mesozoic era
DESCRIPTION
Mesozoic Era. Life. Mesozoic Life. Known as “Age of Reptiles”. Mammals and angiosperms evolve. Marine Invertebrates Plankton. 1 st appeared (Jur). Coccolithophores. Abundant (K). Continue today. Diatoms (SiO 2 ). 1 st evolved (K). Cold H 2 O. Dinoflagellates. Warm H 2 O. - PowerPoint PPT PresentationTRANSCRIPT
Marine InvertebratesPlankton
• Coccolithophores– 1st appeared (Jur)– Abundant (K)– Continue today
• Diatoms (SiO2)
• Dinoflagellates
– 1st evolved (K)– Cold H2O
– Warm H2O
• Foraminifera– Exploded
• Most plankton extinct (end K)
Marine InvertebratesCorals & Echinoderms
• Corals & Echinoderms proliferated
Scleractinians Echinoderm
MollusksBrachiopods & Gastropods
• Significant invertebrate fauna
– Minor invertebrate
– Never fully recovered from Permian extinction
• Brachiopods
• Gastropods
– Largest, most varied class
– Marine, fresh H2O, terrestrial
– Herbivore & carnivore
MollusksBivalves
– i.e., oysters, clams
– Rudists significant Formed large tropical reefs Excellent guide fossils
• Burrowing organism– Escaped predators
MollusksCephalopods
• Important invertebrate group• Ammonites
– Complex sutures
– Abundant (Jr & K), extinct (end K)
• Nautiloids and belemnoids survived
Nautilus
Cephalopod
Mesozoic LifeFishes and Amphibians
• Cartilaginous fish– ↑ abundance
• Amphibians– Frogs and salamanders appear
– Greatest diversity (Permian)
Mesozoic LifePlants
• Gymnosperms– Gingkos
• Primary producers – base of food chain
– Conifers– Cycads
• Gymnosperms replaced by angiospermsModern cycads
AngiospermGymnosperm
PlantsAngiosperms
• Adapted to nearly every terrestrial habitat• Factors to success:
– Method of reproduction Evolution of flowers
Evolution of enclosed seed
• Pollinators
• Seeds dispersed by wind, fruit, burr
Mesozoic LifeReptiles
• Thecodontian (L. Per-Tri)– Small, agile reptiles with
long tails, short limbs
– Dinosaur ancestors
– Teeth set in sockets
– Quadrupedal, ran bipedal– Herbivores & carnivores
• Diversification began during Penn
– Evolution of captorhinomorphs 1st to lay amniote egg All other reptiles evolved
i.e. crocs, dinos, & mammal-like reptiles
Warm-Blooded Dinosaurs• Ectotherm – “cold-blooded”
– Animals whose body temp varies in response to outside temp
• Endotherm – “warm-blooded”
– Capable of maintaining a constant body temp regardless of outside temp
• All reptiles ectothermic
• Dinosaurs believed to be endothermic
• Mammals & birds endothermic
• Endotherm requirements
– High metabolic rates need to eat more
– Complex nervous system large brain
Dinosaurs 3.5% prey pop’n Similar to present-day mammals
Many dinos have small brains Small carnivores = large brain
– Dino bones numerous passageways = blood flow
Crocs, turtles have similar bone structure = ectotherm
Warm-Blooded Dinosaurs
– Active flight requires endothermy Pterosaurs = hair-like feathers Triceratops brain cavity
Mesozoic LifeDinosaurs Relationships
• Two independent orders evolved1. Saurischia “lizard-hipped”
2. Ornithischia “bird-hipped”
– Theropod & Sauropod
DinosaursSaurischia Theropod
• Theropods – “Carnivores”– Bipedal locomotion
60 cm to 15 m 2 kg to 8 tons
– Tyrannosaurus (largest terrestrial carnivore)
– Deinonychus – “terrible claw”
– Various sizes
DinosaursSaurischia Sauropod
• Sauropods – “Herbivores”– Quadruped locomotion– Largest land animals to
ever exist
Camasaurus “Brontosaur”
Diplodocus Brachiosaurus
20 to 35 m in length 10 to 55 tons
Mesozoic LifeDinosaurs Relationships
• Two independent orders evolved
1. Saurischia
2. Ornithischia
– Theropod & Sauropod
5 groups
DinosaursOrnithischia
1. Duck-billed dinos (K)– Colonial nesting, cared for
young, herbivores, bipedal
2. Pachycephalosaurs – Dome-shaped skull,
bipedal, butting3. Ankylosaurs
– Armored, quadrupeds, tail w/ club-like growth
4. Stegosaurs– Quadruped, herbivore with
spike on tail5. Certopsian
– Triceratops, quadrupedal herbivores
Mesozoic LifeWinged Dinosaurs
• Pterosaurs
– 1st flying vertebrates
Winged membrane supported by elongated finger
– Flight adaptations
• Pteranodon (K)
– Pterosaur
– Could actively fly
Mesozoic LifeBirds
• Few Meso birds
– Archaeopteryx
Jur strata, Germany
– Protoavis (Tri)
Crow sized Hollow bones
Mesozoic LifeEarly Mammals
• 1st mammals (Tri)
– Evolved from Therapsids Mammal-like reptiles
– Small, rodent-like mammals
• Cynodonts
– Most abundant mammal-like reptile
• Monotremes
Early MammalsCynodonts
– Egg-laying– i.e. today’s platypus & string
anteater
• Eupantotheres– Marsupials – pouched (E. K)
– All living mammals related to this branch – Placental mammals
Mesozoic LifeFrom Reptile to Mammal
• Used skeletal structure to classify fossils
– Skull – Middle ear – Lower jaw – Teeth
– Mammal’s middle ear attached to dentary– Reptiles = 1 ear bone; mammals = 3– Reptile = several jaw bones; mammals = 1– Teeth = distinct types
Mesozoic Era Mass Extinction
• Impact Theory
– Huge asteroid or comet
– Cloud of dust into atmosphere
– Reduced sunlight
Plants die first Herbivores followed Then, carnivores starved
Mass ExtinctionEvidence
• Large impact basin
• Iridium-rich clay layers– Rare crustal rock– More in meterorites
• Clay layers, New Mexico