3. A Triceratops math/coloring activity - For second graders. Do 1-digit
addition problems to color a Triceratops scene. A T. rex and Triceratops Activity print-out for beginning readers
(advanced first graders to second graders). Students read and follow the directions to complete a Cretaceous scene.
An on-line quiz about Triceratops - answer the questions and you will unscramble the picture of Triceratops! On-line for grades 2-4.
Triceratops Fact Sheet with a printable version.
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AGATHAUMAS (pronounced ag-ah-THAW-mas ) Agathaumas
(meaning "great wonder") was a ceratopsid resembling Triceratops. This horned plant-eater
dates from the late Cretaceous period. Fossils (only a few bones from the hip area) have been found in
western North America. It was named by
AGE
An age is a unit of geological time which is distinguished by some feature (like an Ice Age). An age is shorter than epoch,
usually lasting from a few millions of years to about a
hundred million years.
paleontologist Cope in 1872. The type species is A. sylvestris. This genus is a nomen dubium.
AGILISAURUS (pronounced AJ-il-eh-SAWR-us)
Agilisaurus (meaning "agile lizard") was a lightly-built dinosaur that was about 3.5-4 feet (1.2-1.7 m) long and weighed roughly
40 kg. This plant-eater lived during the middle Jurassic period, about 170 million
years ago. It was perhaps a hypsilophodontid. A nearly complete
skeleton was found in China. Agilisaurus was named by Peng in 1990. The type
species is A. louderbecki.
AGROSAURUS (pronounced AG-roh-SAWR-us)
Agrosaurus (meaning "wild country lizard") was an ornithischian dinosaur, a primitive prosauropod about 6.5-10 feet (2-3 m) long, weighing perhaps 18-30 pounds (40-70 kg). This small bipedal
plant-eater had a long tail, short arms, and lived during the late Triassic period, about 225-213 million years ago. It was thought to be the first fossil found in Australia, but has since been found to a mislabeled fossil
from Britain (Wales). Only a few bones were found. Agrosaurus was named by Seeley in 1891. The type species is A.
macgillvrayi, but Agrosaurus is a nomen dubium and is probably the same as
Thecodontosaurus antiquus.
ALAMOSAURUS (pronounced Al-uh-moe-SAWR-us)
Alamosaurus (meaning "Ojo Alamo [New Mexico] lizard" ) was a long-necked, whip-
tailed dinosaur about 69 feet (21 m) long and weighed perhaps 33 tons (30000 kg). It was a quadrupedal, plant-eater from New Mexico, Texas, and Utah, USA during the late Cretaceous period, about 73 million to 65 million years ago. It was a sauropod and
a Titanosaurid that may have had some body armor. It was named by Gilmore in
1922. The type species is A. sanjuanensis.
ALBERTOSAURUS (pronounced al-BUR-toh-SAWR-us)
Albertosaurus was a large, meat-eating dinosaur from the late Cretaceous period.
It was a theropod related to T. rex. Albertosaurus was about 8.6 m long and weighed about 2500 kg. The type species
is A. sarcophagus.
ALECTROSAURUS (pronounced ah-LECK-troh-SAWR-us)
Alectrosaurus [meaning "Alectra's lizard," Alectra was one of the furies in classical mythology] was a huge, bipedal, meat-
eating dinosaur from the late Cretaceous period, about 98 million to 88 million years
ago. It was a tyrannosaurid, a theropod
ALGOASAURUS (pronounced al-GOH-a-SAWR-us) Algoasaurus (meaning "Algoa Bay
(South Africa) lizard") is doubtful genus of dinosaurs; it is known from only a few bones found in Africa. This long-
necked, long-tailed plant-eater (a neosauropod and perhaps a titanosaurid)
was about 30 ft (9 m) long. It lived during the early Cretaceous period,
about 145-135 million years ago. The
related to T. rex, but it had larger arms and claws and very long jaws with many teeth. Unlike most tyrannosaurids, its skull was
smooth on top. It was about 25-30 feet (8-9 m) long and weighed perhaps 1.5 tons. It had powerful legs, tiny arms, and a stiff, pointed tail. Partial skeletons have been found in the Gobi Desert in Mongolia.
Alectrosaurus was named by paleontologist C. W. Gilmore in 1933. The type species is
A. olseni.
type species is A. bauri. Algoasaurus was named by the paleontologist Broom
in 1904.
ALIORAMUS (pronounced AL-ee-uh-RAY-mus)
Alioramus, meaning "different branch," was a large, bipedal, meat-eating dinosaur from the late Cretaceous period, about 73 million to 65 million years ago. It was a
tyrannosaurid theropod about 16-20 feet (5-6 m) long, perhaps weighing up to 1 ton. It had 6 tiny horns on its snout; four in a row on the lower snout plus a horizontal pair near the eyes. It had powerful legs, tiny
arms, and a stiff, pointed tail. It had more teeth and a longer skull than other
tyrannosaurids. A single, fragmentary skeleton was found in Mongolia. Alioramus was named by Kurzanov in 1976. The type
species is A. remotus.
ALIWALIA (pronounced ahl-ih-WAHL-ee-ah)
Aliwalia (named for Aliwal North, South Africa) was a carnivorous dinosaur
known from only a few bones found in south Africa. This meat-eater (a
theropod) was about 25 ft (8 m) long and weighed about 1500 kg. It lived during the late Triassic period, about 145-135
million years ago. The type species is A. rex. Aliwalia was named by the
paleontologist Galton in 1985. The type species is A. rex.
ALLIGATOR Alligators are large reptiles. Primitive
alligators evolved during the late Triassic period.
ALLOPATRIC SPECIATION Allopatric speciation is the formation of new species after
a population has been separated geographically. Over time, the two isolated populations diverge genetically. Allopatric speciation is probably the major mode of
speciation (the formation of new species). Compare with parapatric speciation and sympatry.
ALLOPATRY Allopatry means occupying
different geographic locations. Compare with parapatry and sympatry.
ALLOSAURUS (pronounced Al-oh-SAWR-us) Allosaurus, meaning
"different lizard," was a huge, meat-eating dinosaur from the late Jurassic period, about 154 million to 144 million years ago. It was a theropod that lived in what is now the
western United States. It was about 10.5 m long. The
type species is A. fragilis.
ALOCODON (pronounced a-LOK-oh-don) Alocodon (meaning "furrowed tooth") is doubtful
genus of dinosaurs; it is known from only a single tooth. Alocodon was a small,
plant-eating dinosaur of unknown length, perhaps about about 3 feet (1 m) long. It
was an ornithischian from Europe (Portugal) during the late Jurassic period,
about 164 million years ago. The type species is A. kuehni. Alocodon was named
by the paleontologist Thulborn in 1973.
ALPHADON (pronounced AL-fa-don) Alphadon
(meaning "first tooth") was a metatherian, primitive marsupial. It was not a dinosaur,
but lived with the dinosaurs. Alphadon was a small omnivore, eating fruit,
insects, and small animals. It was about 1 feet (30 cm) long. This tree-dweller had
opposable toes and a prehensile tail which it may have used to climb trees. It lived in North America (Alberta, Canada to New Mexico, USA) during the late Cretaceous period, about 70 million years ago. The type species is A. marshi. Alphadon was named by the paleontologist Simpson in
1929. Classification: Subclass Prototheria, Order Pantotheria, Infraclass Metatheria,
Genus Alphadon.
ALTICAMELUS
Alticamelus (meaning "tall camel") is the old name of Aepycamelus. It was a
prehistoric camel that lived from the middle through late Miocene. This giraffe-like
early camel was about 10 ft (3 m) tall at the head; it had a small back hump and a short tail. It had very long legs, and small hooves on its two toes and broad pads. It probably moved in a manner similar to modern-day camels. Fossils of this mammal have been
found in Colorado, USA.
ALTIRHINUS (pronounced al-ti-RINE-us) Altirhinus
(meaning "high snout") was an iguanodontid, a plant-eating dinosaur about about 23-26 feet (7-8 m) long.
Altirhinus had a tall beak on its rounded snout and a spiked thumb on each hand. This big-nosed dinosaur may have had a
good sense of smell. It walked on two long legs but could also eat on all four imbs - the arms were a bit smaller than the legs. It was an ornithischian from Mongolia during the early Cretaceous
period. The type species is A. kurzanovi. Altirhinus was named by the
paleontologist David Norman in 1998. Altirhinus used to be known as
Iguanodon bernissartensis, (Rozhdestvensky, 1952).
ALTISPINAX (pronounced AL-tee-SPY-nax) Altispinax
(meaning "high spine") is doubtful genus of dinosaurs; it is known from only a single tooth. The vertebral material originally
found (which gave this dinosaur its name) has been assigned the name Becklespinax.
Altispinax was a large meat-eating dinosaur of unknown length, perhaps about about 30 feet (9 m) long, weighing roughly 1000 kg.
ALVAREZ, LUIS Luis Alvarez (1911-1988) was a
physicist who, with his son Walter Alvarez (a geologist), hypothesized that the a huge asteroid hit Earth the Earth 65
million years ago, causing a mass extinction. The Alvarez Theory of Extinction is widely accepted. Luis Alvarez received a Nobel Prize in
physics (1968) for his work on
It was a theropod, a bipedal, meat-eating, stiff-tailed predator from Europe (England) during the early Cretaceous period, about
123-119 million years ago. The type species is A. dunkeri. Altispinax was named by the
paleontologist von Huene in 1923.
subatomic particles.
ALVAREZ THEORY OF
EXTINCTION This theory is that a large asteroid, meteor, or comet hit the Earth 65 million years ago, causing huge
atmospheric and geologic disruptions, leading to a mass
extinction which killed the dinosaurs and many other species.
ALVAREZSAURUS (pronounced Al-vuh-rez-SAWR-us)
Alvarezsaurus was a small, lightly-built, bird-like, bipedal theropod (a meat-eating dinosaur) that
was about 6 feet (2 m) long, weighing roughly 20 kg. This fast runner had very long legs, long feet,
very short arms, a long, s-shaped neck, and an extremely long, thin, flat tail. The tail was over half of the dinosaur's length. It had no ridges on
its back, like most other theropods. It lived during the late Cretaceous period, 80 million years ago,
in what is now Argentina. It and the family of Alvarezsaurids were named for the historian Don Gregorio Alvarez by José Bonaparte in 1991. The
type species is A. calvoi.
