1. Earth History, Ch. 181 Western U.S. orogenies

2. Earth History, Ch. 182 Late Cretaceous 75 Ma

3. Earth History, Ch. 183 K/T boundary 65 Ma

4. Earth History, Ch. 184 The Paleogene World Two-fold subdivision of Cenozoic: Paleogene, Neogene Previously, Cenozoic was divided into Tertiary (Paleocene-Pliocene) and Quaternary (Pleistocene- Holocene) Know periods and epochs! Cenozoic Paleogene Neogene Paleocene Eocene Oligocene Miocene Pliocene Holocene Pleistocene 65 24

5. Earth History, Ch. 185 Paleogene life In marine realm, most groups that survived end-Cretaceous mass extinction recovered and diversified during Paleogene –Planktonic forams, calcareous nannos, mollusks, arthropods Demise of giant marine reptiles opened the door to whales (Eocene) and giant sharks!

6. Earth History, Ch. 186 Whale evolution (Eocene-Holocene) Terrestrial ancestor Large, marine forms

7. Earth History, Ch. 187

8. 8 Giant Eocene shark Modern shark jaws

9. Earth History, Ch. 189 Paleogene life Other interesting newcomers to marine or marginal marine habitats: –Penguins –Pinnipeds (seals, sea lions, walruses)

10. Earth History, Ch. 1810 Paleogene life On land………….. –Diversification and “modernization” of angiosperms –By early Oligocene time, half of all angiosperm genera were ones that still exist today Origin of grasses –Earliest forms were sedge-like (discontinuous growth) –Late Oligocene-Neogene forms capable of continuous growth (able to withstand grazing pressure)

11. Earth History, Ch. 1811 Paleogene life Explosive adaptive radiation of mammals! –By Eocene time, most modern orders of mammals had appeared, including primates, carnivores and horses Cantius, climbing around in our family tree!

12. Earth History, Ch. 1812

13. Earth History, Ch. 1813

14. Earth History, Ch. 1814 Eocene fossil bat

15. Earth History, Ch. 1815 Hyracotherium (“Eohippus”) earliest horse Dog-sized 4 toes 3 toes

16. Earth History, Ch. 1816

17. Earth History, Ch. 1817 Diacodexis (early even-toed ungulate)

18. Earth History, Ch. 1818 Eocene elephants

19. Earth History, Ch. 1819 Diatryma (a top predator--stay away from this turkey!) 8 ft

20. Earth History, Ch. 1820

21. Earth History, Ch. 1821 Paleogene life Oligocene was noteworthy for: –Paraceratherium, largest land mammal ever (member of rhino family) –Origin of true monkeys –Expansion of big cats

22. Earth History, Ch. 1822 Paraceratherium 18 ft at shoulder

23. Earth History, Ch. 1823 Aegyptopithecus (Oligocene monkey)

24. Earth History, Ch. 1824 Dinictis (Oligocene saber-tooth cat)

25. Earth History, Ch. 1825 Oligocene mammalian fauna of Nebraska & South Dakota

26. Earth History, Ch. 1826 Paleogene life Many groups of mammals became extinct during Eocene time or at the Eocene— Oligocene boundary Climate change probably is responsible for extinctions

27. Earth History, Ch. 1827

28. Earth History, Ch. 1828 Paleogene paleogeography and climate Beginning in late Eocene, climate rapidly became cooler and drier –Relatively heavy oxygen isotope ratios (consistent with growth of continental glaciers) –Establishment of circum-polar currents around Antarctica

29. Earth History, Ch. 1829 Evidence for climate change

30. Earth History, Ch. 1830 Antarctic circumpolar current SA ANT AU

31. Earth History, Ch. 1831 Continued break-up of Pangaea