Earth Sciences 2266F/G Lecture Notes - Lecture 23: Cranial Kinesis, Shoulder Girdle, Acrodont
28 Mar 2020
School
Department
Course
Professor
Document Summary
Inherited from basal diapsids, lead to development of flippers: sliding joint b/w coracoids and sternum. Coracoids slide along sternum behind interclavicle (allow longer stride: dentition (growth habit) Acrodont: each tooth reside in shallow socket on outer surface (weak attach) Pleurodont: teeth fuse to inner side of jaw (strong attach-semi permanent) Thecodont: fixed in deep sockets (replace w/in same socket) Basal forms: distinguish by quadrate, support tympanum, cleithrum (present in basal) is lost in pectoral girdle. Lepidosauria: overlapping keratinous scales, mid-dorsal scale row, paired male reproductive organs, ability to self-amputate tail, rhyncocephalians. Cranial kinesis: gekkota: toes pads to help them climb, no eyelids (lick to moist, lacertoidea/scincoidea (true lizards): slender w/long tails, amphisbaenians: no limbs, burrowing, pink, serpentes: no limbs, bone fused into cylindrical unit, kinesis. Hypothesis for snake night vision : aquatic hypothesis: visual systems modified for light underwater, loss of eardrum, fossorial hypothesis: didn"t need sight, lost of eardrum for picking up vibration w/jaw.
