Introduction 1 Paleogene period within the Cenozoic Era is further divided into epochs a Paleocene 65 5 56 Ma i Based on plant fossils b Eocene 56 34 Ma c Oligocene 34 23 Ma i Based on fossils i Based on London Paris basin rocks 2 Cretaceous extinctions a Dinosaurs b Ammonoids c Rudists d Marine reptiles a Mollusks b Teleost fish c Flowering plants d Mammals 3 Paleogene survivors much more familiar to us 4 Earth s south polar region became glaciated Antarctic ice sheet formed at the Eocene Oligocene boundary marking the start of the glacial period in which we are living Paleogene Life 1 Marine life that durvived and recovered the Cretaceous ME defined the new normal modern like assemblages a Survivors i Benthic forams ii Plantonic forams iii Calcarerous nannoplankton iv Diatoms and dinoflagellates v Reef builders vi Sea urchin vii Cheilostomes bryozoans viii Crabs ix Snails x Bivalves teleost fish b New 2 New animals i Sand dollars burrowing sea urchins ii Borrowing bivalves a Whales Eocene evolved from carnivorous land mammals i Successful as large marine predators ii Basilosaurus lived in a sea once covering present day b Carcharodon sharks replaced the mososaurs as the dominant marine Louisiana predators 3 Flowering plants finally rise to dominance a Land plants didn t experience major evolutionary changes in the b But flowering plants expanded c Angiosperms dominate ferns and gymnosperms decrease in Paleogene abundance a Most modern orders were present by the Eocene 10 Ma after end of 4 Mammals radiated dramatically Creetaceous b Age of Mammals 5 2 general facts about mammals a Paleocene mammals were small b Eocene mammals had diversified greatly to include i Large whales ii Flying bats iii Tree climbing primates iv Elephants and horses v vi Ungulates vii Marsupials viii Monotremes Insectivores 6 The primate order to which humans belong evolved in the Paleogene period a Early primates like Cantius already had grasping ability both in the hind and forelimbs b Features are ancestral to hands and feet c Arboreal mammals used these grasping limbs to climb by the early Eocene 7 Ungulates lower foot c Two types a Mammals with hooves b Hooves are the enclosed nail or claw material covering the toes or i Odd toed expanded first horses tapirs rhinos ii Even toed or cloven hoofed expanded later goats sheep pig cattle bison camels d First horses Paleocene e Elephants Eocene 8 Early Paleogene birds were very large a Diatrymas predatory bird 2 4 m tall b Disappeared in late Eocene c Flying birds large shorebirds ducks i Webbed feet lived in colonies 9 Modern groups of large hoofed animals carnivores and primate expanded in the Oligocene as other early Eocene families died out a Largest land mammal of all time Paraceratherium an odd toed ungulate rhino 5 5 m 18 ft tall at the shoulder b Tapir sheep like animals hyena like animals saber toothed cats pigs and camels dominating by Oligocene 10 Modern carnivores became very abundant in the Oligocene a Order carnivore modern mammalian carnivores i Saber tooth tiger bear like dogs wolf like animals b Modernized primates appeared late Paleocene i Monkeys ape like primates 11 Frogs and insects were modernized in Paleogene 12 Reptiles and amphibians were relatively inconspicuous Eocene first record of Ranidae largest family of living frogs 13 Oligocene insects preserved in amber fossilized tree resin Paleogene Climate 1 The Eocene epoch began with a pulse of global warming a Onset of warmer climates is manifest as an abrupt shift in O isotope ratios towards smaller d18O values in planktonic and benthic forams Indicative of a rapid T increase b c No major ice volume to melt at that time i Thus isotope shift wasn t from global ice melting d Reduction in thermohaline circulation poorly oxygenated deep ocean e 70 of deep sea forams went extinct f C isotope ratios shifted to low levels extremely light C i Shells of deep sea forams and plant fossil tissues ii C in atmosphere and ocean were highly enriched with 12C g What caused this isotopically i Sudden melting of frozen methane hydrates extremely light ii Due to major slumping aling continental slopes iii May have caused rapid global warming iv Frozen methane release is only mechanism known to be so 2 Warmth in early Eocene extended to high latitudes powerful to explain large and abrupt shift a Fossil plants reveal tropical jungles covered many areas now in relatively cool climates 3 The Great Eocene Migratation climate warmth reflected in a large shift in a Land bridge between Siberia and Alaska b Today flooded the Bering Strait c Eocene primates ungulates and opossum make 1st appearance in NA 4 Warmth in early Eocene followed by Oligocene climatic cooling and flora fauna glaciation 5 34 Ma ME marked the Eocene Oligocene transition E O boundary a This is the modern glacial age when glaciers expanded over Antarctica b These glaciers have never since completely melted 6 Data from angiosperms strong correlation between mean annual T and the of plant species with smooth margins a Smooth higher T Jagged lower T b 7 Data from d18O shifting to larger values for shells of forams in deep sea indicate that the deep sea T were decreasing at the E P transition a Dense cold polar water sinking 8 What caused the ice sheet to develop at 34 Ma a A big drop in CO2 occurred at 32 Ma 2 Ma after the ice sheet buildup on Antarctica b Evidence from alkenones compound made by nannoplankton indicates high atm CO2 levels in Eocene as compared to early Oligocene c Rapid drop in Co2 indicates that a major global cooling occurred d But Antarctic ice sheets grew before 32 Ma e Glaciation began in the early Oligocene due to Australia rifting away from Antarctica f This permitted a large ocean current to encircle Antarctica g Physical isolation created a very cold circumpolar current 9 Why didn t the ice sheet expansion occur earlier a Although Antarctica was at the S Pole since the Cretaceous b Coasts were bathed by warm currents from equatorial regions c Separation from Australia allowed for the circumpolar current to develop d Reduced warm currents allowed for surface water cooling e Cold sinking water then filled the deep ocean with cold water Ice sheets spread quickly as the Antarctic climate cooled f 10 Moist tropical forests of the Eocene were replaced with dry woodlands and large grassy clearings in the cooler drier Ologocene a This lessened the amount of atm water vapor greenhouse gas b Newly de forested lands absorbed