WFSC 302 Study Guide - Midterm Guide: Digastric Muscle, Hominidae, Hypsodont
10 May 2016
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Document Summary
Mammals and mammal-like reptiles diapsids two fenestrae behind orbit lepidosaurs (tuataras, lizards, snakes) and archosaurs (crocodiles, dinosaursaurs, and birds) Nonmammalian synapsids none of these are monophyletic: pelycosaurs (pelycosauria) Increased metabolic rate, heading toward direction of endothermy: cynodont therapsids (cynodontia, closely related to the living organisms. Synapsids were the first amniotes to radiate in terrestrial habitats: paleozoic- late carboniferous (300 mya, permian- synapsids were the most abundant terrestrial vertebrates, triassic- top carnivores, pelycosaurs- not monophyletic. Includes sailbacks such as dimetrodon for thermoregulation, ectothermic: notable characteristics. Complexity in dentition- movement away from homodont. Arched palate: oral cavity normally collapses into nasal cavity (reptiles, evidence of beginning bone development. Lower jaw flange for muscle attachment stronger jaw: ancestral condition is swallowing prey items whole, new development allows for tearing up prey, not dinosaurs! Increased neck flexibility: cynodont therapsids- mammalian ancestors, more modifications for increased metabolic rate- leading toward endothermy. Enlarged infraorbital foramen- where sensory nerves from whiskers attach.
