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Chapter 9

ANT203H5 Chapter Notes - Chapter 9: Carpolestes, Simian, Oligocene

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Esteban Parra

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Notes From Reading
Early Primate Evolution
-Primates evolved during the Cenozoic era, which is the past 65.5 million years
-Epoch – A subdivision of a geologic period
Overview of Early Primate Evolution
-An adaptive radiation of primate-like mammals led to the origin of what we would call
“true primates”
-The primate-like mammals showed evidence of an initial adaptation to life in trees
-Most of these species died out, but some evolved into primitive primates, which were
fully adapted to living in the trees
-These primates then underwent another adaptive radion, and although many of these
early primate species became extinct, some species survived to ultimately evolve into the
different lines of modern strepsirhines
-Some of the early primates evolved into early haplorhines, including the anthropoids
-Subsequent adaptive radiations led to separate groups of New World monkeys, Old World
monkeys, and the first primitive apes
Primate Origins
-Continental Drift and Primate Evolution
oContinental Drift – The movement of continental land masses on top of a
partially molten layer of the earth’s mantle that has altered the relative location of
the continents over time
oMost of the fossil evidence on primate origins comes from the deposits over 55
million years ago in North America and Europe of a group of insectivores known
as the primate-like mammals
oRoughly 230 mya, all the countries were joined together as one large land mass
oBy 180 mya, this large mass had split in two: one containing North America,
Europe, and Asian, and the other containing South America, Africa, Australia,
and Antartica
-The Primate-like Mammals
oPaleocene epoch – The first epoch of the Cenozoic era, dating between 65.5
million and 55.8 million years ago. The primate-like mammals appeared during
the Paleocene.
oPlesiadapiforms were small creatures, that were quadrupedal mammals whose
arms and legs were well adaptive for climbing; now not considered true primates
oCarpolestes simpsoni - A species of primate-like mammals that had some
derived primate traits, such as a grasping foot and an opposable big toe. This
species is intermediate in many respects between primitive primate-like
mammals and true primates.
oBecause Carpolestes shows grasping hands but not stereoscopic vision, it appears
clear that grasping hands came first in the evolutionary sequence of primate
oThe fact of grasping hands, combined with dental evidence pointing to a diet of
fruits, supports a model of primate origins whereby Carpolestes evolved grasping
hands to allow successful feeding on fruits and flowers at the ends of branches
oGrasping hands would have allowed Carpolestes to eat more food in less time
and to do so more safely
-The First Primates
oEocene epoch – The second epoch of the Cenozoic era, dating between 55.8
million and 33.9 million years ago. The first true primates, primitive prosimians,
appeared during the Eocene
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