BIOL 111 Lecture Notes - Lecture 20: Skull, Ambulocetus, Middle Ear

• School: McGill University
• Department: Biology
• Course: BIOL 111
• Professor: Rudiger Krahe

Document Summary

Biol 111 lecture 20 mammals i: hair, milk, & placenta. Lecture date/time: nov 17th, 2015 / 10:35-11:25 am. Mammary glands (milk production fat & protein) Divergence between reptilian & mammalian-like amniotes occurred during carboniferous (~350 mya) Skull morphology is a key characteristic used to identify relatedness among amniotes. Key difference between skulls is presence, size, & number of temporal fenestrae = holes that provide more surface area for muscle attachment. Early mammals were small, arboreal, shrew-like insectivores, and were nocturnal. Had larger brain relative to size, middle ear bones were separated & derived from jaw. Learned a lot based on middle ear of fossils. Different morphological state of middle ear of mammals: Heightened senses in early mammals relative to reptiles. Development of middle ear allowed mammals to hear at higher frequencies than reptiles. Larger olfactory bulbs have been detected through ct scans of fossils (sense of smell)