BIOL 204 Study Guide - Eureptilia, Epiglottis, Temporal Bone
Document Summary
Spiracle (reduced gill opening) remains between hyoid and mandibular arches. Splanchnocranium partially or completely replaced by dermal bone. Synapsids: (allowed muscles to insert closer to teeth. ) Upper jaw merged with floor of braincase. Mammals, turtles (parareptilia), crocodiles and amphibians do not have kinetic skulls. Quadrate has loose articulation with cranium; allows jaw to swing forward and backwards. Results in a powerful bite (forces directed towards prey; more teeth) Snake = lost upper and lower temporal bar; mandible unfused in midline. Mammals = synapsid, complete secondary palate, epiglottis. Mandible articulates with to support gills instead. unsupported palatoquadrate. Jaw supported by both the hyomandibula and the chondrocranium. Upper jaw drops down in pendulum-like motion. Teeth only used to grasp and cut prey; weak bite. Use force of swimming (by rotating its body) and sharp teeth to increase force. Processes on upper jaw to prevent lateral strain. Lower jaw is depressed, pulls maxilla forward and allows lower jaw to drop.
