Geologic Time Scale

Relevant to Primate & Hominin Evolution

Animal life diversifies starting in the Phanerozoic

Marine invertebrates

Firstvertebrates

Arthropods

Age of Fishes, 1st amphibians

& insects

Age of amphibians, 1st reptiles, 1st great

insect radiation

570 mya 500 430 395 345 280 225 190

Cambrian

Expansion of reptiles,decline of amphibians

Ordovician Silurian Devonian

Carboniferous

Permian

TriassicJurassic & Cretaceous

Paleozoic Era Mesozoic Era

225 190 136 65

1st Mammals (Monotremes) & dinosaurs

Age of dinosaurs1st birds

1st flowering trees (angiosperms)!st Marsupials, Placental mammalsDinosaurs vanish @ 65mya

Mammals, birds, insects

flourish

Triassic Period Jurassic PeriodCenozoic EraCretacous

Period

Mesozoic Era

Primates finally start to enter the scene, 65 mya

65 54 34 23 5

Paleocene Epoch Eocene Miocene

PliocenePleistocene

Oligocene

Oldest primates(?) PlesiadapiformsFirst Primates Evolve

Prosimians thrive1st AnthropoidsEvolve

Monkeys &1st primatesin South America

1stHominoids

HumansHominins

1.8 mya

Cenozoic Era: 65 my - present: 3 Periods: 7 Epochs

Holoocene

10 kya

Mammalian Evolution: A summary• Paleozoic: Devonian: First mammal-like reptiles (Therapsids)• Mesozoic: Triassic: First mammals (Monotremes)• Mesozoic: Cretaceous: First Marsupials & Placental

mammals, • Cenozoic

– Paleocene: Plesiadapiforms & 1st true primates

– Eocene: Prosimians thrive + first Anthropoids– Oligocene: Anthropoids spread + first Hominoids– Miocene & Pliocene: First Hominids (7-1.7 mya)– Pleistocene: First Hominines (1.7-0.1 mya)– 200,000-100,000 ya: First Humans– Holocene: 10,000 ya: History

Over last 200 my, the earth rearranged itself

Continental drift is important part of human history because it changed global climates

25C = 77 F10C = 50 F

Temperatures have declined steeply from Eocene to presentHuge fluctuations in last 5 my

The Mesozoic

• Triasic (225 mya)– Pangea was a single continent– Dinosaurs & small mammals evolve– Pangea HUGE land mass = cold winters, hot moist summers

(Wisconsin)• 200 mya Pangea starts breaking up --> Laurasia & Gondawana

• Oceans are barriers to gene flow = new species form– World gets warmer when continent splits– Dinosaurs and mammals evolve in this warmer world– Rise of angiosperms = fruits bearing trees = new foods

The Cenozoic: Paleogene Period

• Mammalian adaptive radiation to fill angiosperm niches• Paleocene wet & warm• Eocene wetter & warmer

– Tropical forests– SA isolated from NA & Europe = new species– Primates (prosimians) highly successful & diverse– First anthropoids appear

• Oligocene getting colder & drier, more seasonal variation– Mostly modern continent positions– SA still separate– Cold water currents cooling earth but Africa & SA

tropical forests– Monkeys prosper, first hominoids appear

The Cenozoic: Neogene Period & Quaternary

Neogene Period• Miocene warm & moist at beginning, got colder & drier

– Forests retreating = open woodland habitat– Himalayas form = block warm & create cold air

currents– Rift valley forms = rain shadow & dry savannah in

Africa– First hominins evolved (late Miocene)

• Pliocene begins frequent temperature fluctuations– Hominins diversify

Quaternary Period• Pleistocene: extreme temperature fluctuations

– Modern humans evolve