Dinosaurs What shared novelties unite the dinosaurs? Dinosaur means "Terrible lizards" Dinosaurs were mostly large, bipedal or quadrupedal diapsid reptiles with an upright posture. Most of the traits that characterize dinosaurs are related to their upright posture and locomotion.
Dinosaur Hip Bones
Ornithischia:The bone on the bottom of the pelvis has a large projection that points toward the back of the animal.
Saurischia:The bone on the bottom of the pelvis has a large process pointing toward the front of the animal.
Scientists divide dinosaurs into two groups--ornithischians and saurischians--according to the structure of the hips. Ornithischians, such as Corythosaurus, had a birdlike hip structure. Saurischians, such as Allosaurus, had hips like those of lizards. The two groups differed in the three bones that made up the hipbone--the ilium, ischium, and pubis.
Pisanosauruswas a small (>1 m), bipedal dinosaur with serrated, shearing teeth.
Jurassic-Cretaceous: quadrupedal herbivores, largest land animals, up to 35 m long, 12 m tall, 80,000 kg (or more), small heads, broad snout with peg-like teeth (and gastroliths in gut), very long necks and tails, massive pillar-like limbs, short broad hands and feet with claws, large lightweight vertebrae.
The Sauropoda were large herbivores such as Apatosaurus and Diplodocus
Bird-like, bipedal carnivores. The hand has three or four fingers withclaws. They had a long bony tail. They reduced their toes until just 3 touch the ground.
The Theropoda were bipedal carnivores (meat eaters), ranging from the chicken-sized Compsognathus and the fearsome Deinonychus and……….
The most unusual feature of this theropod is the pair of ridges along the top of the skull
Dilophosaurus did not have a neck frill (it had standard neck ribs) nor did it spit venom (it lacks hollow fangs through which snakes expel venom).
A group of large carnivorous dinosaurs that roamed North America and Asia during the last part of the Cretaceous, 85 to 65 million years ago.
The most famous tyrannosaur, of course, is Tyrannosaurus rex, one of the last non-avian dinosaurs to walk the earth before the great extinction.
It stood approximately 15 feet high and was about 40 feet in length, roughly six tons in weight.
In its large mouth were six-inch long, sharp, serrated teeth.
Ankylosaurs: "Fused lizards":
Jur-Cret: 5 to 9 m long. Quadrupedal with heavy flexible armor of fused plates, studs, and spikes. Broad shielded skull, short massive limbs, sturdy tail with club.
Ceratopsians: "Horned faces":
Cret: bipedal and quadrupedal, small to large (1 to 9 m long), triangular skull often with bony frill, tall narrow snout with parrot-like beak, battery of shearing teeth, horns. Evidence for herding.
Jur-Cret: bipedal, small to large (0.5 to
5 m long), thick domed or flattened heads (Head butting) with bumbs, strong hips and legs, short arms, stiffened tail, spine horizontal.
Tri-Cret: diverse and abundant herbivorous group, bipedal quadrupedal, small to very large (1 to 15 m long), legs longer than arms, fingers with claws or hooves (5th one reduced), toes with hoof-like nails (5th toe reduced), long stiff tail held off ground for balance, large head with cropping beak and battery of self- sharpening cheek teeth, cheek pouches.