Placentals
Give birth to well developed young
Marsupials
Give birth to underdeveloped young
Monotremes
Egg-laying mammals
Synapsid
United by features in the skull also found in mammals (but not reptiles, dinosaurs or birds)
1. temporal fenestra
2. differentiation in tooth morphology
3. jaw consisted of fewer bones compared to reptile group
4. second palate appears
Palate
the roof of the mouth, separating the cavities of the nose and the mouth in vertebrates
Therapsids
- feet are directly under the body
- first evidence of hairs in fossil record
- more holes/space in the bones (for greater blood flow)
- baby teeth being replaced by adult teeth
Cynodonts
- Evolution of lactation
- Cheek teeth : to cut up food
- Jaw muscles moved outside the brain case
- Evolution of ear bones
Diurnal
Active during the day
Nocturnal
Active during the night
Crepuscular
Active during twilight
Nocturnal bottleneck hypothesis
these species could survive only by avoiding daytime activity during times in which dinosaurs were the dominant predator
Miocene cooling
Temperatures dropped globally by 5 degrees celsius around 40 million years ago
- radically changed the dominant plant life
Cloaca
Single opening for reproduction and waste disposal
Sociality
Taking care of our young for so long
