Introduction 1 Neogene period consists of a Miocene 23 5 3 Ma b Pliocene 5 3 1 8 Ma c Pleistocene 1 8 0 1 Ma d Quaternary is the last 2 5 Ma so Pleistocene straddles both the Neogene and Quaternary Neogene Global Events 2 Marine a Whales radiated i Sperm whales carnivores ii Baleen whales strain zooplankton iii Dolphins specialized whales b Planktonic forams recovered and expanded from the E O boundary ME 3 Terrestrial a Evolution of more land mammals i Even toed ungulates ii Bovidae cattle antelope deer iii Giraffes and pigs b Elephants i Miocene declined in Pliocene c Carnivorous mammals assumed modern character i Dog and cat families evolved ii Bear and hyena important to open terrain biota d New world primates appeared 4 On land explosion of grasses and herbs cascading radiation of animals a Grasses radiated to 10 000 species by end of Neogene b Herbs and weeds also radiated c Grass expansions were followed by a semi cascading expansion of mice songbirds and snakes forming a foodweb 5 The middle Miocene shift widening of the Southern ocean caused further thermal isolation of Antarctica 6 Continental scale glaciation followed 7 Global scale cooling lead to the expansion of glatiation on land masses surrounding the Arctic Ocean in the N Hemisphere in the late Pliocene 8 Global cooling and Antarctic Ice Sheet expansion are noted from O isotope records as the famous Middle Miocene Shift 9 Changes in ocean circulation triggered NHG 2 5 Ma late Pliocene a The N Hemi was warmer during the early Pliocene due to the open Isthmus of Panama i Water in the Atlantic gyre was well mixed with the Pacific b Thus the relatively fresh warm surface waters were transported northward by the Gulf Stream all the way to the Arctic Ocean i This kept the Arctic region warm c Since the late Pliocene to present the Isthmus of Panama has been i Water mixing between the Atlantic and Pacific ceased ii Atlantic surface currents became more salty and dense d The Gulf Stream now transported warm saline waters to the Arctic closed Ocean e Water moved northward evaporated and cooled more dense i Sank before reaching the Arctic Ocean f Thus the Arctic region cooled and allowed for glaciation Modern Ice Age of N Hemisphere modern ice age 3 2Ma 1 Following the early Pliocene warmth the N Hemi NH plunged into the 2 Climates in many regions have been cooler and drier ever since despite fluctuations in the extent of continental glaciers 3 Glacial maximum full glacial expansion 4 Glacial minima warmer intervals of glacial recession a Greenland ice cap is the only continental glacier to survive in NH 5 The frequency of glacial cycles predicted from orbital theory is consistent with the frequency of d18O cycles measured from forams a Thus the frequency of glacial cycles is controlled by solar radiation i Precession wobble of Earth s axis 20 000 year periodicity ii Obliquity variations in tilt of axis 41 000 year periodicity iii Eccentricity variations in the orbit from elliptical to circular 100 000 year periodicity 6 The last major expansion of ice in the Arctic occurred 18 Ka a Several lines of evidence to indicate the NHG was extensive and thick during the LGM b LGM was followed by rapid deglaciation 18 6 Ka 7 Evidence a Erratic boulders in Central Park in NYC b Linear patterns of glacial moraines debris band formed at the margin of LGM ice sheet i Complex pattern of moraines were formed by the advance and retreat of continental ice near the US Canadian border c Release of Lake Missoula water 12Ka formed the Channel Scablands d This is the largest flood ever identified on Earth e The top of the Columbia River Flood Basalts 17 15 5 Ma have unusually large scale erosional and depositional features too large to have been from the Columbia Rover evidence of a catastrophically massive release of water from Lake Missoula f The bare upper eroded surface of the Columbia Basalt has been g stripped of the overlying sed and soils In other locations large scale depositional dunes overlying the Columbia Basalt formed by the large volume water discharge h Isostatic depression rebound of the land from loading unloading by thick ice sheets that existed during the LGM i Zone of max ice cover LGM ii Land surface is still rebounding from the removal of weight from ice melting i Glacial scouring creating smooth rock surfaces i Smooth lower portions of mtns in NE US and N Rockies were polished by ice flow ii Rugged ice free tops were not polished as they weren t covered by flowing ice iii U shaped valleys mark zones of scour j Lowering of SL due to large ice volumes during the LGM i 120m SL drop ii Continental shelves were exposed globally and incised by iii An exposed land bridge also existed during this time at the Bering Straight during several Neogene glacial periods k Migration of plant and animal species as ice sheets expanded and rivers contracted i Pollen grains from buried soil layers help reconstruct vegetation changes that occurred in the previous glacial min like today ii Data conform vegetation zones and animals that ate these plants were shifted southward during LGM then migrated N as the ice retreated 8 Global distribution of vegetation changed from interglacials to glacial a Total shifts in vegetation belts with climate change b During glacials all latitudes cooled i N and S tundra expanded towards equator ii Tropical rain forests shrank and became isolated iii Deserts and semi arid grasslands expanded iv Grasslands and savannahs expanded Evolution of Homo sapiens 1 Miocene Age of Apes 2 Early apes radiated in Africa and Asia 20 Ma a These early apes are extinct b The fossil record for primates is poor and evolutionary connections are still poorly understood c However apes spread to Eurasia 15 Ma d This was followed by evolutionary radiations i Ground dwelling and arboreal e Of the early apes only the Gigantopithecus genus survived into the early Pliocene 5 23 Ma f During the decline of early apes the earliest known genus of the Hominid Family Sahelanthropus emerged from some unknown group of eary apes perhaps Gig 3 First hominid Sahlanthropus lived 7 6 Ma 4 Skull discovered in N Africa is neither early ape nor human a Intermediate morphology i Ape like brow ii Ape like brain case size iii Human like short relatively flat face iv Human like teeth 5 2nd hominid Ardipithicus 4 4 5 8 Ma a Found in Ethiopia 6 Australopithecus 3rd hominid genus evolving from Ard a 4 Ma found in Africa b Austr Is a genus name i Like Sah And