BIOL108 Lecture Notes - Lecture 23: Hylonomus, Anapsid, Lepidosauria

• School: University of Alberta
• Department: Biology (Biological Sciences)
• Course: BIOL108
• Professor: Heather Proctor

Document Summary

Extant members of the amniote clade include mammals and repiles: where repiles= lizards, snakes, turtles, crocodiles, tuataras, dinosaurs 9including birds), and some others. Most amniotes have eggshell impervious to water loss: calcareous or leathery, lost in most mammals. Copulaion & internal ferilizaion amnioic egg: eggshell laid down inside female reproducive tract ater egg is ferilized, but note that copulaion and internal ferilizaion not unique to terrestrial vertebrates. Waterproof skin: reduces water loss to atmosphere, therefore must rely solely on lungs for gas exchange (with excepions of a few turtles) Use muscles associated with rib cage to more eiciently venilate lungs: as opposed to using relaively ineicient buccal pump. Repilia, including birds: previously birds were excluded from the taxon repilia. Synapsida: includes mammals and numerous exinct taxa. Approach to repilia early taxonomists had good reasons for excluding birds (aves) from their concept of. Repilia have so many unusual, derived features that it is hard to provide generalizaions for.