Chapter 5
Macroevolution: Processes of
Vertebrate and Mammalian
Evolution
Chapter Outline




The Human Place in the Organic World
Principles of Classification
Definition of Species
Vertebrate Evolutionary History: A Brief
Summary
Chapter Outline



Mammalian Evolution
The Emergence of Major Mammalian
Groups
Processes of Macroevolution
The Human Place in the Organic
World

Classification groups life forms into
categories showing evolutionary
relationships.
 Example - human classification
–
–
–
–
–
Kingdom: Animalia
Subkingdom: Metazoan
Phyla: Chordata
Subphyla: Vertebrata
Class: Mammalia
Taxonomic Concepts

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:
– 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
Ecological
Species
Concept
Key aspect is the ability individuals
have to identify members of their
own species for mating purposes.
A species is a group of organisms
exploiting a single niche. Natural
selection separates species from
one another.
Evolutionary “Trees” Showing
Development of Vehicles
Cladogram of Relationships of
Birds, Dinosaurs, and Other
Terrestrial Vertebrates
Evolutionary Relationships
of Birds and Dinosaurs
2 Approaches to Interpretations of
Evolutionary Relationships
Speciation Model: Branching
Evolution
Geological Time Scale
ERA
PERIOD
CENOZOIC Tertiary
Began
m.y.a.
1.8
Quaternary 65
EPOCH
Began
m.y.a.
Holocene
0.01
Pleistocene 1.8
Pliocene
Miocene
Oligocene
Eocene
Paleocene
5
23
34
55
65
Geological Time Scale
ERA
MESOZOIC
PALEOZOIC
PERIOD
Cretaceous
(Began m.y.a.)
136
Jurassic
Triassic
190
225
Permian
Carboniferous
Devonian
Silurian
Ordovician
Cambrian
280
345
395
430
500
570
Continental Drift
Geological Eras

Paleozoic
– The first vertebrates appeared 500 m.m.y.a.

Mesozoic
– Reptiles were dominant land vertebrates.
– Placental mammals appeared 70 m.Y.A.

Cenozoic
– Divided into two periods: Tertiary and Quaternary
and 7 epochs: Paleocene, Eocene, Oligocene,
Miocene, Pliocene, Pleistocene and Holocene.
Mammalian Evolution

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

Monotremes
– Primitive, egg laying mammals

Marsupials
– Infants complete development in an eternal pouch

Placental
– Longer gestation allows the central nervous
system to develop more completely
Early Primate Evolution



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

Apidium
– Small, primate that may lie near or before
the evolutionary divergence of Old and
New World anthropoids.

Aegyptopithecus
– 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:
– African forms (23-14 m.y.a.)
– European forms (13-11 m.y.a.)
– Asian forms (16-7 m.y.a.)
Lateral View of the Brain
Reptilian and
Mammalian Teeth
Genus and Species



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.