ALWALKERIA (pronounced al-wah-KEER-ee-a)
Alwalkeria was a small, early theropod (a bipedal, meat-eating dinosaur). It lived during the late Triassic period, roughly 220 million years ago. An incomplete
fossil was found in what is now India. It was named by Chatterjee and Creisler in
1994, honoring the British vertebrate paleontologist Alick D. Walker. The type
species is A. maleriensis.
ALXASAURUS (pronounced AWL-shah-SAWR-us)
Alxasaurus (meaning "Alxa [Desert of Inner Mongolia] lizard") was an advanced theropod (a meat-eating dinosaur) that was
about 11.5-13 feet (3.5-4 m) long and weighed about 800-900 pounds (350 to
400 kg). This bipedal carnivore had long legs with clawed feet, relatively long
arms, a long, s-shaped neck, a toothless beak, and a short tail. Alxasaurus was the most primitive therizinosauroid (bird-like asian theropods with unusual feet). It lived
during the Cretaceous period, about 99 million years ago, in what is now
Mongolia. It was named by paleontologists D. A. Russell and Dong in 1995. The type species is A. elesitaiensis.
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ANAPSID (pronounced an-AP-sid)
Anapsids include the turtles and their extinct kin. They are distinguished by having
no holes in the sides of their skulls.
ANASAZISAURUS
(pronounced ahn-ah-SAH-zee-SAWR-us) Anasazisaurus (meaning "Anasazi lizard") was a plant-eating dinosaur
very similar to Kritosaurus. This hadrosaur was about 33 ft (10 m) long and lived during the late Cretaceous
period. Only a skull was found, in New Mexico, USA. Anasazisaurus was named by Hunt and Lucas in 1993.
The type species is A. horneri.
ANATOMY
Anatomy is the study of structure of organisms.
Anatomists are scientists who study anatomy.
ANATOSAURUS
(pronounced uh-NAT-uh-SAWR-us) Anatosaurus (meaning"duck lizard") is an obsolete name for Edmontosaurus, a
duck-billed dinosaur from the Cretaceous period. Anatosaurus was named by Lull and Wright in 1942; the type species is A. annectens. A. longiceps = Anatotitan
longiceps.
ANATOTITAN
(pronounced un-NAT-uh-TYE-tan) Anatotitan (meaning "giant duck") was a large, duck-billed dinosaur up to 40 feet (12 m) long, weighing roughly
7300 kg. This plant-eater lived during the late-Cretaceous period, 70 million-
65 million years ago in what is now western North America. The type
species is A. copei.
ANCHICERATOPS
(pronounced AN-key-SER-ah-tops) Anchiceratops (meaning "horn-near-face")
was a Ceratopsid dinosaur from the late Cretaceous period, about 73 million to 70
million years ago. This plant-eater was 15-20 ft (4.5-6 m) long and weighed roughly 2470 kg. Anchiceratops was a quadruped. It had a long, rectangular-shaped frill with scalloped edges and a big skull with two long, pointed
brow horns and a stubby snout horn. It is only known from 6 skulls found in Alberta, Canada. This dinosaur was named by fossil
hunter B. Brown in 1914. The type species is A. ornatus.
ANCHISAURUS (pronounced AN-key-SAWR-us)
Anchisaurus (meaning "near lizard") was a prosauropod from the early Jurassic
ANCHISAURIPUS
(pronounced AN-key-SAWR-ip-us) Anchisauripus is an ichnogenus of
dinosaur, a theropod dinosaur only known from fossilized, bipedal, three-toed
footprints (roughly 4 to 7 inches long). This
period, about 200 million to 188 million years ago. This plant-eater was 6.5 to 8
feet (2 to 2.5 m) long and probably weighed from 65-150 pounds (30-70 kg). It was a quadruped that could also walk on two legs. It had serrated, leaf-shaped teeth, a small head, a long neck, a long body, long, thin feet, and a long tail.
Almost complete fossils have been found in Connecticut and Massachusetts, USA.
This dinosaur was named by paleontologist O. Marsh in 1885. The type species is A. polyzelus. It is also
known as Yaleosaurus.
ichnogenus lived in what is now Connecticut, USA during the late Triassic
to early Jurassic period. It was named by R. S. Lull in 1904.
ANDESAURUS
(pronounced AN-di-SAWR-us) Andesaurus delgadoi was a 60-130? feet (18-40 m) long Titanosaurid sauropod that weighed roughly 12500 kg. It was an enormous, long-necked,
long-tailed, quadrupedal, plant-eater from Argentina, South America during the
Cretaceous period, about 113 million to 91 million years ago. Its tail vertebrae, which were ever 2 feet (0.6 m) long, had ball and
socket joints (the same type of joint we have in our hips). Andesaurus, meaning
"Andes mountain Lizard," was named by Calvo & José Bonaparte in 1991. It is
known from vertebrae, arm, and hip bones.
ANDREWS, ROY C. Roy Chapman Andrews (1884-1960)
was a US fossil hunter and director of the American Museum of Natural History.
Andrews led four expeditions to the Mongolia's Gobi desert between 1922 and 1925. Many important finds were made on these expeditions, including
Protoceratops bones and eggs (the first dinosaur eggs found!), and the new dinosaurs Oviraptor, Pinacosaurus, Saurornithoides, and Velociraptor.
ANDREWSARCHUS
(pronounced ANN-drew-SARK-us) Andrewsarchus (named for paleontologist
Roy Chapman Andrews, who led the expedition on which it was found) was a primitive, carnivorous mammal that lived
during the early Eocene Epoch, roughly 45 million years ago. This giant creodont was heavily-built and wolf-like. It was about 13 feet (4 m) long and had a skull over three
feet (1 m) long; it was the largest creodont. It walked on four short legs and had a long body, a long tail, and a long snout. It had
large, sharp teeth and clawed feet. Flat cheek teeth were perhaps used to crush bones.
Fossils have been found in Mongolia; they
ANGATURAMA
(pronounced AHN-gah-two-RAH-ma) Angaturama (meaning "noble one") was
a meat-eating dinosaur, a spinosaurid theropod. It lived during the early
Cretaceous period. Only a partial skull was found, in N.E. Brazil. It was named
by Kellner and Campos in 1996. The type species is A. limai. Angaturama be
the same as Irritator.
were first found in 1923 by Kan Chuen Pao. Andrewsarchus may be an ancestor of the
whales.
ANGIOSPERMS (pronounced AN-gee-oh-sperms)
Angiosperms (meaning "covered seed") are flowering plants. They produce seeds enclosed in fruit (an ovary). They are the dominant type of plant today; there are over 250,000 species. Their flowers are
used in reproduction. Angiosperms evolved about 140 million years ago,
during the late Jurassic period, and were eaten by dinosaurs. They became the
dominant land plants about 100 million years ago (edging out conifers, a type of gymnosperm). Angiosperms are divided into the monocots (like corn) and dicots
(like beans).
ANHANGUERA Anhanguera santanae (meaning "old
devil") was a pterosaur (not a dinosaur). This Pterodactyloid had a skull 1.6 ft (50 cm) long with a small crest on top of the
snout. It had small, widely-spaced teeth in the long, sturdy jaws. Anhanguera had an
estimated wingspan 13.6 feet (4.1 m). Fossils of this flying reptile were found in northeastern Brazil . This carnivore lived
during the early Cretaceous period.
ANKYLOSAURIDS
(pronounced AN-kye-loh-SAWR-ids or ang-KY-loh-SAWR-ids) Ankylosaurids were one division of the ankylosaurs, a
group of armoured, plant-eating, ornithischian dinosaurs with tail clubs and massive legs. Ankylosaurus and Euoplocephalus were ankylosaurids.
ANKYLOSAURS
(pronounced AN-kye-loh-sawrs or ang-KY-loh-sawrs) The ankylosaurs
(ankylosauria) were a group (family) of armoured, plant-eating, ornithischian
dinosaurs from the mid-Jurassic to the late Cretaceous periods. The ankylosaurs are divided into the Nodosaurids (having no
tail clubs, like Sauropelta) and Ankylosaurids (with tail clubs, like
Euoplocephalus).
ANKYLOSAURUS (pronounced AN-kye-loh-SAWR-us or ang-KY-loh-SAWR-us) Ankylosaurus (meaning
"fused lizard") was a heavily armoured plant-eating, ornithischian dinosaur from the
late Cretaceous period. It was named by Barnum Brown in 1908. The type species is
A. magniventris.
ANNING, MARY
Mary Anning (1799-1847) was a British fossil hunter who began finding fossils
as a child, and supported herself and her family by finding and selling fossils.
She lived on the southern coast of England, in Lyme Regis. Anning found
the first fossilized plesiosaur and
Ichthyosaurus. She found many important fossils, including
Pterodactylus, sharks, and many other reptiles and fish.
ANODONTOSAURUS (pronounced an-oh-DONT-oh-SAWR-us)
Anodontosaurus (meaning "toothless lizard" was a small plant-eating dinosaur that actually had teeth, but only in the back of the mouth. It is actually an ankylosaurid, Euoplocephalus
acutosquameus. It dates from the late Cretaceous period, about 76-70 million years
ago. The type species is A. lambei. This doubtful genus was named by Sternberg in
1929.
ANOMOEPUS
Anomoepus intermedius is a dinosaur known only from its fossilized tail prints; these prints are only a few
inches long. This ichnogenus lived during the Triassic period.
Anomoepus was named by E. B. Hitchcock in 1848. Fossils have been
found in Holyoke, Massachusetts, and New Jersey, USA.
ANOPLOSAURUS (pronounced an-OP-loh-SAWR-us) Anoplosaurus
(meaning "no-weapon lizard" was a small iguanodontid dinosaur from the early Cretaceous period, about 98
million years ago. This plant-eater had thumb spikes. A very incomplete fossil was found in England. The type
species is A. curtonotus. This doubtful genus was named by British scientist Harry Govier Seeley in 1879.
