PALEO200 Lecture Notes - Lecture 11: Mosasaur, Theropoda, Dicynodont

• School: University of Alberta
• Department: Paleontology
• Course: PALEO200
• Professor: Angelica Torices

Document Summary

Dimetrodon: looks prehistoric (toothy grin, sprawling gait, unusual sail) More closely related to humans than to any other dinosaur. Synapsid indicated by single opening behind the eye. Single hole/fenestrae behind the eye: amniotes: vertebrates that lay hard-shelled eggs. Can be subdivided into several groups based on number of holes/fenestrae in the skull. Anapsids: don"t have any extra skull openings behind the orbit. Dinosaurs had two openings in the skull behind each orbit diapsids. Archosauromorph: more holes in the skulls; fenestrae in front of the orbit called antorbital fenestra and hole in the lower jaw called the mandibular fenestra. Dinosaurs were archosauromorphs because of the antorbital and mandibular fenestrae. Includes modern day lizards, extinct marine lizards mosasaurs o. Final major division leading to dinosaurs has to do with differences mostly in the ankle bone. Non-dinosaur archosaurs like crocodiles have ankle joints in which it articulates with a peg and socket.