BIO 200 Lecture Notes - Lecture 33: Mountain States, Haversian Canal, Poikilotherm
3 Jun 2019
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Document Summary
Dinosaurs are reptiles that originated 230 mya and dominated the earth until 66. Mya when a massive extinction occurred when an asteroid hit earth causing global devastation. The only survivors of the dinosaur line were birds. Dinosaurs had a huge size range and lived in a variety of habitats, from tropics to the arctic, aquatic and land. Fossil dinosaurs occur on every continent and over 1000 species have been named. Fossils are most plentiful throughout the rocky mountain states into canada which during the dinosaur era was a swampy tropical habitat at the edge of an inland sea. The evidence based on their size, posture, locomotion, predator/prey ratios, growth rings and haversian canal numbers suggests they were at least mesotherms if not homeotherms. Flight has independently evolved many times in insects, bats, pterosaurs, and birds and a host of gliding species like flying fish, squirrels, frogs, etc.
