BIOL108 Lecture 34: Dec.2 (Mammalia)

• School: University of Alberta
• Department: Biology (Biological Sciences)
• Course: BIOL108
• Professor: Lien Luong

Document Summary

Amniote phylogeny, two major classes: reptilian and synapsida. Synapsids have one hole in the skull instead of two. The anapsids have no holes, and the diapsids have 2 holes. Therapsids: characterized by the enlargement of the dentary bone in the jaw. In mammals, the jaw consists only of this bone. Development f a bony secondary plate: a partition to separate the nasal passages from the oral cavity. Allows chewing and breathing at the same time. Mammalian characteristics: mammary glands: glands that secrete nutritious fluid (milk) to feed offspring. The origin of mammary glands are not clear. The bones from the leftover jaw pieces moved from the reptiles to the mammals, and became the inner ear. There was a movement of leftover jaw bones to the middle ear. Reptile ears have only 1 bone and mammal ears have 3 bones. The eardrum moves from close to outside in reptiles to quite deep in the head of the mammals.