Human Evolutionary Development Eocene Epoch Oligocene Epoch Miocene Epoch

Geologic Time & Human Evolution

The Eocene epoch (55-35 mya) Eocene warmest epoch of Cenozoic NW Tenn., trop. rain forest, like Panama First appearance of many modern orders of mammals As mentioned, rodents First bats, whales, modern ungulates and carnivores Most important for us, the first P.O.M.A. Primates of Modern Aspect Two major groups: the adapids and omomyids Both groups at the most primitive grade of adaptation

The Adapids First appear in early Eocene (50-55 mya) Possibly in Asia in late Eocene Found in both Europe and N. America Early forms more numerous in Europe Three important genera: Cantius - earliest adapid Only early Eocene genus from N. Am. & Eur. Adapis - lemur-sized European form Named & described by Cuvier (1821) Notharctus - lemur-sized American form Very lemur like

The Omomyids First appear in early Eocene (50-55 mya) Found in Europe, N. America and Asia Early forms more numerous in N. America Important genera: Teilhardina - earliest omomyid From Belgium Rooneyia - from late Eocene of N. America they were very Tarsier or galago like

Adapids vs. Omomyids

The big question: Which group gave rise to the Anthropoids (Human and Great Ape Line)? Most fossil features point to the adapids Omomyids are good ancestors for tarsiers

The Oligocene epoch (35-25 mya) - the first Anthropoids The Fayum depression - Egypt, 60 mi. SW of Cairo Early Oligocene (ca. 33 mya) 2 genera: Apidium - squirrel-sized arboreal quadruped Dental formula: 2-1-3-3 Could be ancestor to both N.W. and O.W. Aegyptopithecus - most important of Fayum finds Dental formula: 2-1-2-3 relatively large brain Large bodied, ~12 lbs. on average Substantial canine sexual dimorphism Heavily-muscled, arboreal quadruped

Aegyptopithecus

Aegyptopithecus Reconstruction

Old and New World Monkeys Aegyptopithecus is best candidate for ancestral Old World Monkeys Adaptation: like modern monkeys What about the New World Monkeys? Earliest fossil evidence from Bolivian Oligocene Geologically same time as Fayum, ~33 mya

Miocene Primate Evolution The Miocene epoch (25-5 mya) - "The Golden Age of Apes" Two major hominoid radiations The dryopiths - Early to Middle Miocene (25-15 mya) The ramapiths - Middle to Late Miocene (15-5 mya)

The Dryopiths Distribution (geographic and temporal) Important genera Most forms from E. Africa Some Mid-Miocene forms from Europe Important genera Proconsul - Early Miocene, E. Africa Dryopithecus - Mid-Miocene, W. Europe Morphology Cranial features Generalized No major chewing specializations Post-cranial ("below the head") features Body size: monkey to _ gorilla-sized Limb proportions - monkey-like Fore-limbs not elongate relatively short fingers & toes

Dryopithecus

Dryopithecines Reconstruction

The Ramapiths Distribution (geographic and temporal) Ancestors? Most widespread hominoids ever (until us) Turkey, Hungary, Greece, Pakistan (14-8 mya) Later in China and mainland SE Asia (~8-0.5 mya) Ancestors? Probably a Middle Miocene, E. African form Kenyapithecus: a good ancestor, ~14 mya big powerful jaws thick molar enamel Most important genus Sivapithecus (includes Ramapithecus)

General Ramapith Morphology Dentition similar to Dryopiths One major dental character is thick molar enamel Cranial features More ape-like, chewing specializations Post-cranial features Not much evidence; seemingly more ape-like More mobile shoulder joint Possibly more terrestrial than Dryopiths

Specific Sivapithecus Morphology "What great ape would it resemble?" Later Asian forms Cranial features mirror Orangutan Sloping lower face/jaw It's best interpreted as ancestor of Pongo (Orangutan)

Sivapithecus

One other interesting ramapith genus: Gigantopithecus Found in Pakistan and China Dates to 9-0.5 mya, latest surviving Ramapith Huge jaws and teeth; only parts found May have been 6-9 ft. tall, >600 lbs! What caused its extinction? Maybe early humans More mundane: Giant Panda Same niche, large-bodied bamboo eater Maybe NOT extinct! Abominable Snowman & Sasquatch ???

Gigantopithecus

Last Common Ancestor? Unable to determine exact specimen as yet. Molecular data suggests split occurred between 6 and 5 million years ago. Extensive genetic diversity in hominoids during the Miocene.