ANORBITA FENESTRA
An antorbital fenestra is a hole in the skull
immediately in front of an eye. This fenestra is marks the diapsids.
ANSERIMIMUS (pronounced AN-ser-i-MIEM-us) Anserimimus (meaning
"goose mimic" was an ornithomimid theropod dinosaur from the late Cretaceous period, about 75-70 million years ago. This 3 ft (1 m) long meat-eater was lightly built (weighing about 62 kg), had long legs, short arms with long claws, a
long tail, a long neck, and very few teeth. One skeleton (without a skull) was found in Mongolia. The type species is A. planinychus. Anserimimus was named by Barsold in 1988.
ANTARCTICA Antarctica is an icy continent around the
South Pole.
ANTARCTOSAURUS
Antarctosaurus (meaning "opposite-of-northern lizard") was a giant, long-necked, long-tailed, very
small-headed, quadrupedal, plant-eating titanosaurid sauropod from the late Cretaceous period, about 83 million to 65 million years ago. It had a bulky body,
weak jaws, and had teeth only at the front of the mouth. It was 60-100 feet (19-30 m) long and
ANTHOPHYTA
Anthophyta are flowering plants, the largest group of plants
(which includes the grasses). The flowers are used in
reproduction. They evolved
weighed roughly 57900 kg. Its rear legs were much longer than the front legs. Incomplete fossils have
been found in Argentina, Uruguay, and Chile, South America. Antarctosaurus was found in 1916 and
named by paleontologist von Huene in 1929.
during the Cretaceous period.
ANTIARCHI
Antiarchs (the Antiarchi) were a type of (mosty) small placoderms that were
abundant during mid- to late-Devonian. These armoured fish ranged from 8-12 inches (20-30 cm) long. Instead of the pectoral fins that other fish have, these
unusual tetrapods had segmented "arms" that were covered by hard dermal bone, but these arms lacked an internal skeleton. Arm muscles were attached to the interior of the dermal plates. The "arms" had two joints, at the shoulder and at the elbow (2/3 the way
down from the shoulder) and may have allowed the fish to move in shallow water or perhaps on land briefly. Antiarchi also
differed from other placoderms in that most placoderms had a flexible joint between the
head and thorasic shields, but antiarchs lacked this joint, and the head and thorasic shield were fused together. Bothriolepis,
which fed on organic-rich sediment, was a 20-30 cm long antiarch with auxillary
lungs. Pterichthyodes was a 15 cm Antiarch from the mid-Devonian.
ANTRODEMUS (pronounced AN-truh-DEE-mus)
Antrodemus is an invalid name for Allosaurus. It was a huge, meat-eating dinosaur from the late Jurassic period, about 156 million to 135 million years
ago. It was a theropod that lived in what is now the western United States.
ANURA Anura (or Salienta) is the clade of frogs, toads, and their close fossil relatives. Anura means "no tail," since these amphibians lose their
tail as an adult. The earliest anuran is Triadobatrachus, from the early
Triassic period.
ANUROGNATHUS (pronounced uh-NUR-ugh-NATH-us)
Anurgnathus was a pterosaur, a flying reptile that had a 1 foot (30 cm) wide wingspan, deep, wide, puffin-like jaws and a short tail. It probably ate insects with its peg-like teeth. It lived during the late Jurassic period in what is now Germany. It
was not a dinosaur, but a closely related reptile. It was named by Doederline in 1923.
Ap to Ar
Aa to Af Ag to Al Am An to Ao Ap to Ar As to Az
APATODON (pronounced uh-PAT-uh-don) Apatodon
is a doubtful genus; it is probably an Allosaurus. It was a huge, meat-eating dinosaur from the late Jurassic period, about 156 million to 135 million years
ago. It was a theropod that lived in what is now the western United States.
APATOSAURUS (pronounced uh-PAT-uh-SAWR-us)
Apatosaurus was a huge sauropod from the Jurassic period. It was about 70 to 90 ft (21-27 m) long and weighed roughly
42500 kg. This quadrupedal plant-eater used to be known as Brontosaurus
APOMORPHY
An apomorphy is a new genetic characteristic to a
clade. Feathers are an apomorphy for birds.
AQUATILAVIPES
Aquatilavipes is an early bird known only from its footprints, which are modern looking (not reptilian like
Archaeopteryx). It lived during the early Cretaceous period, about 130 million years ago; these are the oldest-known bird tracks. Fossil footprints have been found in
Canada.
ARAGOSAURUS
(pronounced AHR-ah-go-SAWR-us) Aragosaurus (meaning "Aragón (Spain) lizard") was a large, quadrupedal plant-
eating dinosaur that lived during the early Cretaceous period, about 130-120 million years ago. This sauropod was about 60 ft (18 m) long and weighed about 28000 kg. It had a long neck, a long powerful tail, a
small head, and a bulky body. It was similar to Camarasaurus. A partial fossil
was found in Spain. It was named by Sanz, Buscalioni, Casanovi and Santafe in 1987.
The type species is A. ischiatus.
ARALOSAURUS (pronounced AR-a-lo-SAWR-us)
Aralosaurus (meaning "Aral Sea lizard") was a plant-eating dinosaur that lived
during the late Cretaceous period, about 95-80 million years ago. This sauropod was about 30 ft (9 m) long, and weighed
roughly 5000 kg. It had a toothless beak, a stiff tail, and a bulky body. A partial fossil
was found in Kazakhstan. It was named by Rozhdestvensky in 1968. The type
species is A. tuberiferus.
ARARIPEDACTYLUS Araripedactylus was a pterosaur (not a
dinosaur). This Pterodactyloid had a skull 1.6 ft (50 cm) long and an estimated
wingspan 16 feet (4.8 m). Fossils of this flying reptile were found in northeastern Brazil . This carnivore lived during the
early Cretaceous period. Araripedactylus was described in 1971 by L.I. Price.
ARAUCANORAPTOR Araucanoraptor (which means
"Argentinian Araucan thief") was a meat-eating dinosaur with sickle-like toe claws. It was about 8 ft (2.5 m) long. Fossils of
this coelurosauris theropod were found in Argentina . Araucanoraptor lived during the late Cretaceous period, roughly 90 million years ago. Araucanoraptor was
named in 1997 by paleontologist F. Novas. The type species is A. argentinus.
ARCHAEOCERATOPS (pronounced AHR-kee-oh-SER-a-tops)
Archaeoceratops (meaning "ancient horned-face") is the oldest-known ceratopsian
dinosaur. It lived during the early Cretaceous period, about 95-80 million years ago. A
partial skeleton was found in China. It was named by Dong and Azuma in 1996. The type
species is A. shimai.
ARCHAEOCETE (pronounced AHR-kee-oh-SEAT) Archaeocetes (meaning "ancient
whales") are early whales - whales that lived during the Eocene period
(roughly 55-34 million years ago) . Some archaeocetes include Pakicetus,
Ambulocetus, Basilosaurus, Remingtonocetus, Dorudon, and other early whales, some of which had hind
limbs.
ARCHAEOPTERYX
(pronounced ark-ee-OP-ter-icks) Archaeopteryx (meaning "ancient
wing") is a very old prehistoric bird dating from the Jurassic period, about
150 million years ago. It had teeth, feathers, three claws on each wing, a flat sternum (breastbone), and a long, bony
tail.
ARCHAEORAPTOR
Archaeoraptor liaoningensis (meaning "ancient robber from Liaoning [China]") is a
newly-discovered dinosaur, which was recently found to be a fradulent fossil
created by combining two separate fossils. This turkey-sized theropod was said to have
lived about 120-140 million years ago. It supposedly had hollow bones, feathers, a
long tail, and its shoulder girdle and breast bone were similar to those of modern birds, indicating that it may have been able to fly.
Fossils of this bipedal meat-eater were found in Liaoning Province, China.
ARCHAEORNIS Archaeornis (meaning
"ancient bird"), named in 1917 by Petronievics and
Woodward, is actually Archaeopteryx (the Berlin
specimen).
ARCHAEORNITHOIDES
(pronounced AHR-kee-OR-nith-OI-deez) Archaeornithoides (meaning "Archaeornis-like
[dinosaur]") was a Coelurosaurid dinosaur about 3 ft (1 m) long, weighing roughly 2 kg. This bird-like, meat-eating dinosaur had unserrated teeth. A partial skull of a juvenile Archaeornithoides was found in Mongolia. It
dates from the late Cretaceous period. This advanced theropod was named by Elzanowski and Wellnhofer in
1992. The type species is A. deinosauricus.
ARCHAEORNITHOMIMUS
(pronounced AHR-kee-or-NITH-oh-MIME-us) Archaeornithomimus (meaning "ancient bird mimic") was a small Coelurosaurid dinosaur
about 3 ft (1 m) long, weighing roughly 20 kg. This bird-like, meat-eating dinosaur had three
ARCHAEOZAOIC or
ARCHEAN The Archaeozoic (also called the Archean) was an eon of geologic time during which the earliest life
forms evolved. One celled
fingers, which leads to questions about its being an ornithomimid. A partial skull of a juvenile
Archaeornithoides was found in China. It dates from the late Cretaceous period. This advanced theropod was named by Russell in 1972. The
type species of this doubtful genus is A. asiaticus.
organisms, including blue-green algae, archaeans, and bacteria appear in the sea. This began to free oxygen
into the atmosphere.The Archaeozoic lasted from 3.9 to 2.5
billion years ago. Archaeozoic means "ancient life."
ARCHAEOTHYRIS
Archaeothyris is the oldest-known pelycosaur. This long-tailed quadruped lived
in warm, humid forests of the early-mid Pennsylvanian period, about 300 million
years ago. Archaeothyris looked sperficially like a lizard and was about 20 inches (50 cm) long. This carnivore (meat-eater) had strong jaws and sharp, pointed teeth; it may have
eaten small reptiles like Hylonomus. Fossils have been found in Nova Scotia, North
America. Clasification: Subclass Synapsida, Order Pelycosauris, Family Ophicodontia.
