Dinosaurs Flashcards
Marine Reptiles
(Plesiosaurs, Ichthyosaurs) first appear in Triassic Period
Reptiles also took to the sea during the Mesozoic Era
What does an Ichthyosaur look like?
Gave birth to live young due to their aquatic lifestyle
They looked like dolphins with vertical tail flukes (this demonstrates evolutionary convergence)
Dinosaurs of the Jurassic Period
giant sauropods
And some large carnivores
What do fossil trackways tell us about dinosaur social structure?
It suggests herd-like behavior among sauropods
Dinosaurs of the Jurassic Period
Allosaurus
A big carnivorous dinosaur. The main predator during the Jurassic
Two major divisions of dinosaurs based on pubis bone
ornithischia (“bird hipped”)
saurischia (“lizard hipped”)
ornithischia
pubic bone rotated backwards
Saurischia
pointing forward
Ironically, birds evolved from saurischia, despite the fact that birds have pubis bones that point backwards
Solnhofen Limestone (Jurassic): Archaeopteryx
half bird, half dinosaur
What morphological features of Archaeopteryx are more bird-like?
Bird-like features: feathers, long forelimbs, crescent-shaped wrists. The wishbone is the same structure that birds have
What morphological features of Archaeopteryx are more dinosaur-like?
Dinosaur features: still had teeth and a long tail
What is significance of furcula (wishbone)? (Archaeopteryx)
Intermediate pubis bone
Cretaceous dinosaurs:
Tyrannosaurus rex, Velociraptors, Hadrosaurs (duck-billed dinosaurs), Ceratopsians (horned dinos)
Cretaceous: Quetzalcoatlus
largest animal to take flight (giant pterosaur)
Cretaceous: Mosasaurs
(large, carnivorous marine reptiles)
Main predator of the Cretaceous seas
