Flashcards in Dinosaurs Deck (20):
What is a dinosaur?
Mesozoic reptile with upright position or walking gait
How are dinosaurs classified?
Relies entirely on shape of bones, coprolites, trackways, gastroliths and feathers
What are the two main classes of dinosaur?
Ornithischia- two bones in the hip point backwards, bird hipped
Saurischia- one of the bones in the hip points forward, reptile hipped
What are amniotic eggs?
Types of eggs produced by birds and reptiles with shells. Shells allowed for life on land without water source for reproduction, eggs provided aquatic environment, no need for larval stage, infant develop into miniature version of the adult
When did dinosaurs begin to evolve?
Evolved after the Permo-Triassic extinction, 251Ma, evolved into two separate classes, evolved from archosaurs in Triassic, Therapods prolific in Triassic, larger Sauropods in Jurassic, number of Ornithischian increased in Cretaceous
What are the main characteristics of saurischian dinosaurs?
Primitive arrangement of hip bones, pubis bone points forwards
Long s shaped necks,
Hands consisted of only three digits
What characteristics are displayed by Ornithiscian dinosaurs?
Hips arranged similar to birds, both point backwards
Front teeth are small or absent , replaced by beak
Armoured with bony plates, for defence and heat exchange
What class of dinosaur is diplodocus?
What characteristics are displayed by diplodocus?
Long thin neck, could reach vegetation in forests most others couldn't,
peg like teeth at front of jaw couldn't chew
Gastroliths, to aid digestion of leaves
Long but lightly built body
Extra bones underneath the spine for support and mobility
Tail long and whiplike, could have been used for defence
What class of dinosaur is Tyrannosaurus
When was diplodocus common?
Jurassic and Cretaceous
What are the characteristics of Tyrannosaurus?
Largest terrestrial predator, Carnivore
Predator or scavenger debate, scavenger because of small eyes, heavy frame and big legs, large olfactory lobes and tiny forelimbs
Predator because not many animals willing scavenge, could be successful without forelimbs, large, curved teeth
When was T. rex common?
What class of dinosaur is Iguanodon?
What are the main characteristics of iguanodon?
Large and heavily built, horselike about with horns toothless beak. Cheek teeth, could chew due to hinged upper jaw,
Three digit hands ending in hooves, conical thumb spike
Could be quadrupedal or bipedal
How did birds evolve?
Most accepted theory is that birds evolved from Therapoda dinosaurs in the Jurassic, as similar to coelurosaurs
What skeletal similarities can be seen between coelurosaurs and archaeopteryx?
Hollow, thin walled bones
S shaped curved neck
Elongated arms and forelimbs and clawed hands
Pubis shifted from anterior to posterior
What is archaeopteryx?
First known bird like fossil, intermediate between birds and reptiles, semi arboreal, lived in trees, capable of gliding and potentially sustaining flight.
What dinosaur like features where prominent in archaeopteryx
Long bony tail
There's digit on each wing with claws
About with reptilian teeth
Sternum not bony or keeled
Gastralia, belly ribs present
A shaped curved neck