ARCHELON
Archelon was huge marine turtle (a chelonian) that lived during the late
Cretaceous period. It was not a dinosaur. Archelon had a wide,
flattened shell, paddle-like legs, a long, narrow head, weak jaws, and a pointed
tail. It may have eaten jellyfish. Archelon's back probably had a
leathery covering or horny plates over a bony framework on its back. This
carnivore was about 10-13 feet (3-4 m) long. Fossils have been found in Kansas and South Dakota, USA.
ARCHILLOBATOR
Achillobator (Achilles was a Greek hero with a vulnerable heel tendon and bator is
Mongolian for hero) was an advanced meat-eating dinosaur that was about 16 ft (5 m)
long. This large dromaeosaur (deinonychosaur) has a sickle-shaped claw on each foot. This theropod lived during the
late Cretaceous periodA. giganticus.
ARCHIMEDES
Archimedes was a corkscrew-shaped colonial genus of bryozoan named for the ancient Greek Archimedes, who
invented the water screw (the bryozoan looks like the water screw). The marine
bryozoan Archimedes were tubular-shaped zooids with calcified walls. They lived in colonies during the
Carboniferous, roughly 360 to 280 million years ago. Classification:
Kingdom Animalia, Phylum Bryozoa, Class Stenolaemata, Order Fenestrida,
Family Fenestellidae, Genus Archimedes, many species.
ARCHITEUTHIS (pronounced ark-ee-TOO-this) Architeuthis is the giant squid. It is the largest squid and the largest invertebrate (animal without a backbone), but it
ARCHOSAUR
(pronounced ARK-uh-sawr) Archosaurs (meaning "ruling
lizard") were reptiles that dominated the Mesozoic Era.
has never been seen since it lives very deep in the oceans. The largest-known Architeuthis was 57 feet (17.5 m) long. It has eight arms, two longer feeding tentacles, a beak, a large head, and two eyes larger than basketballs! These soft-bodied
cephalopods are fast-moving carnivores that catch prey with their tentacles, then poison it with a bite
from beak-like jaws. They move by squirting water through a siphon, a type of jet propulsion. Only dead examples of Architeuthis have been found. Its only enemy is the sperm whale who
hunts it deep in the ocean.
They included the crocodilians, pterosaurs, thecodonts, dinosaurs
(and birds).
ARCTOSAURUS (pronounced ARK-toh-SAWR-us)
Arctosaurus meaning "arctic lizard" was a meat-eating dinosaur that lived during the late Triassic period. This
theropod was about 10 feet (3 m) long. Fossils of Arctosaurus were found in
Canada . Arctosaurus was described in 1875 by Adams. The type species is A.
osborni, but Arctosaurus is nomen dubium (only neck vertebrae have been found and it may or may not even be a
theropod).
ARGENTINOSAURUS (pronounced ahr-gen-TEEN-oh-SAWR-us)
Argentinosaurus huinculensis was a 130-140 feet (40-42 m) long titanosaurid sauropod. It was an enormous, long-necked, long-tailed,
quadrupedal, plant-eater from Argentina, South America during the Cretaceous period.
Argentinosaurus, meaning "Argentina Lizard," was named by paleontologists Coria & José Bonaparte in 1993. It is known from
fossilized back vertebrae, tibia, ribs and sacrum. It may be the largest dinosaur.
ARGYROSAURUS
(pronounced AHR-ji-ro-SAWR-us) Argyrosaurus (meaning "silver lizard") was a large plant-eating
dinosaur about 70 ft (21 m) long weighing roughly 20000 kg. This massive quadruped. Some limbs have been found in Argentina and Uruguay. It
dates from the late Cretaceous period, about 73-65 million years ago. This sauropod, perhaps an
armoured titanosaurid, was named by Lydekker in 1893. The type species of this doubtful genus is A.
superbus.
ARISTOSAURUS (pronounced uh-RIST-uh-SAWR-
us) Aristosaurus is an invalid name for Massospondylus, an
herbivorous Saurischian dinosaur from the late Triassic period.
ARISTOSUCHUS (pronounced uh-RIST-uh-SUE-kus)
Aristosuchus (meaning "best lizard") is an old (invalid) name for Calamospondylus.
It was a bipedal, meat-eating theropod dinosaur with large hand claws. This
coelurosaur dates from the early Cretaceous period, about 125 million
ARKANSAURUS (pronounced AHR-kan-SAWR-us)
Arkansaurus (meaning "Arkansas lizard") was a bird-like, bipedal, meat-eating
dinosaur (a theropod) that lived during the late Cretaceous period. (It is a coelurosaur
and perhaps an ornothimimid.) This dinosaur is known from foot bones found
years old. This predator was perhaps 6.5 ft (2 m) long, weighing about 65 pounds (30
kg).
in Arkansas, USA. Fossilized foot bones and claws were found in 1972 by J. B.
Friday while looking for a lost cow on his farm near Lockesburg, Arkansas, USA. Arkansaurus was informally named and
described by the geologist James Harrison Quinn in 1973, but this dinosaur has not
been formally described (hence it is a nomen nudum). The type species is A. fridayi (the species name honors J.B.
Friday, who found the fossil and donated it to the University of Arkansas).
ARRHINOCERATOPS (pronounced aye-RYE-no-SER-uh-tops) Arrhinoceratops (meaning "without nose-
horn face") was a ceratopsian dinosaur about 20 feet (6 m) long, weighing roughly 3540 kg. It was a frilled, horned, plant-eater
from the late Cretaceous period, about 72 million-68 million years ago. It is known from a skull found in Alberta, Canada. It
was named by paleontologist Wm. A. Parks in 1925. The type species is A. brachyops.
ARSINOITHERIUM
Arsinoitherium was an early, rhinoceros-like mammal that lived during the early Oligocene (about 38 to 23 million years
ago). Although it looked like a rhinoceros, it is more closely related to elephants. This large quadruped had 5-toed legs. It had 2 huge, conical, hollow horns made of bone on its snout. It was about 11.5 feet (3.5 m) long and about 6 ft (1.8 m) tall at the shoulder. This plant
eater may have lived in forests near rivers. Fossils of Arsinoitherium have
been found in Faiyum, Egypt. Classification: Class Mammalia
(mammals), Subclass Theria, Infraclass Eutheria (placental mammals) Order
Embrithopoda, Genus Arsinoitherium.
ARSTANOSAURUS (pronounced ahr-stahn-oh-SAWR-us)
Arstanosaurus (meaning "Arstan (Kazakhstan) lizard" ) was a lambeosaurine hadrosaur dinosaur (it was originally though to be a ceratopsian) roughly 50 feet (15 m) long. It was a beaked plant-eater from the late Cretaceous period, about 87.5 million-
73 million years ago. It is known from a very incomplete skeleton found in
Kazakhstan. Arstanosaurus was named by paleontologists Suslov and Shilin in 1982.
The type species is A. akkurganensis.
ARTHROPLEURA
(pronounced AHR-throw-PLOOR-ah) Arthropleura was a six-foot long
myriapod (related to millipedes), an arthropod with spines jutting out all
along the sides of its exoskeleton. This jointed animal lived in damp forests
during the Carboniferous (roughly 300 million years ago).
ARTHROPODS
(pronounced AHR-throw-pods) Arthropods are a group of animals with exoskeletons made of chitin,
segmented bodies, and jointed limbs. Insects, arachnids,
trilobites, crustaceans, and others are arthropods.
ARTHURDACTYLUS Arthurdactylus conan-doylensis (named for Sir
Arthur Conan Doyle, who wrote "The Lost World") was a pterosaur (not a dinosaur). This
Pterodactyloid had an estimated wingspan 15 feet (4.6 m); this pterodactyl has wings that were
proportionately longer than any other pterosaur. Fossils of this flying reptile were found in
northeastern Brazil . This carnivore lived during the early Cretaceous period. Arthurdactylus was
described in 1994 by E. Frey and D. Martill.
As to Az Aa to Af Ag to Al Am An to Ao Ap to Ar As to Az
ASIACERATOPS (pronounced AY-zha-SER-ah-tops)
Asiaceratops (meaning "Asian horned face") was a primitive ceratopsian, a quadrupedal, beaked, horned, frilled,
plant-eater from Kazakhstan during the late Cretaceous period, about 97.5 to 90
million years ago. It was about 6-7 ft (2 m) long and weighed about 180 kg. It was
similar to Montanoceratops. Only fragmentary fossils of Asiaceratops have
been found. It was named by paleontologists Nessov and Kaznyshkina
in 1989. The type species is A. salsopaludalis.
ASIATOSAURUS (pronounced AYE-see-at-tuh-SAWR-us) Asiatosaurus (meaning "Asian lizard") was a large sauropod, a quadrupedal plant-eater from Mongolia during the
early Cretaceous period. Only fragmentary fossils of Asiatosaurus have
been found. It was named by paleontologist Henry Osborn in 1924. The
type species is A. mongoliensis.
ASTEROID
An asteroid is a large rock or small planet from the belt that
orbits the sun between Mars and Jupiter. An asteroid impact with the Earth may have caused the
extinction of the dinosaurs.
ASTRODON (pronounced AS-troh-don) Astrodon (meaning "star-tooth") was a long-necked plant-eating
dinosaur, a brachiosaurid sauropod that was about 30? feet (9 m) long (which is small for a
brachiosaurid). It lived during the early Cretaceous period, about 130 million-120 million years ago.
Astrodon is known only from fossilized teeth found in Maryland, USA (Astrodon is the state dinosaur of Maryland). Astrodon was named by
Johnston in 1859. The type species is A. johnstoni. Astrodon may be the same as Pleurocoelus.
ATLANTOSAURUS (pronounced at-LAN-tuh-SAWR-
us) Atlantosaurus ("Atlanta lizard") is a doubtful genus and is
probably Apatosaurus. It was named by Marsh in 1877.
ATLASCOPCOSAURUS (pronounced AT-las-KOP-kuh-SAWR-us)
Atlascopcosaurus (named for the company Atlas Copco [Compagnie Pneumatique Commerciale], that donated some of the equipment for the dig)
was an ornithopod about 6.5 to 10 feet (2 to 3 m) long and weighed roughly 125 kg. It was a plant-
eater that lived during the early Cretaceous period. It is known only from fossilized jaws and teeth
found in Australia. It was named by T. Rich & P. Rich in 1989. The type species is A. loadsi
ATOM
Everything is made up of tiny atoms. An atom is the
smallest part of an element that has the
properties of that element.
