First EAS Flashcards

acetabulum

The hip socket hole in dinosaurs; allows femur to tuck under body for upright posture

antorbital fenestra

Skull opening in front of the eye; defines archosaurs (dinosaurs

Permian-Triassic extinction

The largest mass extinction (~252 million years ago); caused by Siberian Traps volcanism + coal burning; ended Paleozoic era

Cretaceous-Paleogene extinction

The K-Pg extinction (~66 million years ago); killed non-avian dinosaurs; caused by Chicxulub asteroid + Deccan Traps

amniotic eggs

Eggs with shell and membranes that allow reproduction on dry land; evolved in Carboniferous; defines reptiles

endothermic

Warm-blooded; generates internal heat; suggested for some dinosaurs (especially theropods) based on bone histology

ectothermic

Cold-blooded; body temperature depends on environment; traditional view of non-avian dinosaurs

convergent evolution

Unrelated groups evolve similar features independently; example: ichthyosaurs and dolphins

Pangea

The supercontinent from late Paleozoic to early Mesozoic; caused dry continental climates

Siberian Traps

Huge flood basalt province in Siberia; erupted at Permian-Triassic boundary; caused global warming

Deccan Traps

Huge flood basalt province in India; erupted around K-Pg boundary; stressed ecosystems before asteroid impact

theropods

Bipedal carnivorous dinosaurs; birds evolved from them; only carnivorous dinosaur group

sauropods

Long-necked herbivorous dinosaurs; dominant in Jurassic; used gastroliths for digestion

stegosaurs

Plated herbivorous dinosaurs; dominant in Jurassic; armored with bony plates

ornithopods

Duck-billed herbivorous dinosaurs (iguanodonts

ceratopsians

Horned herbivorous dinosaurs (e.g.

ankylosaurs

Heavily armored herbivorous dinosaurs with tail club; dominant in Cretaceous

pterosaurs

Flying archosaurs; not dinosaurs; wing membrane stretched across 4th finger to legs

ichthyosaurs

Marine reptile; convergent with dolphins; lived in Mesozoic seas

plesiosaurs

Marine reptile with long neck; lived in Mesozoic seas

furcula

The wishbone; formed from fused clavicles; found in theropods and birds

gastroliths

Stomach stones swallowed by some dinosaurs (especially sauropods) to grind plants

upright posture

Limbs positioned directly under the body; enabled by acetabulum; typical of dinosaurs

bipedal

Walking on two legs; early theropods and some ornithopods

Cambrian explosion

Rapid appearance of most animal phyla in early Cambrian (~541 million years ago); recorded in Burgess Shale

Snowball Earth

Severe glaciation ~0.7 billion years ago; glaciers reached tropics; followed by first animals (Ediacaran fauna)