ESS 100 Dinosaurs Midterm

mesozoic

252 mya to 66 mya, dinosaurs only showed up ~230 mya

dinosaur

mesozoic, terrestrial reptile that walked with an upright stance

Argentinosaurus

largest dinosaur

Microraptor

one of the smallest dinosaurs, modern day China

Scipionyx

one of the smallest dinosaurs, modern day Italy

Megalosaurus

1st dinosaur described in scientific literature by William Buckland

Hadrosaurus

duck-billed, 1st dinosaur described from North America

Reptile characteristics

Tetrapod vertebrate, scaly skin, short legs relative to body size, relatively small brain, 3-chambered heart, cold-blooded, amniotic eggs

anapsida

fossil reptiles, no postorbital fenestra, ex. pariesaurus

diapsida

all other reptiles (living and extinct), 2 postorbital fenestra, includes all dinosaurs, pterosaurs, marine mammals, snakes, crocs etc.

synapsida

mammal-like reptiles, 1 postorbital fenestra

archosaur characteristics

antorbital fenestra, mandibular fenestra, high narrow skull, pointed snout, teeth set in sockets, fourth trochanter on femur

pterosaurs

flying reptiles, most closely related to dinosaurs, skin stretched across arm and extended 4th finger

dinosauria characteristics

upright stance, at least 3 fused sacral vertebrae, pelvic girdle with acetabulum, femur with angled ball joint, expanded ilium/pelvic girdle to attach to the sacrum, ribs with two heads, complex forward-facing shoulder girdle

saurischia

lizard hipped, pubis pointed forward with a "boot" on the end, herbivores and carnivores

ornithischia

bird hipped, end of pubis bone pointing backwards, all herbivores, leaf shaped teeth, have spine-strengthening ossified tendons along the backbone

Triassic characteristics

generally small body, bipedal stance, long hind legs and fore limbs, long necks, small head, sharp teeth

Eoraptor

1 m long, 10 kg, large orbits, pointy teeth and elongated snout, possible common ancestor with Eodromaeus

Mbiresaurus raathi

2 m long, 30 kg, leaf-shaped teeth, phylogenetically different from Eoraptor

Eodromaeus

most primitive features of known dinosaurs, skull with large fenestra, pointed teeth, characteristics indicate common ancestor with Eoraptor

Herrerasaurus

light build, 3-6 m long, 250-300 kg, 1 m hip height

Coelophysis

earliest North American dinosaur, late Triassic, 2-3 m long, 20 kg, slender long hollow limb bones, skull with many fenestra

Plateosaurus

largest late Triassic dinosaur, 8 m long, leaf-shaped teeth, long neck, sturdy forelimbs

Nyasasaurus parringtoni

240 mya, bony crest on upper arm (deltopectoral crest), cannot be confirmed as a dinosaur

Asilisaurus kongwe

dinosauriform, 243 mya, potential omnivore

Basal Ornithischians

considered ancestral to all other ornithiscians, small, lightly built, mostly early Jurassic

Lesothosaurus

90 cm tall, probably bipedal, slightly derived because of their inset tooth row (cannot see teeth on the outside, cheeks cover them), BO

Heterodontosaurus

has multiple different types of teeth, small, slender limbs, long tail, large hands, facultative quadrupedal, BO

Leaellynasaura

1.5 m long, 10 kg, South Australia, large orbits and enlarged optic nerve, theory that better eyesight meant they were active during dark winters in the southern hemisphere, early Cretaceous, BO

Thyreophorans

armored lizards, bony armor, obligate quadrupedal, small heads, antorbital fenestra are mostly closed, leaf shaped teeth, ornithischians

Stegosaurus

1 type of thyreophoran, 9 m long, 3000 kg, evidence of hooves on feet, 17 bony plates on back (most likely for species recognition or sexual selection), no evidence ankylosaurus descended from stegosaurus

Ankylosauridae

1 type of thyreophoran, only Cretaceous (which it replaced stegosaurus during), whole back has bony plates embedded in skin, 25 genera of ankylosaurus, no evidence ankylosaurus descended from stegosaurus