ATREIPUS (pronounced ah-TREE-ih-pus) Atreipus is a poorly-known ornithischian (bird-hipped) dinosaur known only from its fossilized tracks. No fossilized bones have been attributed to this ichnogenus. Two sizes of footprints (4.5 and 1 cm long) have been found in conjunction, indicating that this small dinosaur walked on four legs and its rear legs were much larger and longer than the front legs. Atreipus was
roughly 6 feet (1.8 m) long. Trackways were found in Pennsylvania, USA Mike Szajna and Brian Hartline. It lived during the late Triassic period, about 220 million
years ago. The type species is Atreipus milfordensis
AUBLYSODON (pronounced ah-BLEECE-oh-don)
Aublysodon (meaning "backwards tooth") is a poorly-known theropod dinosaur
(perhaps a tyrannosaurid) about 15 feet (4.5 m) long, weighing about 80 kg. It was a meat-eater from the western USA during
the late Cretaceous period, about 76 million-65 million years ago. Its front teeth were long and sharp but not serrated. It was named by paleontologist J. Leidy in 1868.
It is only known from teeth and partial skulls. The type species is A. mirandus
AULAPODUS Aulapodus icels is an ichnogenus, a
dicynodont known from its human-sized footprints, which were made during the Permian period, roughly 255 years ago.
According to paleontologist James Kitching, Aulapodus is Aulacephaledon, a relatively common dicynodont known from the area. The tracks of this plant-eating, tusked therapsid were found in the Karoo near Grahamstown, Eastern
Cape, South Africam which was a marsh during the Permian period. Aulapodus
was named by geologist Billy de Klerk in 1998. The tracks were found by IC ''Ice''
Els, a very perceptive road builder.
AUROCHS (pronounced OR-rox) Aurochs
was a large, wild ox that lived in Europe. This hoofed mammal (an artiodactyl) went extinct in 1627.
AUSKTRIBOSPHENOS Ausktribosphenos nyktos (meaning "Australian
Cretaceous tribosphenic mammal that lived during the night") was a small mammal that lived during
the Cretaceous period, about 115 million years
It was black and had forward-curving horns; it stood about 6 feet
(1.8 m) tall at the shoulder. The aurochs was the ancestor of
domestic cattle. The genus and species are Bos primigenius.
ago. This insect-eater was not a dinosaur, but it lived during the time of the dinosaurs. Its
fossilized jaw was found by Nicola Barton in 1997 at Flat Rocks, southeast of Melbourne, Australia. Ausktribosphenos may have been
nocturnal. It is the oldest-known mammal from Australia, and was neither a marsupial nor a
monotreme (it may have been a placental mammal or a new type of mammal). Ausktribosphenos was
named by Tom Rich and Pat Vickers-Rich.
AUSTROSAURUS (pronounced AW-stroh-SAWR-us)
Austrosaurus (meaning "southern lizard") is a poorly-known sauropod (perhaps a
cetiosaurid) dinosaur about 50 feet (15 m) long, weighing roughly 20000 kg. It was a
plant-eater during the early Cretaceous period, about 113 million-98 million years
ago. Incomplete fossils were found in Queensland, Australia. It was named by
paleontologist J. Longman in 1933. It is only known from teeth and partial skulls. The
type species is A. mckillopi
AUTOTROPH
(pronounced AW-toh-trofe) An autotroph (or producer) is an organism
that makes its own food from light energy or chemical energy (inorganic
matter) without eating. Most green plants, many protists (one-celled
organisms like slime molds) and most bacteria are autotrophs. Autotrophs are
the base of the food chain.
AVACERATOPS (pronounced AY-vuh-SUR-uh-tops)
Avaceratops was a small, horned, frilled ceratopsian dinosaur about 7-14 feet (2-4 m)
long, weighing roughly 1200 kg. It was a beaked plant-eater from Montana during the late Cretaceous period, about 77 million-73
million years ago. It was named by Canadian paleontologist Peter Dodson in 1986. It is
known from partial skulls. The type species is A. lammersi
AVIMIMUS (pronounced AH-vee-MIME-us)
Avimimus (meaning "bird mimic") was a very fast moving, long-legged, bird-
like theropod dinosaur about 5 feet (1.5 m) long, weighing about 14 kg. It was a long-beaked carnivore from Mongolia
during the late Cretaceous period, about 85 million-75 million years ago. It may
have had feathers. It was named by Russian paleontologist Sergei
Mikhailovich Kurzanov in 1981. The type species is A. portentosus
AVIPES (pronounced AH-vee-MIM-us) Avipes
(meaning "bird foot") was a small theropod dinosaur or lagosuchian (reptiles that led to the dinosaurs) with bird-like feet (hence its name). It was a long-beaked carnivore from Germany during the middle Triassic period. It was named by paleontologist von Huene
in 1932. The type species is A. dillstedtianus
AZHDARCHO (pronounced as-DAR-choh) Azhdarcho (meaning "dragon") was a pterosaur, a flying reptile, not a dinosaur. It was a
carnivore that lived during the late Cretaceous period. It is known from fossils found in Uzbekhistan. It was
named by Nessov in 1984.
AZENDOHSAURUS (pronounced ah-ZEN-doh-SAWR-us) Azendohsaurus (meaning "Azendoh [Morocco] lizard") was an early plant-eating dinosaur, a prosauropod about 6 ft (1.8 m) long. It is known only from a partial jaw and some teeth found in Morocco. It lived during the
late Triassic period, about 228 million years ago. It was named by paleontologist Dutuit in 1972. The type species is A. laaroussii
Ta Ta Te Th Ti To Tr Ts-Tu Ty
TANGVAYOSAURUS Tangvayosaurus (meaning "Tang Vay lizard") was a large, long-necked, quadrupedal, plant-
eating dinosaur (an titanosaurid). This tank-like dinosaur was about 6 m long. Talarurus lived
during the late Cretaceous period, about 120 to 99 million years ago. Fossils have been found
in Laos, Asia. Talarurus was named by paleontologists Allian, Taquet, Battail, Dejax, Richir, Veran, Limon-Duparcmeur, Vacant,
Mateus, Sayarath, Khenthavong and Phouyavong in 1999; the type species is T. hoffeti. may be the same as Titanosaurus
falloti.
TALIRURUS (pronounced TAL-a-RU-rus)
Talarurus (meaning "wicker [basket] tail") was a large, armoured,
quadrupedal, plant-eating dinosaur (an ankylosaurid). This tank-like
dinosaur was about 6 m long. Talarurus lived during the middle Cretaceous period, about 99 to 90
million years ago. Fossils have been found in Mongolia, Asia. Talarurus was named by Maleev in 1952; the type species is T. plicatospineus.
TANIUS (pronounced TAN-ee-us) Tanius was a large, crestless Hadrosaurid from China. These heavily-built
plant-eaters were duck-bills that had a bony protuberance between the
eyes on their flat head. Tanius had a toothless beak and strong jaws with
self-sharpening cheek teeth (for chewing tough plant material). It had four-fingered hands and could walk on 2 or 4 legs. Tanius dates from the late Cretaceous period, about 88.5 to
65 million years ago. Tanius was named by Carl Wiman in 1929, after
the "Tanka" people of southern China.
TANYSTROPHEUS (pronounced TAN-ee-STRO-fee-us)
Tanystropheus was a long-necked reptile (not a dinosaur) that dates from the middle Triassic
period. It looked like a lizard with a ridiculously long neck. Its neck was 10 feet (3
m) long, longer than its body and tail put together. Some of the 10 neck vertebrae (neck bones) were over 1 foot (30 cm) wide. It had 4 legs, a tail, and was about 20 feet (6 m) long.
This fish-eater had peg-like teeth. Tanystropheus may have spent a lot of time on the water, but it was neither well adapted for swimming nor walking. It may have lived on the shore and fished with its long neck and
head! Fossils of Tanystropheus have been found in Europe and the Middle East. It may have
been related to the Nothosaurs. Classification: Order Squamata (lizards and snakes).
TAPEJARA (pronounced TAP-ah-JAR-ah) Tapejara
(meaning "old being" in Tupi) was a pterosaur that dates from the early Cretaceous
period, about 132 to 100 million years ago. This flying reptile ate fish and lived near the sea. A Pterodactyloid, it had a wingspan of
about 16.5 feet (5 m) and a short tail. It had a large head crest formed by skin stretched between two bony crests on its head, one
above the nostrils, the other behind and above the eyes. The tip of its lower jaw turned downward. Fossils have been found in
Northeast Brazil. Tapejara was named by Kellner in 1989. The type species is T.
wellnhoferi.
TAPHONOMY Taphonomy (which means 'laws of
burial') is the science that studies the process of decay and fossilization. The
Russian paleontologist Ivan A. Efremov coined the term taphonomy
and founded the study of taphonomy in 1940.
TARBOSAURUS
(pronounced TAR-bow-SAWR-us) Tarbosaurus is an invalid name for
Tyrannosaurus bataar or T. efremovi, Asian theropods smaller than Tyrannosaurus rex. T.
bataar was about 30 to 40 feet (9 to 12 m) long and weighed 4 to 5 tons. T. efremovi was
about 23 to 26 feet (7 to 8 m) long and weighed 2 to 3 tons. Both adult and juvenile skeletons have been found. It was named by
Maleev in 1955.
TARCHIA (pronounced TAHR-key-ah) Tarchia
(meaning "brainy one") was an armoured, plant-eating dinosaur that
dates from the late Cretaceous period, about 78-69 million years ago. This
ankylosaurid ankylosaur was about 18 feet (5.5 m) long and weighed roughly
10,000 pounds (4500 kg). It had spikes running along its sides and at
the corners of its mouth. This lumbering quadruped had a large tail
club and a large braincase. Seven fossils have been found in Mongolia. Tarchia was named by Maryanska in 1977. The type species is T. gigantea.
