From Review Session 2 Flashcards
Three kinds of questions
- Make a list (provide 3-5 features that distinguish group x from y) (make clear what group you’re feature refers to) (Anthropoids have large brains vs Anthropoids have larger brains than prosimians)
- Fill in the blank
- (Very) short answer
List five features that distinguish anthropoids from prosimians
- Larger
- Diurnal
- No tapetum lucidum
- More orbital frontation
- Shorter snout
- More conservative teeth
- Larger brain
How did anthropoids get to the New World (Americas) from the Old World (Africa)?
Rafting (most likely)
Anthropoids in the New World =
Platyrrhines
Platyrrhines
- = New World Monkeys
- = “flat nosed” (circular nostrils)
- Break up into 4 groups
Callitrichines, Cebines, Atelines, Pithecines
General Platyrrhine Features
- Small-medium sized monkeys
- Dental formula = 2133 (for most) (Except Callitrichines)
- Purely arboreal
- SOME have specialized “Prehensile” tails (Atelines have prehensile tails)
Callitrichines
- The “odd” ones
- = Beautiful hair
- Marmosets, Tamarins, Goeldi’s Monkey
What are the distinctive features of the Callitrichines?
- Question 7
- Upper 1st molar has only 3 cusps (Simple molars)
- 2132 dental formula
- Digital claws
- Twins
- Tail NOT prehensile
Why twins? (Callitrichines)
- Selective agent predation
- Because of slides (next slide) caused COMMUNAL REARING SYSTEM, including multiple males cause wonder who is father (polyandry)
Callitrichines are considered “Phyletic dwarfs”…
- Small body size evolved as an anti-predation strategy
- Mother’s weights decreased faster than litter weight
- Thus, if they gave birth to single offspring, the infants would be relatively enormous
- This, divide the obstetric load in two … twins!
- Twinning required additional “care”
Adaptive Significance for polyandrous males (What does helping do?)
- Lactating females are stressed and don’t carry infants long distances
- If only single male present, he would have to carry infants all the time
- Lone reproductive pair would have a difficult time
- Thus, group should accept a second male
- To be feasible, both males should ultimately have equal chance of paternity and not be able to detect when females are ovulating
- Even if a male were not the father of EVERY infant he helped raise over his lifetime, he would raise enough of his OWN offspring to benefit from his helping behavior
Multiple helper males with …
Paternity uncertainty
The Common Marmoset
Callithrix jacchus
- 70-80% diet is gum (Bite bark hand from tree to get gum/sap/exodate) (Why claws evolved)
The Golden Lion Tamarin
Brought back from brink of extinction
Goeldi’s Monkey
- 2133 dental formula
- Claws
- Single birth
- Avoids gum
- Highest shearing crests of any platyrrhine (fungus)
Cebines species
Capuchin monkeys and Squirrel monkeys
Capuchin monkey (cebus)
- Organ grinder monkeys
- Very smart
- Named after capuchin monks
- Use stone tools to open nuts
- Number of features in brains of capuchins more similar to OWM than other NWM’s (in textbook) (See pg 2 for picture) (Given picture and point out capuchin) (ARCUATE feature in capuchin and OW not NW)
Squirrel monkeys (Saimin)
- Dental formula 2133
- Locomotion: Generalized arboreal quadruped and good leapers
- Frugivores and insectivores diet
- Multi male/female social system
- Male reproductive behavior: Increased estrogen fill with more water (retain) and bulk up and more vivid colors to be chosen by females
Pithecines
- Seed predators
- Massive jaws, front teeth provide grip and crack open large nuts with back molars
- Hard object specialists
Atelines
- Know how to answer who are the Atelines?
- Know how to answer what post cranial features unite Atelines (Prehensile tail)
- True prehensile tailed monkeys
- 2133
- Largest platyrrhines
- Dietary diversity
- Long hind/forelimbs