Human Evolutionary Development Eocene Epoch Oligocene Epoch Miocene Epoch
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
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
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) • 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
The Ramapiths • Distribution (geographic and temporal) • 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)
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 ???
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.