TAR PIT A tar pit is a pool of gooey asphalt. It is created when crude oil seeps
up from deep inside the Earth through a crack (called a fissure) - millions of years of time and intense pressure convert ancient
organisms, like plankton, into oil. The less dense elements of the crude oil evaporate, leaving asphalt (a very sticky mess). Water pools on the
tar, attracting thirsty animals. As an animal gets stuck in the tar, it attracts predators, who also get stuck. The animals' bones, teeth, and other hard parts are well-preserved in this environment (but they turn
brown from the asphalt). Tar pits are located around the world. A famous tar pit is the Rancho La Brea Tar Pits (in southern California,
USA).
TARSALA tarsal is an ankle bone.
TAXON A taxon is category in the classification of living organisms. The taxa (the plural of taxon) in the
Linnean system are kingdom, phylum, class,
TAXONOMY
order, family, genus, and species. Taxonomy is the science of classifying organisms into groups
by structure, origin, common ancestor, etc.
Tr Ta Te Th Ti To Tr Ts-Tu Ty
TRACE FOSSILS
Also known as ichnofossils, these are fossilized footprints, nests, dung, gastroliths, etc.,
but not actual body parts. They record the movement and behavior of animals.
TRACHODON (pronounced TRACK-oh-don) Trachodon (meaning
"rough tooth") is a plant-eating dinosaur that is known only from a few teeth and parts of the jaw that were
found in Montana, USA. It dates from the late Cretaceous period, about 77-73 million years ago.
From the teeth, it has been surmised that it was probably a duck-billed dinosaur (a lambeosaurine
hadrosaur). Trachodon was named in 1856 by Joseph Leidy; the typs species is T. mirabilis. This is a
dubious genus due to the sparsity of fossils.
TRACKWAYS Many animal track fossils (fossilized
footprints) have been found. They can indicate the animal's speed, weight, and herding behavior.
Determining which animal made the tracks can be difficult.
TRANSGRESSION
Transgression is the flooding of a continent as the sea level increases, usually caused by
melting polar ice. Another cause is sea floor spreading and underwater volcanism, in which large amounts of underwater lava cause water
to be displaced onto land.
TREE FERN
Tree ferns are tall vascular plants that live in warm climates. These ferns have a clump of fronds on
top of a fibrous trunk.
T. rex
(pronounced TEE recks) Tyrannosaurus rex (meaning "tyrant lizard king") was a huge, meat-
eating theropod dinosaur from the late Cretaceous period.
TRIADOBATRACHUS
Triadobatrachus massinoti is the earliest-known salientian, a proto-frog. Morphologically, it is
between a salamander and a frog. This 4 inch (10 cm) long amphibian lived during the early Triassic
period, about 250 million years ago. A single fossils was found in Madagascar. Triadobatrachus had long jumping hind legs and a well-developed eardrum. It had a short body, a short tail, and 14 back vertebrae
(compared to 5 to 9 vertebrae in modern frogs). Classification: Order Proanura.
TRIASSIC PERIOD (pronounced tri-ASS-ik PEER-ee-ud) Dinosaurs and mammals
evolved during the Triassic period, 248 - 208 million years
ago.
TRICERATOPS (pronounced tri-SER-uh-tops)
Triceratops was a frilled dinosaur, a ceratopsian, from the late
Cretaceous period that had three horns on its head. This plant-eater
was about 25 feet (8 m) long.
TRICONODONT
Triconodonts (meaning "three-coned teeth") were small, early mammals that lived from the
Triassic period until the Cretaceous period (from about 200-100 million years ago). These long-tailed, quadrupedal mammals had three-cusped
teeth (hence their name) and ranged from a just a few inches long to the size of a cat. They had
relatively advanced, grasping hands, but a primitive pelvis and hind limbs. These
insectivores may have had large eyes, and may have been nocturnal (most active at night). The most complete triconodont, the 5 inch long, 125
million-year-old Jeholodens jenkinsi, was recently found in Lianong, China.
TRIGONIAS
(pronounced tri-GO-nee-us) Trigonias was one of the earliest rhinoceroses. It lived during the early
Oligocene Epoch, about 35 million years ago. This large, plant-eating mammal was about 8 ft (2.5 m) long, had five-toed front feet, and had more teeth than modern-day rhinos. It did not have a snout
"horn," as modern-day rhinos do. Fossils have been found in Europe (France) and western North
America (Montana). The type species is Trigonias osborni. Classification: Order Perissodactyla (odd-
toed ungulates), Suborder Ceratomorpha (tapirs,
TRILOBITE
(pronounced TRI-low-bite) Trilobites were early
invertebrates with a segmented body and an exoskeleton. Trilobites dominated the environment during the
Cambrian Period (540 to 500 mya).
rhinos), Family Rhinocerotidae, Genus Trigonas. Photo courtesy of Jim Puckett.
TRIMUCRODON Trimucrodon (meaning "triply-pointed
tooth"), Trimucrodon was a small plant-eating dinosaur that lived during the late
Jurassic period, roughly 150 million years ago. A fossilized tooth of this
ornithischian dinosaur have been found in Provincia do Estremadura, Portugal. The type species of this genus is T. cuneatus, named by Thulborn in 1973. Due to the lack of fossil information, this genus is a
nomen dubium.
TRIOLOPHODON
Trilophodon (meaning "three crested tooth") was an ancient mammal that lived
during the Miocene - it is sometimes called Tetrabelodon. This large Gomphothere
was an ancestor of mastodons. Trilophodon was about 5 m long and 2.5 m
high. It was a heavy, plant-eating animal that walked on four column-like legs. It
had a large skull, and elephant-like proboscis, four parallel tusks (two on the top jaw, two smaller ones on the bottom jaw), high-ridged grinding teeth, and a short tail. Fossils have been found in
Europe (France), Africa (Kenya), Asia (Pakistan), and North America (Nebraska, South Dakota). Classification: Kingdom
Animalia, Phylum Chordata, Class Mammalia (mammals), Order Proboscidea,
Suborder Elephantiodea (elephants, mastodonts, mammoths), Family
Gomphotheriidae, Genus Gomphothere.
TRIONYX
(pronounced triI-ON-iks) Trionyx is a genus of soft-
shelled turtles that first appeared during the
Jurassic period.
TRIOPS
(pronounced TRI-ops) Triops (Triops longicaudatus) are small, freshwater crustaceans (often found in rice fields)
that look a little like trilobites. Also called tadpole shrimp, they are branchiopods with a hard exoskeleton, and sturdy
mandibles (jaws). They eat animals and plants, and are sometimes cannibalistic. Their life span is about 20 to 40 days. Triops evolved during the Devonian period, about
350 million years ago (long before the dinosaurs appeared).
TROCHANTER
The trochanter is a bony bump on the femur (the thigh bone) to which large muscles
are attached.
TROÖDON
(pronounced TROH-oh-don) Troodon was a very smart, human-sized, meat-eating theropod dinosaur
from the late Cretaceous period, about 76 to 70 million years ago. Fossils of Troodon have been found in
Montana, Wyoming (USA) and Alberta (Canada). The type species is T. formosus.
TROPEOGNATHUS Tropeognathus (meaning "keel jaw") was a pterosaur that lived during the middle Cretaceous period, about 122 to 112 million years ago. This flying reptile ate
fish and lived near the sea. A Pterodactyloid, it had a wingspan of about 20 feet (6.2 m) and a short tail. The skull was 2.2 feet (67 cm) long. Tropeognathus had a large beak that was enlarged at the tip; it had many sharp teeth. Fossils have been found in the Santana Formation in norteastern Brazil. Tropeognathus was named by Wellnhofer in 1987. The type species is T.
mesembrinus.
TROPHIC LEVEL
A trophic level is a level of the grazing food chain. For example, plant-eaters are primary consumers; they
occupy the second trophic level in the grazing food
chain.
TSINTAOSAURUS (pronounced sin-tau-SAWR-us) Tsintaosaurus is a
genus of plant-eating, duck-billed dinosaurs (hadrosaurs) of which little is known. Tsintaosaurus
was roughly 33 ft (10 m) long. It may have had a thin, hollow bony crest on its head (jutting forwards, or maybe backwards) but some paleontologists think
that this crest may in fact be an artifact of the fossilization process (Tsintaosaurus may be a
lambeosaurine, a crested hadrodaur). Tsintaosaurus lived during the late Cretaceous period. Tsintaosaurus
was named by Young Chung Chien in 1958. Tsintaosaurus means "Tsintao lizard", named for the
city of Tsingtao (Ch'ing-tao or Qingdao, which means "green island") near where the fossil was found in the
Wangshi Formation, Shandong Province, China. Tsintaosaurus may be the same as Tanius (which was named earlier and therefore retains its name), which was a crestless Hadrosaurid from China. Tanius was
named by Carl Wiman in 1929.
TSUNAMI
(pronounced sue-NAHM-ee) Atsunami is a huge wave, caused
by undersea earthquakes, volcanic eruptions, or, more
rarely, by asteroid or meteoroid impact (as in the case of the K-T extinction).
TULLY MONSTER The Tully monster (Tullimonstrum gregarium) was a soft-bodied sea animal with a long proboscis that ended in a "jaw" with eight small, sharp teeth. Tullimonstrum was an
active swimmer that was a carnivore (meat-eater). It lived roughly 280 to
340 million years ago, during the Carboniferous period. Fossils of this unusual organism were first found
by Francis Tully in Illinois, USA, in 1958. It was named and described
TUOJIANGOSAURUS (pronounced Too-oh-gee-ANG-oh-SAWR-us)
A stegosaurid, a quadrupedal, plant-eating dinosaur about 23 feet (7 m) long with double
rows of plates along its back, a toothless beak, a long, low-hanging head, spoon-shaped teeth, 2 shoulder spikes, and a 4-spiked tail. It was from the late Jurassic period, about 163-150 million years ago in China. It was named in 1977 by
Shiwu Zhou, Dong, Zhang, and Li.
scientifically by Dr. Eugene Richardson.
