Transcript Chapter 7 Mammalian/Primate Evolutionary History

Chapter 7
Processes of
Macroevolution:
Mammalian/Primate
Evolutionary History
Chapter Outline
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The Human Place in the Organic World
Principles of Classification
Definition of Species
Vertebrate Evolutionary History: A Brief
Summary
Chapter Outline
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Mammalian Evolution
Major Mammalian Groups
Early Primate Evolution
Miocene Fossil Hominoids
Processes of Macroevolution
The Human Place in the Organic World
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Classification groups life forms into categories
showing evolutionary relationships.
Example - human classification
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Kingdom: Animalia
Subkingdom: Metazoan
Phyla: Chordata
Subphyla: Vertebrata
Class: Mammalia
Taxonomic Concepts
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Homologies - structures shared through
descent from a common ancestor.
Analogies - structures used for the same
function that developed independently and are
not the result of common descent.
Homoplasy - the process by which similarities
can develop in different groups of organisms.
Cladistic Taxonomy
Groups species according to shared
derived characteristics:
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Primitive traits reflect the ancestral
condition.
Shared derived characteristics are shared
traits that weren’t present before the group's
appearance.
Approaches to the Definition of
Species
Biological Species
Concept
Species are defined by reproductive isolation.
Only members of the same species can
interbreed
Recognition
Species Concept
Key aspect is the ability individuals have to
identify members of their own species for
mating purposes.
Ecological Species
Concept
A species is a group of organisms exploiting a
single niche. Natural selection separates
species from one another.
Geological Time Scale
ERA
CENOZOIC
PERIOD
Began
m.y.a.
EPOCH
Began
m.y.a.
Tertiary
1.8
Holocene
Pleistocene
0.01
1.8
Quaternary
65
Pliocene
Miocene
Oligocene
Eocene
Paleocene
5
23
34
55
65
Geological Time Scale
ERA
PERIOD
(Began m.y.a.)
MESOZOIC
Cretaceous
136
Jurassic
190
Triassic
225
Permian
Carboniferous
Devonian
Silurian
Ordovician
Cambrian
280
345
395
430
500
570
PALEOZOIC
Geological Eras
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Paleozoic
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Mesozoic
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The first vertebrates appeared 500 m.m.y.a.
Reptiles were dominant land vertebrates.
Placental mammals appeared 70 m.Y.A.
Cenozoic
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Divided into two periods: Tertiary and Quaternary
and 7 epochs: Paleocene, Eocene, Oligocene,
Miocene, Pliocene, Pleistocene and Holocene.
Mammalian Evolution
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The Cenozoic era is known as the Age of
Mammals.
After dinosaurs became extinct, mammals
underwent adaptive radiation, resulting in
rapid expansion and diversification.
The neocortex, which controls higher brain
functions, comprised the majority of brain
volume, resulting in greater ability to learn.
Major Mammalian Groups
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Monotremes
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Marsupials
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Primitive, egg laying mammals
Infants complete development in an eternal pouch
Placental
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Longer gestation allows the central nervous system
to develop more completely
Early Primate Evolution
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Primate origins began in the placental mammal
radiation 65 m.y.a.
The earliest undoubted primates appear in the
Eocene epoch.
Most of our knowledge of primate Oligocene
evolution comes from a site in Egypt, the
Fayum.
Fayum Forms: Possible Roots of
Anthropoid Evolution
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Apidium
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Small, primate that may lie near or before the
evolutionary divergence of Old and New World
anthropoids.
Aegyptopithecus
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Largest of the Fayum primates with a small brain,
large snout, and none of the traits of Old World
monkeys or the hominoids.
Miocene Fossil Hominoids
Marked by a spectacular hominoid
radiation and could be called “the golden
age of hominoids”.
 Grouped geographically:
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 African
forms (23-14 m.y.a.)
 European forms (13-11 m.y.a.)
 Asian forms (16-7 m.y.a.)
Genus and Species
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Species is the most precise taxonomic level.
Genus is a group of species more closely
related to each other than to species from
another genus.
Members of the same genus share derived
characteristics not seen in other genera.