K/T Extinction
zResults of impact-
yRelease of energy = many H-bombs
y Initial high temperature, then global cooling
y Ocean water vaporized to sea floor
zVolcanic eruption Hypothesis
yConcentration of Ir high in some volcanoes
y Dying may not have been very sudden
y Time of vast basalt eruptions in India
K/T Extinction
zNewer findings-
yImpact crater found in Iowa, but too small
y Giant wave deposits (?) found in Texas
y Big (110 miles) crater off coast of Yucatan found in 1990- the "smoking gun"
y Reassessment of dinosaur evidence
zImpact hypothesis now impact theory
yBut… there may have been other contributions to extinction

PLANTS
zFlowering Plants become dominant
z Grasses arose
yReplaced forest where climate became cooler and drier
IN SEAS
zModern fauna developed
z Enormous sharks in early Tertiary
z Whales
CENOZOIC
MAMMALS
zModern mammals appear quickly
yWhales, carnivores, primates, etc.

MAMMALS
zMajor groups isolated as Pangea brokeup
yMarsupials in Southern Continents
zGreat diversity- evolution into major groups
yCanines- including large wolves
y Cats- including large, saber-toothed cats
y Camels, Deer, Pigs, Bears, Elephants, Rodents, Primates (Monkeys, Apes, humans), Horses

MAMMALS
zMiddle Cenozoic Americas extinctions
yWhen S. America and N. America connected
zIce Age species- Large bodies
ywooly mammoth; saber-toothed cats, dire wolf, giant condors, giant sloths.
y Extinction of most large animals approximately 10,000 years ago at end of Pleistocene Ice Age

OTHER FAUNA
zBIRDS
yLarge variety, including penguins, flying birds, song birds, etc.
y Extinct large, flightless birds
zINSECTS
HUMANS
zPoor fossilizing environment
z Ancestor not modern ape, but an ancestor common to apes and humans
yFirst clear hominids- Australopithecus
x4.0 - 1.3 m.y. x from Africa
x Our most direct ancestor- A. Afarensis "Lucy"
•Body upright- pelvis, legs, feet like human• Skull is ape-like; small brain capacity
• Teeth intermediate between apes and people
HUMANS
zHomo - 1.6 m.y. to present - spread from Africa
yskull more human & larger braincase
y evidence of tool making
zH. Sapiens - modern humans
z H. Neanderthal - lived 100,000 - 35,000 y.a.
ymassive, short body
zH. Sapiens Sapiens - present humans
ycame to N. America by Bering land bridge
y at least 11,000 y.a. (sea level low in Pleistocene)