Models on WHY?• Why we became bipedal (6 hypotheses)

Efficient bipedalism as the primary form of locomotion is seen only in hominins.

Origins of all these bipedalism tendencies?

Primate Evolution• Where all the humans, australopithicines,

monkeys, apes, homo habilis, tarsiers, lorises, bush babies, Neandertals, hobbit humans, etc. came from…

• Millions of years ago right after the dinosaurs died…

The end of the Cretaceous period 65.5 mya

Paleocene 65 myaPlacental mammal radiation

• Earliest primates

Eocene 55-35mya

• More than 200 recognized fossil primate species.

Eocene 55-35 mya

• More than 200 recognized fossil species.

Darwinius, from the Messel site in Germany, discovered in 2009

and dates to ~47 mya.

Eocene Primates Foramen magnum position =

whether the body is habitually horizontal (like a horse) or vertical (like a monkey).

During the Eocene, the foramen magnum in some primate species was beginning to move from the back of the skull towards the center.

Suggesting…Holding their bodies erect while hopping and sitting, like modern lemurs, galagos, and tarsiers.

Eocene Era primate and modern human skulls

Oligocene

• “Rafting” Africa-> South America ~34 mya early in the Oligocene

• By this early point in the Oligocene, continental drift had separated the New World from the Old World.

• New and Old World monkeys branch off here, 35 million years ago.

Oligocene• Approximate position of the continents during the beginning of the

Oligocene

Oligocene Primates from Fayum

• Apidium – Primitive dental

arrangement suggests near or before evolutionary divergence of Old and New World anthropoids

– Small, squirrel-like fruit and seed eating, adept at leaping and springing

Walking with the Beasts (BBC) “Whale

Killer”

Egypt’s FayumEgypt’s Fayum

Today, it’s a ~550 square Today, it’s a ~550 square mile lush “oasis” basin in the mile lush “oasis” basin in the desert south of Cairodesert south of Cairo

During the Eocene and During the Eocene and Oligocene, the Faiyum was Oligocene, the Faiyum was forrestedforrested

At the beginning of the At the beginning of the Miocene, the Faiyum had Miocene, the Faiyum had become a dry hollowbecome a dry hollow

Oligocene Primates from Fayum cont.

• Aegyptopithecus (genus)– 35-33 mya– Largest of Fayum

anthropoids, roughly the size of a modern howler monkey (13-18 lbs)

– Short-limbed, slow-moving