TURTLE Turtles are anapsids, having no extra holes in the sides of their heads. Turtles evolved during the late Triassic period, roughly 220 million years ago, about the same time the
dinosaurs and mammals evolved. Proganochelys is the oldest known turtle. Other early turtles include Proterocheris, Saurischiocomes, Chelytherium, Dermoschelys,
Notoemys, Platychelys, Trionyx, Baena, Chisternon, and Meiolania
DINOSAUR INFORMATION PAGES: A A B-C D-G H-L M N-O P-R S T U-Z Non-Dinos
There are about 1,000 described dinosaur genera. Below is a sampling of dinosaurs. Just click on a dinosaur to go to an information sheet. The drawings are not to scale. For a page on how to write a great dinosaur report, click here. If the dinosaur (or other prehistoric animal) you're interested in isn't here, check the Dinosaur Dictionary for information.
ACANTHOPHOLIS
ACROCANTHOSAURUS
ALBERTOSAURUS
ALLOSAURUS
AMARGASAURUS
ANATOTITAN
ANKYLOSAURUS
APATOSAURUS
AVIMIMUS
Dinosaur Coloring/Information Printouts: A A B C D E-H I-K L-M N-O P-R S T U-Z Non-DinosAlso see our detailed dinosaur information pages and our brief dinosaur fact sheets (with printable versions).
Click on a dinosaur's name to go to a black-and-white print-out. These activities are designed as academic print-outs, for making a dinosaur book, for cut-outs used in dinosaur crafts, for coloring, for stencils, and other uses. For a long version with all the dinosaurs on one page, click here.
Acrocanthosaurus A huge, spine-backed
meat-eater.
Alamosaurus A huge, long-tailed, long-necked, armoured, plant-
eating dinosaur.
Alamosaurus
(Simple Version)A long-tailed, long-
necked, armoured plant-eater.
Albertosaurus A meat-eating dinosaur, a
tyrannosaurid from the late Cretaceous period.
Allosaurus The biggest meat-
eating dinosaur from the late Jurassic
period.
Alxasaurus A meat-eating
dinosaur found in Mongolia.
Anchisaurus A plant-eating dinosaur, a late prosauropod, from the early Jurassic period.
Ankylosaurus A heavily armoured
plant-eater with a club-like tail and spikes.
Ankylosaurus (Simple Version)
A heavily armoured plant-eater with a club-
like tail and spikes.
Apatosaurus A huge, long-necked, whip-tailed plant-eating dinosaur; it used to be known as
Brontosaurus.
Apatosaurus (Simple version)
A long-necked plant-eater; it used to be known as
Brontosaurus
Dinosaur Coloring/Information Print-outs: B A B C D E-H I-K L-M N-O P-R S T U-Z Non-DinosAlso see our detailed dinosaur information pages and our brief dinosaur fact sheets (with printable versions).
Click on a dinosaur's name to go to a black-and-white print-out. These activities are designed as academic print-outs, for making a dinosaur book, for cut-outs used in dinosaur crafts, for coloring, for stencils, and other uses.
Bagaceratops Printout
A plant-eating dinosaur with an armoured head.
Barosaurus A huge, long-necked, whip-tailed plant-eater
from the Jurassic period.
Baryonyx A large meat-eater from
the early Cretaceous period.
Brachiosaurus A huge, long-necked, plant-
eating dinosaur with a giraffe-like stance.
Brachiosaurus(Simple version)
Brachiosaurus Skeleton
A tall, long-necked plant-eater.
Brachiosaurus was a tall, long-necked plant-eater.
SHARKS
SHARK AND RAY INFORMATION SHEETS There are about 350 different species of sharks, which are divided into 8 orders and 30 families. Below is a sampling of shark species. Just click on a shark to go to that information sheet. The drawings are not to scale.
ANGELSHARK
BASKING SHARK
BLACKTIP REEF SHARK
BLUE SHARK
BLUNTNOSE SIXGILL SHARK
BONNETHEAD SHARK
BULL SHARK
DOGFISH SHARK
BROADNOSE SEVENGILL SHARK
GALAPAGOS SHARK GOBLIN SHARK
GREAT WHITE SHARK
LEMON SHARK
MANTA RAY
HAMMERHEAD SHARK
MAKO SHARK
NURSE SHARK
PORBEAGLE SHARK
SPINED PYGMY SHARK
THRESHER SHARK
TIGER SHARK
WHALE SHARK
Shark and Ray Print-outs Click on a shark's name to go to a simple black-and-white print-out. These activities are designed as simple academic print-outs, for making a shark book, for cut-outs used in shark crafts, for coloring, for stencils, etc.
Angelsharks Bottom-dwelling, relatively
harmless sharks with flattened bodies and a blunt
snout.
Atlantic Sharpnose SharkA harmless requiem shark with a sharp
snout.
Basking SharkA huge filter feeder
and the second largest fish.
Basking Shark (Simple version)
A huge filter feeder and the second
largest fish.
Blue Shark A sleek, fast-swimming
shark with blue skin.
Bull Shark A blunt-nosed, dangerous,
gray shark that can also live in fresh water rivers and
lakes.
Bull Shark (Simple version)
A blunt-nosed, dangerous, gray shark can live in fresh water
rivers and lakes.
Cookiecutter SharkA small shark that takes
circular bites out of its prey. Also known as the
luminous or cigar shark.
Dogfish Shark Small, very common,
relatively harmless sharks found worldwide.
Galapagos Shark A large predator found near islands in warm
water.
Goblin Shark A bottom-dweller with a
long, flattened snout.
Great Hammerhead
Shark Large predators with a hammer-shaped head.
Great White Shark
An enormous, ferocious predator found worldwide.
Great White Shark
Simple VersionEnormous, ferocious
predators found worldwide.
Greenland Shark A large, slow-swimming
shark with glow-in-the-dark eyes.
Lemon Shark Large, yellowish
predators found near the surface and at
intermediate depths.
Luminous Shark A small shark that takes circular bites out of its
prey. Also known as the kiecutter or cigar sharcoo k.
Mako Shark
Large predators that are the fastest fish!.
Megalodon A huge, extinct
shark.
Megamouth A large, filter-feeding shark that
was only discovered in 1976.
Nurse Shark Large bottom-dwellers
with rounded fins.
Orthacanthus A spined, extinct
shark.
Port Jackson SharkA shark from waters off
southern Australia.
Sandtiger Shark (Sand Shark)
A shark that is cannibalistic before birth.
Shark Anatomy
Label the shark
Thresher Shark The Thresher Shark is a shark
Tiger Shark Large predators
found worldwide in
e xternal anatomydiagram. Answers
whose tail fin has a greatly elongated upper lobe.
warm seas.
Whale Shark
Zebra Bullhead Shark The largest f er that eats ish and a filter feed
tiny marine organisms and small fish. A bottom-dwelling shark with
zebra-like stripes.
Rays:
Manta Ray The largest ray.
Ray Flattened fish tha ed from sharks. t evolv
(meaning "Giant Tooth")
MEGALODON
Go to a Megalodon Printout
egalodon was an ancient shark that may have been 40 feet (12 m) long or Meven more. (There are a few scientists who estimate that it could have been up to 50 or 100 feet (15.5 or 31 m) long!) This is at least two or three times as long as the Great White Shark, but this is only an estimate made from many fossilized teeth and a few fossilized vertebrae that have been found.These giant teeth are the size of a person's hand! No other parts of this
ancient shark have been found, so we can only guess what it looked like. Since Megalodon's teeth are very similar to the teeth of the GreaWhite Shark (but bigger and thicker), it is thought that Megalodon mayhave looked like a huge, streamlined version of the Great White Shark.
t
MEGALODON'S DIET consisted mostly of whalesMegalodon's diet probably . Sharks eat about 2
s
EETH AND JAWS ely rare because sharks have no bones, only
y hard.
percent of their body weight each day; this a bit less than a human being eats. Since most sharks are cold-blooded, they don't have to eat as much awe eat (a lot of our food intake is used to keep our bodies warm). TShark fossils are extremcartilage, which does not fossilize well. Their teeth, however, are verTheir teeth are made of a bone-like material coated with hard enamel and they fossilize very well. Megalodon teeth are similar to those of the Great White Shark, but are much bigger, thicker, and with finer serrrations. Megalodon's jaws could open 6 feet (1.8 m) wide and 7 feet (2.1 m) hiThe jaws were loosely attached by ligaments and muscles to the skull, opening extremely wide in order to swallow enormous objects. It couldeasily swallow a large
gh.
Great White Shark whole!
Like most sharks, Megalodon's teeth were probably located in rows which
re
HEN MEGALODON LIVED o 1.6 million years ago, during the
s
EGALODON ANATOMY
rotated into use as they were needed. Most sharks have about 3-5 rows of teeth at any time. The front set does most of the work. The first two rows aused for obtaining prey, the other rows rotate into place as they are needed. As teeth are lost, broken, or worn down, they are replaced by new teeth. Megalodon may have had hundreds of teeth at one time. It did not chew their food like we do, but gulped it down whole in very large chunks. WMegalodon lived from roughly 25 tMiocene and Pliocene epochs. It is now extinct, but the exact time of itextinction is hotly debated. M
MEGALODON FOSSILS Fossilized Megalodon teeth up to 6.5 inches (17 cm) long have been found in Europe, India, Oceania (the general area around Australia including New Zealand, New Caledonia, etc.), North America, and South America. MEGALODON CLASSIFICATION Carcharodon megalodon was named by Agassiz in 1843. There is some debate as to whether megalodon was an ancestor of the Great White Shark or was an evolutionary dead end.
