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Primate Evolution
5 November, 2007
Time, time, time….
Origin of
life
Earth’s
origin
Themes
Bush analogy (vs. ladder)
“Extinction is the rule”
Incompleteness of the fossil record
“Once we were not alone”
The nature of the evidence


Fossils
Molecular- protein/DNA
Class- Mammalia
Derived from a branch of the reptiles- the
therapsids
~200 M ybp
Class- Mammalia
Characteristics

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Hair
Mammary Glands (w/ or w/o nipples)
“Warm blooded”
Egg layers- earliest form= “monotremes”
Lots of unique anatomical features (1 aorta, 3
middle ear bones, one jaw bone (dentary), etc…)
Mammals, continued…

Anatomy
One jaw bone
3 middle ear bones
Specific arterial
structures
Initially small, rat-like, nocturnal insect
eaters
Earliest Mammals
Modern descendents- platypus (of
Australia) & echidna (of New Zealand)
“Advanced” Mammalsthe “Placentals”
~ 100 M ybp- “Age of the Dinosaurs”
(Cretaceous era)
(older fossil?- ~ 130 M ybp, 1 meter in
length)
“Live bearing mammals”


Internal development
Some form of connection between mother
and fetus= “placenta”
Two parallel lineages:
Marsupial mammals- kangaroo, wallaby,
opossum

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Young “born” only partially developed
No eggs- internal (initial) developmentrudimentary placenta
Well-developed nipples- young attach to
complete development
Live bearing Mammals
“Eutheria”


True placenta
Offspring spend longer developing in mother
The reality of the situation at
~ 65 M ybp
Mammals (monotremes, marsupials &
eutherians) were all a very small part of
animal diversity
Eutherians represented by a very small
number of small, nocturnal, shrew-like
animals
The “K/T Boundary” (cretaceous/tertiary)
The reality of the situation at
~ 65 M ybp
The “K/T Boundary” (cretaceous/tertiary)- one of many
historical “Mass extinctions” (many living groups,
including the dinosaurs)
Mammalian diversification
Explosive diversity of mammalian types in
“vacuum” of rapid dinosaur extinctionsespecially eutherians
~60 M ybp
Primates (taxonomic Order)
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Tree-dwelling
Omnivorous
Branchiate- swing by arms
Dexterous hands
Claws replaced by nails
Opposable thumb
Forward-facing eyes, binocular vision
Parental care
~ 58 M ybp
Ancestral Primate
“Wet-nosed” primates
• Mostly nocturnal
• Tree-dwelling
Lemurs
“Dry-nosed” primates
• Mostly diurnal
• Specialized hands and
feet for grasping
Tarsiers + Monkeys & Apes
(a.k.a. “Simians”)
First- cat-sized and arboreal
~ 40 M ybp
Ancestral Simian
Atlantic Ocean
New-World Monkeys
N/S America
• Long prehensile tail
• Flat nose
• Tree-dwelling
• Mostly nocturnal
Capuchin, Marmosets,
Howler monkey
Old-World Monkeys + others
Africa & Asia
• Simple, no tail
• Narrow nose
• Tree-dwelling
• Mostly diurnal
• Flat fingernails
Baboon, Macaque, Great
Apes
~ 25 M ybp
Ancestral Old World Monkeys, et al
(Apes) “Hominoids”
• Mostly arboreal
• Africa, Asia
• Other anatomical
features
Gibbon, Great Apes
Old-World Monkeys
Baboon, Macaque, Proboscis
Monkey
~ 18 M ybp
Ancestral Hominoids
“Lesser Apes”
• Tree-dwelling
• Strong brachiating
Gibbons
The “Hominidae”
Humans +Great Apes
The “Hominidae”
The “Hominidae”
The “Hominidae”
~ 14 M ybp
Sivapithecus (Ramipethecus)- fossil
~ 14 M ybp
Initially thought to be an early “homininae”
Orangutans
Asia
The “Homininae”
Evolved in Africa:
Gorilla, Chimp, Pygmy
Chimp, Human
The “Homininae”
The “Homininae”
~ 7 M ybp
Gorillas
2 (4?) species
• Knuckle-walk
• Intelligent
Western & Eastern
species (w/ subspecies)
The “Hominini”
Humans, Chimpanzee,
Pygmy Chimpanzee
(Bonobo)
The “Hominini”
The “Hominini”
6- 7 M ybp
Molecular evidence“Molecular clocks”
Antibody specificity
DNA hybridization
Chimpanzee
Larger, stockier
More aggressive
Male-dominated
social groups
Bonobo
Gracile
More cooperative,
more sexual
Female-dominated
Social groups
The “Hominids”
Humans + fossils
leading to modern
humans
The “Hominids”
Bipedal
Large brain
Small canine
teeth
Later:
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Tool production
Language
Art
BREAK TIME
B
D
G
E
F
A
Raymond Dart- 1924
Australopithecus africanus
Donald Johansen
Australopithecus afarensis
1994East Africa & Chad
Importance of A. afarensis
“Gracile”
lineages
“Robust”
lineages
“Once we were not alone”
B
Chimp
E
G
D
Gorilla
C
Homo sapiens as the “wanderer”
The “out of Africa” theory
Years before present (byp)
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