CENOZOIC- MAJOR EVENTS

•       Mammals rapidly diversify

•       Decline of reptiles

•       Diversification of

  –    Angiosperms - grasses

  –    Insects

  –    Birds

  

  

  

                                       Quaternary extinctions

•      Occur 10,000 years ago

•      End of Pleistocene

•      Small % killed

•      High % of megafauna killed

•      Highest % in Australia & Americas

                                       Quaternary extinctions

•      Climate change?

•      Overkill?

•      Disease?

•      Yet to be resolved













                               Opening of the Norwegian Greenland Sea

                                      Cenozoic Plate Tectonics

•       By Eocene time- the Americas had completely separated, Australia had started to separate
from Antarctica but India had not yet collided with Eurasia.  South America and Antarctica are still
attached.

                                      Cenozoic Plate Tectonics

•       During Miocene time - the Atlantic Ocean basin continued to widen and India had collided
with Eurasia

     The circum-Antarctic seaway was now open and the Antarctic Ice Sheet fully developed

                                         The Alpine orogen

•      Northward migration of Africa and Arabia closed the Tethys Sea

  –    Floor of the Tethys crumpled into emerging mountains

  –    Intense folding and faulting (Eocene-Miocene)

•      Formed the modern Mediterranean Sea

                                       Orogens of the Neogene



















                                     Cause of Messinian crisis:

•      20 Ma

  l  Arabian plate impinged upon Eurasion plate blocking connection between Mediterranean and Indian
  ocean

  l  Mediterranean totally landlocked with exception of small connection to Atlantic

  l  Connection closed periodically as Africa moved closer to Europe

  l  Led to drier climatic conditions in entire region



                                              Review:

•      5.5 Ma:  Repeat dessication and flooding



•      1.5 km:  Average depth of salt deposit

                    (3 km max)



•      4.8 Ma:  Seawater refills basin



•      Caused: Combination of tectonic activity                 and glacial/interglacial periods

                           Changes in Global Climate during the Cenozoic





















                                          Mammal Diversity



                                               Eocene

•      Bats first evolve







•      Elephants

  –    Moerithium

    •    Earlist

    •    Pig sized









                                               Eocene

                                          Quaternary life

•      Familiar animals

•      Geographic distribution is different

  –   Camels, rhinos in N. America

•      Mega fauna!!















                                  Major Events in Human Evolution

•      Evolution of Hominidae



•      Habitation of diverse environments



•      Gracile vs. robust hominids

                      Evolution of Family Hominidae within the Order Primates

•      Usually defined by the evolution of bipedal locomotion



•      Oldest indisputably bipedal hominids are 4.3 Ma (Australopithcus anamensis), but may have
evolved by 6 Ma (Orrorin tugenensis)

                              Habitation of more diverse environments

•      First hominids lived in gallery forests along streams and rivers



•      Later hominids moved into more open territory (savanna grasslands) that developed in the
Miocene-Pliocene





                                   Recent View of Human Evolution