ANT100Y1 Lecture 4: LECTURE 4
October 15, 2015
Primate and Human Evolution
Lecture Goals
- General patterns of morphology and phylogenetics for fossil primates and hominins
- What a hominin is in terms of taxonomy
- Morphological trends in hominin evolution
o Bipedalism
o Expansion of brain size
o Changes in dental/cranial features
Time Frame and Climate
- Southern pole habitable continent millions of years ago
- Changes over time
- Fossil: biological material has been changed into stone
Major Epochs during Tertiary Period (Paleocene)
- End of age of dinos, beginning of Age of Mammals
- Systematically excluded from every continent as did many organisms
Paleocene Primates
- Geography and climate
o Look at map
o Antarctica joined with Australia
o Early on very hot in Antarctic
o Ocean and weather currents would have been very different
- Very different from present-day conditions
- Hotter, more humid
Paleocene and Primate-like Mammals: Plesiadapiformes
- Body Size: tiny, shrew-sized to size of small dog
o Similar looking to squirrels
- Niche: likely solitary, nocturnal quadrupeds; well-developed sense of smell
- Diet: insects and seeds
o Comparing teeth to modern day animals
- Used to be classified as primates because of primate-like teeth and limbs that are adapted for
arboreal lifestyle
o Classified as one of the first known primates
Recent: Plesiadapids Not Primates
- No postorbital bar
- Claws instead of nails
o Nails on a soft tissue bed
o Claws are attached to bone
- Eyes placed on side of head
o Stereoscopic vision for primates (front of face)
- Enlarged incisors
o Huge gap between front teeth and back teeth
- However, they weren’t using real scientific method but a scientific OPINION
o Phonetics using expert opinion not a scientific hypothesis
o BIASED
- Young scientist, Dr. Mary Silcox?
More Recent: Plesiadapids and others are Primates
- Cladistic analysis
- Hundreds of features
- Not bias but cladistics analysis
- Through genetic analysis, where primates began
- Genetic origin of our order
- Plesiadapids DO fall under primate
find more resources at oneclass.com
find more resources at oneclass.com
- Fossil evidence starts around 65 MYA but genetic evidence says 85 MYA
- Rewriting our understanding of evolutionary relationships
Major Epochs during Tertiary Period (Eocene)
- Fossil evidence says primates evolved in Paleocene
- Genetic evidence suggests they evolved earlier but they didn’t fossilize or we haven’t found it
- Eocene was a long time period 55.8 mya-33.9 MYA
- Ideal to be a mammal
- Plate tectonics begin
- Euprimates
o Look like modern primates
o First to be definitively identified as part of the primate order
Two Main Eocene Primate Families
- Adapidae
o Body size: 100g-6900g
o Diurnal and nocturnal forms
o Mainly arboreal quadrupeds, some were specialized leapers
o Smaller adapids ate mostly fruit and insects, larger forms ate more fruit and leaves
▪ Adapt to have large chamber in digestive tract to break down leaves etc.
▪ Remarkable adaptation in the early evolutionary
o Could have led to lemurs
- Omomyidae
o Body size of 45g-2500g
▪ Smaller group of early primates
o Some nocturnal other diurnal
o Omomyids thought to have been specialized leapers
o Teeth: adapted for eating insects and soft fruits, only few species were leaf eaters
o Could have led to Tarsiers
Major Epochs during Tertiary Period (Oligocene)
- 34 MYA-25 MYA
- Continued changes, continents close to where they are today, no land between N+S America
Oligocene Geography and Climate
- Climate fairly cool
- Ocean levels dropping
- More land exposed
- Temperate forests showing up
- Look for map
- Huge spike in global median temperatures
o Isolated islands forming
o Ocean currents change
o Sudden change instead of steady decline
Oligocene Primates
- Three haplorhine features
o Fused frontal bone
o Full postorbital closure
o Fused mandibular symphasis
- Three taxonomic groups
o Parapithecidae
▪ Fayum Depression, Egypt (larger in size)
o Propliopithecidae
o Platyrrhini
▪ Monkeys of central and South America
South American Primates
- Primates appear for first time in fossil record of South America towards late Oligocene
- Origins of South American primate unclear
- May have rafted over from Africa to eastern south America
find more resources at oneclass.com
find more resources at oneclass.com
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Document Summary
General patterns of morphology and phylogenetics for fossil primates and hominins. What a hominin is in terms of taxonomy. Morphological trends in hominin evolution: bipedalism, expansion of brain size, changes in dental/cranial features. Southern pole habitable continent millions of years ago. Fossil: biological material has been changed into stone. End of age of dinos, beginning of (cid:498)age of mammals(cid:499) Systematically excluded from every continent as did many organisms. Geography and climate: look at map, antarctica joined with australia, early on very hot in antarctic, ocean and weather currents would have been very different. Body size: tiny, shrew-sized to size of small dog: similar looking to squirrels. Niche: likely solitary, nocturnal quadrupeds; well-developed sense of smell. Diet: insects and seeds: comparing teeth to modern day animals. Used to be classified as primates because of primate-like teeth and limbs that are adapted for arboreal lifestyle: classified as one of the first known primates.
