Dinosaurs

I.G. Kenyon

How Many Dinosaur Species? More than 500 Genera

Approximately 1,000 species

Herbivorous V Carnivorous

Dromaeosarus albertensis

Study of dinosaur morphology-mode of life may be established

Uniformitarianism – study of modes of life of modern herbivores and carnivores and predator-prey relationships help to infer the

niches that dinosaurs occupied in the Mesozoic ecosystems

Bipedal – fast/agile runnersLong balanced tail for turning at speed

Large brain body mass ratioLarge forward facing eyes

Endothermic-covered in feathersStrong jaws with sharp teeth

Sharp claws on forelimbs/feet for slashing preyMay have hunted in pairs or packs

Evidence for Carniverous

Carnivorous Dinosaurs

Flexible base to tail

Large forward facing eyes Bipedal , fast, agile

walked/ran on tiptoe

Carnivorous Dinosaurs

Tail carried upright aids manoeuvrability and

change of direction when running at high speed

Strong skull with powerful jaws and sharp teeth

Sharp claws on fore limbs for

slashing prey

Carnivorous DinosaursCovered in feathers to keep warm

and maintain a high metabolic rate? Probably warm blooded

Sharp claw on second toe of foot used for

slashing at preyMay have hunted in pairs or packs

Spinosaurus – The Largest Carnivore?

12.6 to 18 metres in length

Weighed 7.0 to 20.9 tonnes

Cretaceous 97-112 Ma

Lived on land and in water like a modern crocodile

Mainly a fish eater and had vertebrae extensions covered

with skin to form a sail-like structure on its back

Large body massQuadrupeds/4 legged

Spikes, nobbly bits, horns for defenceHorny beaks with small/no front teeth

Neck lengths varied according to type of grazerGastroliths found inside the stomachs

Lived in large herds/Juveniles shielded on the insideSmall brain to body mass ratio

Evidence for Herbiverous

Evidence for Herbiverous - StegasaurusShort neck and small head

probably grazed bushes close to the ground

Grazed in herds much like elephants do today

on the plains of Africa

Walnut sized brain!

Four legged, bulky and heavy about the size of a double decker bus

Heavily armoured, plates on back may have been thermo-regulatory

Evidence for Herbiverous - Stegasaurus

Toothless beak and small cheek teeth

Sharp tail spikes to swing for protection

Late Jurassic 150 to

155 Ma

Gastroliths (Stomach Stones)

Psittacosaurus fossil with gastroliths in its stomach region, American Museum of Natural History

Psittacosaurus

Many herbivores swallowed stones (gastroliths) to help break down tough, fibrous plant

material in their stomachs

Over time the stones became very smooth and polished

Yummy! Rock Cakes on the menu again!

Herbivorous Dinosaurs

Argentinosaurus – The Largest?

Argentinosaurus – The Largest?

Incomplete Argentinosaurus femur shaft measuring 1.18 metres long

From this it is estimated that the animal must have been

between 30 and 35 metres in length

The animal is thought to have weighed 80 to 100 tonnes

Late Cenomanian (Cretaceous)

94 – 96 million years old

Argentinosaurus – The Largest?Kingdom Animalia

Phylum ChordataClass ReptiliaNode DinosauriaOrder SaurischiaSub-Order SauropodomorphaBranch TitanosauriaFamily AntarctosauridaeGenus ArgentinosaurusSpecies huinculensis

Skeletal reconstruction in the Senckenberg Museum, Germany

Relative Sizes – Dinosaurs, Elephants, Man

Herbivorous dinosaurs – the largest creatures ever?

Not quite, the Blue Whale today is the largest creature ever to live

weighing 180 tonnes and 30m long

Humans 7.4 – 7.8Bottlenose Dolphin 4.14Chimpanzee 2.2 – 2.5Dog 1.2Cat 1.0Sheep 0.8Rabbit 0.4

A more complex version of the brain to body mass

ratio

That’s All

Folks!