Lecture on the Cenozoic Era

Timeline and Overview

• Geologic Eras Recap:
  • Pre-Cambrian: Haitian, Archaean, Proterozoic
  • Paleozoic Era
  • Mesozoic Era
  • Cenozoic Era (current era)
• Key Event: Humans

Major Geological Events in the Cenozoic

• Paleogeography:

  • Finalization of continental configurations
  • Major continental movements: India colliding with Asia, Australia and Antarctica separation

• Current Configuration:

  • Tectonic features: Himalayas, Alps, Andes, San Andreas Fault, Grand Canyon, North American Rocky Mountains

• Tectonics and Mountain Building:

  • Courtyard Mobile Belt:
    • Laramide Orogeny: Subduction of Farallon Plate leading to compressional stress
    • End of subduction and beginning of shear stress: Formation of San Andreas Fault
    • Basin and Range Deformation: Transition to extensional stress, formation of normal faults, horsts, and grabens
  • Rifting:
    • Rio Grande Rift (5-10 million years ago)
    • Rifting between Baja California and Mexico: Gulf of California formation

• Global Orogenies:

  • Himalayan Orogeny: India colliding with Asia
  • Alpine Orogeny: Africa colliding with Europe, formation of Mediterranean, Black, and Caspian Seas
  • Andean Orogeny: Subduction of Nazca Plate under South America
  • Ring of Fire: Defined by earthquakes and volcanic activity along Pacific Ocean margins

• Geological Timeline Summary:

  • Paleocene: Andean Orogeny, formation of Ring of Fire
  • Eocene: Himalayan and Alpine Orogenies, end of Laramide Orogeny, formation of San Andreas Fault, Basin and Range extension
  • Pleistocene: Ice age
  • Present: Continuation of Himalayan, Alpine, Andean, and Basin Range activities

Climate in the Cenozoic

• Paleocene-Eocene Thermal Maximum: Hot period around 55 million years ago
• Cooling Trend: Associated with continental fragmentation
• Pleistocene Ice Age: 2.6 million years ago, followed by warming

Biological Events and Evolution

• Age of Mammals (Vertebrates) and Insects (Invertebrates)

• Marine Invertebrates:

  • Evolution of modern bivalves
  • Gastropods expanding to various environments
  • Scleractinian corals dominating reef building
  • Dominance of diatoms, dinoflagellates, and foraminifera
  • Diversification of echinoids
  • