Overview of the Fossil Primates Chapter 9 Overview of the Fossil Primates

Map Showing Location of the Fossil Primates

Map Showing Location of the Fossil Primates

Geologic Timescale

Seven Epochs of the Cenozoic (65.5 - 0 mya) Paleocene (65 mya; primate-like mammals, aka Plesiadapiformes) Eocene (55.8 mya; first true primates, Prosimians) Oligocene (33 mya; early Catarrhines, precursors to monkeys and apes, emerge) Miocene (23 mya; monkeys and apes emerge, first humanlike creatures appear) Pliocene (5.3 mya; early humans diversify) Pleistocene (1.8 mya; early Homo develops) Holocene (0.01 mya; the present epoch)

General Prosimian Characteristics Smaller body size. Longer snouts with greater emphasis on smell. Eye sockets not completely enclosed in bone. Dental comb. Small simple premolars.

General Anthropoid Characteristics Nails instead of claws on all digits Loss of the artery running through the middle ear bone Fusion of the two sides of the mandible to form one bone Fusion of the two sides of the frontal bone Larger brain (in absolute terms and relative to body weight)

General Anthropoid Characteristics Generally larger body size Shorter snouts with greater emphasis on vision Back of eye socket formed by bony plate Less specialized dentition, as seen in absence of dental comb and some other features Larger and more complex premolars Derived square-shaped molars with new cusp

General Prosimian Characteristics Primitive triangle-shaped molars. Grooming claw. Artery running through the middle ear bone. Unfused mandible. Unfused frontal bone. Smaller brain size relative to body size.

Plesiadapiforms

Plesiadapiforms Plesiadapis features: Long tail Agile limbs Claws, not nails Rodent-like jaws and teeth Eyes at side of head Long snout No post-orbital bar

Carpolestids North American genera Elphidotarsius Carpodaptes Carpolestes Nearly complete skeleton of Carpolestes discovered in the Clarks Fork Basin of Wyoming. (a) Carpolestes as it was discovered. (b) Reconstructed skeleton (c) Artist’s rendering.

Carpolestes Nearly complete skeleton of Carpolestes discovered in the Clarks Fork Basin of Wyoming. (a) Carpolestes as it was discovered. (b) Reconstructed skeleton (c) Artist’s rendering.

Eocene Primates Fossil primates from the Eocene display distinctive primate features. The first unequivocal primates occur about 50 mya. There are two main groups identified: Adapids which are usually considered to be ancestral to modern Strepsirhines Omomyids which are (mostly) considered to be early Haplorhines

Adapids Northarctus Adapis Necrolemur Tarsius

Northarctus

Adapis

Omymids -Necrolemur and Tarsius

Madagascar Primates

Origins of Antrhopoids

Oligocene Primates The Oligocene (34–23 m.y.a.) yielded fossil remains of several species of early anthropoids. By the early Oligocene, continental drift had separated the New World from the Old World. It has been suggested that late in the Eocene or very early in the Oligocene, the first anthropoids arose in Africa and reached South America by “rafting” over the water separation on drifting chunks of vegetation.

Oligocene Primates

Apidium

Parapithecus Parapithecus belongs to the group of Fayum anthropoids that are most closely related to the ancestry of New World monkeys.

Aegyptopithecus Skull of Aegyptopithecus. This genus has been proposed as the ancestor of both Old World monkeys and hominoids.

Homunculus Skull of Homunculus, a middle Miocene descendant of the earliest platyrrhine radiation.

Victoriapithecus Skull of Victoriapithecus, the first Old World monkey.

New World Monkey vs. Old World Monkey Characteristics New World Monkeys Sideways facing nostrils Ring-like ear hole with no tube Dental formula of 2.1.3.3 Grasping tail Distribution: Mexico and South America Old World Monkeys Downward facing nostrils Tube-like ear hole Dental formula of 2.1.2.3 Ischial callosities Distribution: Africa, southern Asia and Japan

New World Primates

Rafting Hypotheses

Miocene Primates - Proconsul

Pliopithecus Pliopithecus, from the middle Miocene of Europe. The pliopithecoids were the first catarrhines to leave Africa. Since this skull is of a female, no sagittal crest is present, though strong temporal lines indicate the individual enjoyed a diet of hard plant items.

Dryopithecus Skull of Dryopithecus, the earliest European ape. The left side is reconstructed as a mirror image of the complete right side.

Ouranopithecus Ouranopithecus, possible ancestor of the African apes. Notice that the face shares many features with living African great apes, including large browridges and a wide distance between the eye orbits.

Gigantopithecus An artist’s rendering of Gigantopithecus enjoying a meal of the tasty, but tough, tropical fruit known as durian.

Simplified Chart