Stratigraphic correlation. Old Earth, Changing Earth. Plate Tectonics. A105 Fossil Lecture. Cenozoic Era: Age of Mammals. Tuff A. Tuff Q.

Transcription

1 Stratigraphic correlation Old Earth, Changing Earth Tuff A Tuff A MA Tuff Q Tuff Q Tuff B Tuff C MA MA Tuff C Plate Tectonics Cenozoic Era: Age of Mammals Text pp 128-=130 5 my 23 my Miocene Epoch Oligocene Epoch 37 my 53 my 65 my Eocene Epoch First primates Paleocene Epoch 1

2 Primate Family Tree Living Prosimians Living Anthropoid Primates Early fossil primates ~55 mya Splitting of branches or clades called cladogenesis Ancestral primate Early Mammal Early prosimians Early fossil prosimians ~30 mya Prosimians colonize Madagascar Madagascar Lemurs extinct everywhere except Madagascar Lemur diversity today 2

3 Madagascar Founder Effect ancestral Prosimian colonizers Reproductive Isolation Divergence from other populations Adaptive Radiation evolution into diverse ecological niches Primate Family Tree Living Prosimians ~30 mya Ancestral primate Living Anthropoid Primates Split between New world (retain primitive dental pattern) and Old world anthropoids (lose teeth) ~55 mya Early Mammal Primate macroevolution Primates die out New World monkeys evolve mya Anthropoids evolve Specialized Adaptation General Primate Traits: Primate Family Tree Living Prosimians ~30 mya Ancestral primate Living Anthropoid Primates ~45 mya primitive mammal traits: Early Mammal ~55 mya Early Old World anthropoids Age of Mammals 5 my 45 mya 23 my 37 my Miocene Epoch Oligocene Epoch Radiation of Anthropoid primates 53 my Eocene Epoch 65 my Paleocene Epoch First primates 3

4 Fayum fossil site First Anthropoid primates Fayum, Egypt: ~35 mya Text p 131 Egypt mya Many species of Anthropoid - Mostly small, arboreal quadrupeds - Varied dental patterns Desert Primates? NO! Plant fossils = Aegyptopithecus Primitive anthropoid primate Primitive (ancestral) traits: - Grasping quadruped Small brain Forest & swamp Aegyptopithecus Aegyptopithecus Ancestral to apes? Derived traits: - Complete eye socket Diurnal (small eyes) Teeth Y-5 molars male Body size 15 lbs Sexual dimorphism female 4

5 Age of Mammals Early Miocene mya Africa = island Animals isolated 5 my 23 my Miocene Epoch Diversification of apes & monkeys Oligocene Epoch Radiation of Anthropoid primates 37 my Eocene Epoch 53 my First primates 65 my Paleocene Epoch Early Miocene Rusinga Island, East Africa Planet of the Apes! Early Miocene forest At foot of volcano Africa only Very diverse - Big & small Few monkeys Volcanic sediments K/Ar mya Proconsul Proconsul Proconsul Large brain (ape-like) Teeth of a Fruit-eater But primitive (not ape-like) 5

6 Primitive traits: - arboreal quadruped - thorax, wrists Evolutionary MOSAIC Derived Ape-like traits: - tail, back, legs - shoulder, arm Fossil detective work CAUTIONS: Few & fragmentary fossils ID based on comparative anatomy Not all anatomical similarities = relationship - Shared primitive traits - Convergent traits - Diet / teeth 17 mya: Link-up! Climate change Long-term cooling trend Forests break up Drier More seasonal 6

7 Middle-Late Miocene Savanna woodlands spread 17-5 mya African & Eurasian animal communities mix Apes: out of Africa for first time Climate: environments dry out Forests break up - early ape habitats disappear New habitats Monkeys diversify & thrive Middle-Late Miocene fossil ape sites Pakistan Smaller pockets of forest Apes adapt & evolve More specialized Branch into different lineages Many go extinct Siwalik beds Pakistan Sediments: Streams Volcanic ash K/Ar method 15-8 mya Fossils Ape! No ordinary ape?! Broad, flat molars U-shaped jaw Small canine socket 7

8 Ramapithecus! Hindu deity Ramapithecus! Tool use = biped Small canines = tool use? Biped = first hominid?! 15-8 mya 8