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The Cenozoic Era
1.8
5.0
23.7
33.5
54.5
66.4
Ma
Major themes of the Cenozoic
• Earth– overall climatic cooling (“greenhouse to icehouse”)– changes in ocean circulation– Pangea breakup continues but slows– changes in position of land and sea– changes in oceanic nutrient levels
• Life– diversification and dominance of mammals– dominance of angiosperms– continuation of the Mesozoic Marine Revolution
The Earth in the Cenozoic
• Changes in position of land and sea– destruction of Tethys– effects on climate– effects on ocean circulation– land bridges
• Changes in ocean circulation– cooling more vigorous circulation– continental position new current patterns
• Overall climatic cooling– continental position S. Hemisph. glaciation
Glomar Challenger
JOIDES Resolution
The Deep Sea Drilling /Ocean Drilling Project(DSDP/ODP)
Oxygen isotope paleothermometry
• O isotope fractionation is temperature-dependent (warmer temps more 16O, less 18O)
• expressed as ppt relative to PDB (Pee Dee Belemnite)
• need to correct for ice volume (more glacial ice SW enriched in 18O)
Oxygen isotope paleothermometry
18O negative =warmer
18O positive =cooler
Major climate events of the Cenozoic
• Late Paleocene Thermal Maximum (LPTM)
• Eocene-Oligocene cooling / Antarctic glaciation
• Miocene cooling
• Pleistocene glaciation
The carbon isotopic excursion at the P-E boundary
Possible cause(s) for the LPTM
more hydrothermal activity
more CO2 warming release of
methane clathrates more CO2
warming
Methane Hydrates
Major climate events of the Cenozoic
• Late Paleocene Thermal Maximum (LPTM)
• Eocene-Oligocene cooling / Antarctic glaciation
• Miocene cooling
• Pleistocene glaciation
The breakup of Gondwanaland:the death of Tethys and the formation
of the Circumantarctic Current
• India collides with southern Asia (ca. 55 Ma)
• Australia separates from Antarctica (ca. 58 Ma)
• South America separates from Antarctica -- the Drake Passage (33.5-23.5 Ma)
Major climate events of the Cenozoic
• Late Paleocene Thermal Maximum (LPTM)
• Eocene-Oligocene cooling / Antarctic glaciation
• Miocene cooling
• Pleistocene glaciation
The rise of mammals
Eocene Miocene
The evolution of whales
http://www.indiana.edu/~ensiweb/images/whal.amb.jpeg
An artist's rendering of Rodhocetus. This mammal lived near the
shores of the Tethys Sea, between Asia and the South
Asian subcontinent, about 47 million years ago.
The real fossil bones of the walking and swimming whale, Ambulocetus natans, are spread out in this picture with a sledgehammer for scale. The skeleton was about 12 feet long and is about 49 million years old. It was found in Pakistan.
Basilosaurus, Eocene of Alabama
