Lemur Symphysis Chapter 7 Summary

Week Seven Notes:
The Stepsirhines: Lemurs and Lorises
Prosimians(Same thing as Stepsirhines): Lemurs, Lorises, Tarsiers:
Most primitive of the primates
Exhibit the fewest derived traits (as a group) of all primates
Ancestral Characteristics (ie. Inherited from mammals)
• Rely more on olfaction
• Moist noise and long snout
• Eyes slightly more lateral
Classification of Prosimians: Lemurs, Lorises, and Tarsiers
Order- primates
Suborder: Strepsirhines (used to be Prosimians)
• Means “wet-nosed”
• Lemurs and Lorises
Strepsirhines: Shared Anatomical Features
1. Postorbital ring/bar (derived)
2. Unfused frontal bone (ancestral)
3. Unfused Mandibular Symphysis (ancestral)
a. Mandibular symphysis at the midpoint of the chin
4. Tooth
Unfused frontal (ancestral)
2. Unfused Mandibular symphysis (ancestral)
3. 2-1-3-3 Dental formula
4. Bicornuate Uterus
Tarsiers: Traits not shared with Strepsirhines
1. Postorbital ring
2. Dental comb
3. Tapetum Lucidum
Tarsiers more like monkeys in their genetics
Primate Fossil Ancestry: Events Preceding Primates
Ca. 500 MYA: first vertebrates in fossil record
Ca. 250 MYA: Pangea II forms- nearly all land is one big continent
Ca. 125 MYA: Pangea is split into Northern and Southern halves

Ca. 125 MYA
• Northern continent is Laurasia o North America, Greenland, Europe, Asia (minus India)
• Southern Continent is Gondwana o South America, Africa, Antarctica, Australia
• Adaptive radiation of angiosperms underway o Angiosperm-flowering plants o Important for later primate evolution (fruits/insects)
• Marsupials have recently evolved
Events Preceding Primates cont:
Ca. 70 MYA: first placental mammals in fossil record
Ca. 65 MYA: Mass extinction of most dinosaurs
50% of animal genera go