LSC 294 — Dinosaurs

Udo Savalli Home

Lab 10
Herbivorous Dinosaurs

Thyreophora

Basal Thyreophorans Most primitive of the Thyreophorans Armor plates are small and do not connect or form spikes Hind limbs longer than forelimbs: probably partially bipedal

Stegosauria 2 rows of enlarged dorsal osteoderms that form vertical plates or spikes 4 spikes at end of tail ("thagomizer") Head very small Forelegs shorter than hindlegs	Hesperosaurus skeleton, Late Jurassic, North America (MAL1)

Ankylosauria Osteoderms form a nearly contiguous dorsal shell-like covering Body very wide and low to the ground Many have laterally-projecting spikes	Gastonia skeleton, Early Cretaceous, North America (MAL)

Marginocephalia

Pachycephalosauria Dome-headed (or bone-headed) dinosaurs Top of skull is greatly thickened (may be flat or dome-shaped) Skull usually has various knobs or spikes Bipedal Snout ends in broad beak	Pachycephalosaurus skeleton, Late Cretaceous, North America (MAL)

Ceratopsia Horned dinosaurs (though not all have horns) Narrow snout with parrot-like beak Projecting bones at side of skull near cheek Most have enlarged bone frill extending from back of skull Many have varied arrangements of horns or spikes on skull Dental batteries indicate efficient chewing Quadrupedal (except primitive Psittacosaurus)	Albertaceratops skeleton, Late Cretaceous, Montana (WDC2)

Ornithopoda

Hypsilophodontidae Most primitive group of Ornithopods Relatively small size Bipedal; probably fast runners	Thescelosaurus skeleton, Late Cretaceous, North America (MAL)

Iguanodontia Paraphyletic grouping of species intermediate between Hypsilophodonts and Hadrosaurids Moderate to large size Moved both bipedally and quadrupedally Necks relatively long Generally lacked any head ornamentation Some had enlarged thumb spikes	Probactrosaurus adult & juvenile skeletons, Early Cretaceous, China (AMNH3)

Hadrosauridae "Duck-billed Dinosaurs" Large size Mostly quadrupedal (but may have run on hind legs) Mouth generally broad and flat Had well-developed dental batteries for efficient chewing Many with distinctive head crests Uncrested forms may have had inflatable nasal sacs	Edmontosaurus skeletons, Late Cretaceous, North America (MAL)

Herrerasauridae

Primitive group of Saurischian Dinosaurs Bipedal runner: long hind legs, short forelegs Relatively small size Squarish skull Superficially resemble Theropod dinosaurs Carnivorous Evolutionary relationships are uncertain (may be primitive members of Theropoda)

Herrerasaurus skeleton, Middle Triassic, Argentina (MAL)

Sauropodomorpha

Prosauropoda Long necks, small heads Bipedal: forelegs smaller than hindlegs	Plateosaurus skull, Late Triassic, Europe (MAL)

Sauropoda Necks long to extremely long Heads proportionately tiny Quadrupedal Tails often very long Large to enormous sized	Argentinosaurus skeleton, Late Cretaceous, Argentina (FMNH4)