ANTA01H3 Lecture Notes - Lecture 6: Catarrhini, Three Steps, Adapidae

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Published on 9 Oct 2015
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ANTA01- Lecture 6 Nonhuman Primate Evolution: The Ape-Hominin Transition
CONTINUATION OF LECTURE 5
Family Hominidae - Great Apes & Humans
Three genera of great apes
1. Genus Pongo: Orangutans
2. Genus Gorilla: Gorillas
3. Genus Pan: Chimpanzees & Bonobos
Knuckle-walking
Gorillas, chimpanzees, & bonobos
Orangutans
Quadrumanus (4 handed) locomotion
Asian great apes
They are solitary
Arboreal
Frugivore
They are lightly distributed (found only on the islands of Borneo & Sumatra)
Gorillas
Only found in Africa
Weight varies
o Males can weigh up too 300 pounds
Very large
All of the great apes make nests on the group to sleep (group dwelling)
Diet includes leaves, shoots, stems, and some fruit
Largest of the great apes but have a reputation for being gentle giants
Uni-male & multi-female or a couple of males and several females (quite small
social organizations)
Not widely distributed
Just as susceptible to Ebola like humans and this has wiped out many gorillas
Around the age of 15, they get sexually selected male characteristics (example:
silver back)
Chimpanzees
Are bonobos
African
Terrestrial & Arboreal (Sleep in trees & make nests in trees)
Omnivores
Make & use tools
Both bonobos & chimpanzees
o Males stay in communities and females move between communities
Differences between bonobos & chimpanzees
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o Chimpanzees are male dominant and extremely aggressive
o Bonobos are female dominant (very sexual)
Bonobos (below river) were separated by the Congo river with the common
chimpanzees (Above river)
Bonobo
Sometimes called pygmy chimpanzees
Spend more time walking on two legs (more bipedal behaviour)
Strong bonds among females
Use sex to ease tensions
Post-Test
Question: What is the main mode of locomotion of the lesser apes?
Answer: Brachiation
Post-Test
Question: What is the function of ischial callosities?
Answer: None of the above
LECTURE 6
Objectives
Period of primate diversification
Nonhuman primate fossils that predate hominins
Ape-hominin transition
What makes us human?
Geological Time Scale
Mostly everything happened in Cenozoic time scale
Continental Drift & Climate Change
The arrangements of the continents have changed considerable over time
o Over 200 million years, all the contents were joined in one huge land mass
(Pangea)
o Over 130 years ago, it broke into an upper portion (Laurasia) and a lower
portion (Gondwanaland)
o 65 million ago, broke into North America, Eurasia, Africa, South America,
India, Australia, Antarctica, & Madagascar
Break of continents caused major geographic barriers and caused break up of
populations
Certain species became isolated and separate lineages were formed
The size & orientation of continents affected climates
o Example: larger masses are colder
Climates have been getting colder
Very warm in Paleocene & Eocene (age of strephsihines)
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Miocene: real dominance of apes
Hominins in Pliocene
Now, living in the age of monkeys (more monkeys now than the past)
Recently, climate has been very variable (ice ages and warmer trends)
Early Mammals
Evolved first from therapsids (diverse group of reptiles, warm blooded, and
covered with hair)
They are mouse sized animals
Nocturnal
We had internal fertilization but we still laid eggs until the end of the Mesozoic
time era
Primate Ancestors
End of Mesozoic: a big change in vegetation
o Gymnosperm were the dominant plant but this dominance was shifted to
angiosperm
o Primates were one group who evolved to fir the new ecological niche
o Gymnosperms are still around
Plesiadapiforms
o Pre-primates
o Quite a few specimen’s now
o Vary from tiny shrew like creatures to marmite sized creatures
They have been demoted from primates because they had eyes on
the side of their face
o They have claws instead of big nails
o Highly developed in their sense of smell
o Nocturnal quadrupeds
o Ate seeds & insects
o And lacked modern day primate characteristics
Establishing Phylogenies
We don’t know our first primates
Having fossils & assigning them to a species is only the first step
Second step is to establish relationships between fossil species and establish
ancestor-descendant’s lines
Result is very few unequivocal relationships, partly because of the luck of the
draw in finding fossils. Not all species give rise to descendants.
First True Primates Resemble Prosimians
2 kinds of families in the Eocene
1. Omomyids
o Look like tarsiers
o They have elongated tarsal bones
o Nocturnal
o Insectivorous
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