Concepts for review, Midterm 2
Major Trends in Primate Evolution:
--body size increase/’
--relative brain size increase
--emphasis on vision
--manual and pedal grasping
--exploitation of arboreal substrates
--reduction in number of teeth
*early primates in the Paleocene, Plesiadapids:
Paleocene Epoch: 65-55 Million years ago, Development of Protoprimates,
northern latitudes, rodent-like (mostly).
*Adapid and Omomyid primates in the Eocene:
Eocene Epoch: 55-35 million years, 1st euprimates, warming, northern latitudes
(mostly), lemur- and tarsier-like.
*first monkeys from the Oligocene
Oligocene Epoch: 35-25 Million years, 1st anthropoids, Old World; 1st New
World monkeys; cooler.
New World primate origins:
--first appearance at end of Oligocene, ca. 28-26 Myr (Branisella, Bolivia)
--major adaptive radiation between 20-12 Myr
--most modern lineages can be traced back to the middle Miocene, ca. 16-11 Myr
--intercontinental dispersal from Africa, via vegetation mat rafting?
Fayum primates such as Proteopithecus; close relationship between S. American
rodents and African porcupines)
--Pleistocene extinction event
fossil apes in the Miocene
Miocene Epoch: 25-5 million years ago, Apes diversify; 1st Old World monkeys;
hominids originate; warming
Fossil Hominids –
1. Methods of dating fossils
*radiometric dating: is a technique used to date materials, usually based on a comparison
between the observed abundance of a naturally occurring radioactive isotope and its
decay products, using known decay rates. It is the principal source of information
about the absolute age of rocks and other geological features, including the age of the
Earth itself, and can be used to date a wide range of natural and man-made materials.
Among the best-known techniques are radiocarbon dating, potassium-argon dating and
uranium-lead dating. By allowing the establishment of geological timescales, it provides
a significant source of information about the ages of fossils and the deduced rates of
evolutionary change. Radiometric dating is also used to date archaeological materials,
including ancient artifacts.