Kingdom Animalia (animals) Phylum Chordata Subphylum Vertebrata (vertebrates) Class Chondrichthyes (cartilaginous fish) Subclass Elasmobranchii (sharks and rays) Order Lamniformes Family Lamnidae (genus Carcharodon) or Otodontidae (genus Carcharocles) Genus Carcharodon (meaning "rough tooth") or Carcharocles (There is currently some debate as to whether the megalodon's genus should be Carcharocles or Carcharodon. Megalodon was once thought to be a direct ancestor of the white shark, Carcharodon carcharias, and so was put in the same genus; new evidence indicates that it not ancestral to the great white shark, so Megalodon was assigned to a new genus, Carcharocles) Species megalodon
PACIFIC ANGELSHARKSquatina californica
GENERAL DESCRIPTION The Angelsharks are flat-bodied sharks, very ray-like. They bury themselves in the sand or mud with only the eyes and part of the top of the body exposed. They have a blunt snout and are camouflaged to blend into the sand and rocks of the ocean bed. They have long, wide fins that look like wings, giving it its name. It is also known as the monk shark, sand devil, and monkfish. Angelsharks are frequently caught for food. TEETH Angelsharks have small, sharp teeth in trap-like jaws. SIZE The various species of Angelsharks range in size up to 6.5 feet (2 m) long. The Pacific Angelshark is up to 5 feet (1.5 m) long. DIET AND FEEDING HABITS Angelsharks eat fish, crustaceans, and mollusks. They spend the day hidden in the sand and rocks of the ocean bed. As fish swim by, the angelshark bursts up and surprises the prey, catching it in its trap-like jaws. HABITAT Angelsharks are bottom dwellers that live on ocean floors of depths from 10 to 4,300 feet (3 to 1300 m). They live in warm temperate oceans in the southern hemisphere. DISTRIBUTION Pacific angelsharks are found in the eastern Pacific Ocean , from southern Alaska, USA to Baja, CA, USA and from Ecuador to southern Chile. REPRODUCTION Angelsharks reproduce via aplacental viviparity with litters of 8-13 live-born pups. In aplacental viviparity, the eggs hatch and the babies develop inside the female's body but there is no placenta to nourish the pups. SPEED
Angelsharks are not extremely fast swimmers. Their prey is even slower. ANGELSHARK CLASSIFICATION Kingdom Animalia (animals) Phylum Chordata Subphylum Vertebrata (vertebrates) Class Chondrichthyes (cartilaginous fish) Subclass Elasmobranchii (sharks and rays) Family Squatinidae Order Squatiniformes Genus Squatina Species
aculeata africana argentina australis californica dimeril formosa japonica nebulosa oculata squatina tergocellata tergocellatiodes
GREAT WHITE SHARK
Carcharodon carcharias
GENERAL DESCRIPTION The great white shark is a streamlined swimmer and a ferocious predator with 3,000 teeth at any one time. This much-feared fish has a torpedo-shaped body, a pointed snout, a crescent-shaped tail, 5 gill slits, no fin
spines, an anal fin, and 3 main fins: the dorsal fin (on its back) and 2 pectoral fins (on its sides). When the shark is near the surface, the dorsal fin and part of the tail are visible above the water.
COLORATION Only the underbelly of the great white shark is actually white; its top surface is gray to blue gray. This is useful in hunting its prey. The great white usually strikes from below and its grayish top coloration blends in with the dark water, enabling it to approach the prey unobserved.
SIZE Great whites average 12-16 feet long (3.7-4.9 m)
long. The biggest great white shark on record was 23 feet (7 m) long, weighing about 7,000 pounds (3200 kg). Females are larger than males, as with most sharks. Shark pups can be over 5 feet (1.5 m) long at birth.
DIET AND FEEDING HABITS Young great white sharks eat fish, rays, and other sharks. Adults eat larger prey, including pinnipeds (sea lions and seals), small toothed whales (like belugas), otters, and sea turtles. They also eat carrion (dead animals that they have found floating dead in the water). Great whites do not chew their food. Their teeth rip prey into mouth-sized pieces which are swallowed whole. A big meal can satisfy a great white for up to 2 months. TEETH The great white shark has 3,000 teeth at any one time. They are triangular, serrated (saw-edged), razor-sharp, and up to 3 inches (7.5 cm) long. The teeth are located in rows which rotate into use as needed. The first two rows are used in obtaining prey, the other rows rotate into place as they are needed. As teeth are lost, broken, or worn down, they are replaced by new teeth that rotate into place. SENSES Shark's primarily use their sense of smell followed by their sensing of electric charges. The shark's other senses, like sensing changes in water pressure, eyesight, and hearing, are less important. The great white's nostrils can smell one drop of blood in 25 gallons (100 liters) of water. (Shark nostrils are only used for smell and not for breathing, like our nostrils. They breathe using gills, not nostrils.) The sensing of minute electrical discharges in the water is accomplished by a series of jelly-filled canals in the head called the ampullae of Lorenzini. This allows the shark to sense the tiny electrical fields generated by all animals, for example, from muscle contractions. It may also serve to detect
magnetic fields which some sharks may use in navigation. The great white is the only type of shark that will go to the surface and poke its head up out of the water. No one knows exactly why it does this; perhaps it is to see potential prey such as surface-dwelling sea lions. GREAT WHITE SHARK ATTACKS Most great white attacks are not fatal. Great whites account for about 1/2 to 1/3 of all 100 annual reported shark attacks. Of these 30-50 great white attacks, only 10-15 people die. SOCIAL GROUPS Great whites are usually solitary animals but are occasionally spotted travelling in pairs. HABITAT Great white sharks are found near shore along most of the temperate (not very hot and not very cold) coastlines around the world. DISTRIBUTION Great white sharks have been observed along the coastlines of California to Alaska, the east coast of the USA and most of the Gulf coast, Hawaii, most of South America, South Africa, Australia (except the north coast), New Zealand, the Mediterranean Sea, West Africa to Scandinavia, Japan, and the eastern coastline of China and southern Russia.
MIGRATION In the fall, some females migrate to warmer waters (for example, southern California) to give birth. SWIMMING Great whites are propelled through the water by their powerful tails. The fins are only used for balance. Their movement is more like an aircraft's
flight than other fishes swimming. They average about 2 mph (3.2 kph) but can swim 15 miles per hour (24 kph) in short bursts. They swim constantly or they will sink since, like other sharks, they have no gas filled swim bladder to keep them afloat like bony fish do. Like other sharks, their large, oily liver provides some buoyancy (floating ability). but they are still heavier than water and will sink unless they are propelling themselves through the water. Also like other sharks, they cannot swim backwards or even come to an abrupt stop, because their fins are not flexible like other fish. In order to go backwards, they must stop swimming and fall backwards, using gravity to propel themselves backwards.
It has been recently discovered that great white sharks can jump out of the water. They jump into the air from deep water in order to catch fast-swimming seals REPRODUCTION Great white sharks reproduce via aplacental viviparity; they give birth to 2-14 fully-formed pups that are up to 5 feet (1.5 m) long. Like all sharks, fertilization of the eggs occurs within the female. The eggs hatch within the female and are nourished by eating unfertilized eggs and smaller siblings in the womb. There is no placenta to nourish the babies - they must fend for themselves, even before birth. They swim away from the mother immediately after birth, there is no maternal care-giving. LIFE SPAN No one knows the life span of the great white shark. Some people estimate it to be about 100 years, but this has not been proven. POPULATION COUNT Great whites are decreasing in numbers and are rare due to years of being hunted by man. They are a protected species along the coasts of California, USA, Australia, and South Africa. GREAT WHITE SHARK CLASSIFICATION
Kingdom Animalia (animals) Phylum Chordata SubPhylum Vertebrata (vertebrates) Class Chondrichthyes (cartilaginous fish) Subclass Elasmobranchii (sharks and rays) Order Lamniformes Family Lamnidae Genus Carcharodon Species C. carcharias
GREAT WHITE SHARK ACTIVITIES A coloring/information print-out about the great white shark.
A simple coloring print-out about the great white shark.
A first grade shark addition activity. Solve the 1-digit addition problems, then do letter substitutions to answer a shark question.
GREAT WHITE SHARK LINKS A page about the great white shark at UCMP Berkeley. GREAT WHITE SHARK BOOKS The Great White Shark by Richard Ellis & John McCosker, 1991, Harper Collins, New York. Cousteau's Great White Shark by Jean-Michel Cousteau, 1992, H. N. Abrams, New York
GREAT HAMMERHEAD
SHARK Sphyrna mokarran
GENERAL DESCRIPTION The great hammerhead shark has a wide, thick head with the eyes at the margins. The head is indented at the center of the "hammer," which is almost rectangular in shape. This shark is gray-brown above with an off-white belly. The first dorsal fin (the large fin on the top of the shark that most people associate with sharks) is very large and pointed.
TEETH Teeth are triangular with extremely serrated edges.
SIZE The average great hammerhead shark is up to 11.5 feet (3.5 m) long. The largest reported was 20 feet (6 m) long. These large sharks average about over 500 pounds (230 kg) but can weigh as much as 1,000 pounds (450 kg). There are 9 species of hammerhead sharks, ranging in size from about 3 feet (0.9 m) long to over 20 feet (6 m).
DIET AND FEEDING HABITS The great hammerhead is a fierce predator with a good sense of smell that helps it find its prey. The great hammerhead eats fish, including rays, and other sharks, squid, octopuses, and crustaceans. The great hammerhead has been known to be cannibalistic.
Stingrays seem to be a particular favorite of the great hammerhead. It kills the ray by using its "hammer" to pin the stingray down while it takes bites from the ray's wings. HAMMERHEAD SHARK ATTACKS Many of the hammerheads are harmless to people, but a few species, like the great hammerhead, can be very dangerous.
HABITAT The great hammerhead swims in warm and relatively warm water along the coastlines. They live over the continental shelves and the adjacent drop-off (the upper part of the mesopelagic zone) to depths of about 260 feet (80 m). DISTRIBUTION The great hammerhead is found in tropical and sub-tropical waters worldwide.
MIGRATION The great hammerhead migrates seasonally to cooler waters during the summer.
REPRODUCTION The great hammerheads are viviparous, giving birth to live young. The 20-40 pups are about 27 inches (70 cm) long at birth.
HAMMERHEAD SHARK CLASSIFICATION
Kingdom Animalia (animals) Phylum Chordata
SubPhylum Vertebrata (vertebrates) Class Chondrichthyes (cartilaginous fish) Subclass Elasmobranchii (sharks and rays) Order Carcharhiniformes Family Sphyrnidae
Genus Eusphyra o Species blochii: the winghead shark
Genus Sphyrna o Species corona: Scalloped bonnethead o Species couardi: Whitefin hammerhead o Species lewini: Scalloped hammerhead, bronze hammerhead, kidney-
headed shark o Species media: Scoophead o Species mokarran: Great hammerhead o Species tiburo: Bonnethead, shovelhead, bonnet shark o Species tudes: Smalleye hammerhead o Species zygaena: Smooth hammerhead, balance fish, black
hammerhead