5/19/2011 1 Cenozoic Life History Marine Invertebrates and Phytoplankton  Terminal Mesozoic extinction took out Ammonites, Rudists, most planktic forams, much of the phytoplankton  Survivors flourished and diversified – Foraminifera – large and small – Diatoms –great deposits of diatomite in Miocene – Corals form reefs in warm waters – Bryozoans (smaller and more ornate) thrive – Bivalves and Gastropods rule and become increasingly modern and familiar – Echinoids become more infaunal (Sand dollars)  Cenozoic is quite provincial due to changing ocean currents and latitudinal temperature gradient5/19/2011 2 Cenozoic Vegetation and Climate  Angiosperms came to rule, but gymnosperms and seedless vascular plants still numerous  Leaves with entire smooth edges and drip points indicate high rainfall, warm conditions – Paleocene of Colorado – Oligocene Florissant Beds of Colorado  Leaves with incised margins indicate cool, dry climates (Wolfe)5/19/2011 3 Paleocene-Eocene Thermal Maximum  Abrupt warming trend 55 mya  Ocean circulation disrupted, deep warm water, release of methane, greenhouse effect  Subtropical plant fossils in western North America indicate warmest period of Cenozoic in Paleocene and Eocene – Pan-tropical conditions Plants and Climate  Oligocene drop in temperature  General decrease in precipitation in midcontinent of North America – Grasslands with scattered trees (Savannah) – Grasslands (Steppe) – Seen in the teeth of mammals5/19/2011 4 Cenozoic Birds  Paleogene may be called the Age of Birds – 1st members of many modern groups evolved – Large predatory birds took over that niche before mammals  Miocene saw songbird explosion  Pleistocene large, flightless birds e.g. Moas, elephant birds  Flying birds rule the sky The Age of Mammals  140 my were small and not very diverse (Mesozoic)  Exploited the niches left by the dinosaurs and other reptiles – land, sea and air  Continued diversification at surprising speed throughout the Cenozoic5/19/2011 5 The Age of Mammals  Types of Mammals – Monotremes –egg laying Mammals – Marsupials – Carry embryo in pouch – Placental mammals – Have Placenta, give birth to live young5/19/2011 6 Paleocene Mammals  Some holdovers from Mesozoic, soon extinct  Archaic Mammals: insectovores, marsupials and multituberculates  New Mammals: rodents, rabbits, primates carnivores, ancestors of hoofed animals  Most mammals small; some orders became extinct  No match for giant birds Eocene and Oligocene Mammals  Larger  Ancestors of many living orders  Very large mammals included uintatheres and titanotheres  Oligocene drying produced diversification to more modern fauna5/19/2011 7 Small mammals  Most mammals are small  Insectovores (including shrews, moles, hedgehogs)  Rodents (largest are beavers and capybaras)  Rabbits  Bats – modification of the hand to wing and flight Carnivorous Mammals  Predators and meat eaters (some omnivorous)  Most have pointed, specialized teeth – carnassials  Uncommon as fossils because uncommon in life – represent 5% of warm-blooded population  Many are solitary animals (not all)5/19/2011 8 Diversification of Carnivores  Began with creodonts and miacids; creodonts extinct in Miocene  Similarity of dogs and hyenas = convergent evolution  Saber-tooth cats repeatedly evolved through the Cenozoic  Aquatic carnivores related to bears  See p 384 fig 18.135/19/2011 9 Ungulates or Hoofed Mammals  Artiodactyla – Even number of toes – Distinctive teeth – Cattle, goats, sheep, swine, antelope, deer, Hippopotomi  Perissodactyla – Odd number of toes – Distinctive teeth – Horses, rhinoceroses, tapirs, many fossil examples5/19/2011 105/19/2011 11 Elephants  Proboscidea –long snout  Widespread in Cenozoic; now only two species – Indian and African  Eocene Moeritherium probably semi-aquatic  Oligocene trend toward large size, trunk and tusks  Mastodons and Mammoths of Pliocene & Pleistocene – all of Northern Hemisphere Giant Aquatic Mammals – Whales  Cetacea – includes whales, dolphins, porpoises  Had land dwelling ancestors: artiodactyls? Carnivores?  Recent finds are bridging gaps in the record and show the transition from land to marine5/19/2011 12 Miocene Mammals Relatives of elephants, chalcothere, oreodonts, small camels, bear dogs, Saber-toothed cat, cranes5/19/2011 13 Pliocene Mammals Mastodon, rhinoceros, Cranioceras rodent, rabbit, Pronghorn, Sythetoceras, Pliohippus Pleistocene Faunas  Trend toward large body size – all over the world – Adaptation to cooler conditions of ice ages? – Large animals retain body heat longer  Excellent assemblages in Florida and Los Angeles (La Brea pits) – La Brea with inordinate number of carnivores. Why?5/19/2011 14 Large Pleistocene Faunas Sloths and armored glyptodonts of Florida5/19/2011 15 Rancho La Brea, LA county Natural History Museum Pleistocene Extinctions  What caused the extinctions?  Why in Australia and the Americas?  Why mainly the large mammals?  Hypotheses – Climate change – Human decimation5/19/2011 16 Intercontinental Migrations  Land bridges common in Northern Hemisphere  South American-North American connection in the Pliocene – The Great interchange – 50% of S. American are placental; 20% of N. American came from S. America  Australia still the home of the marsupials Primate and Human Evolution  Human ancestors may go back as much as 7 million years  Not a straight line – branches that became extinct  What are Primates? – Characteristics related to being arboreal  Skeleton, mode of locomotion  Increased brain size  Smaller, fewer, less specialized teeth  Stereoscopic vision  Opposable thumb – Prosimians and Anthropoids5/19/2011 17 Primate and Human Evolution  Prosimians – lower primates – Lemurs, lorises, tarsiers, tree shrews – Record from Paleocene – first primates – Small, 5 digits, clawed hands and feet, forwardly directed eyes with night vision – nocturnal – Eocene – abundant, retreated when cooler climate of the rest of Cenozoic – Moved southward to Asia, Africa, Southeast Asia, Madagascar5/19/2011 18 Primate and Human Evolution  Anthropoids – Evolved from prosimian lineage in Late Eocene – Old World Monkeys-Cercopithecoidea 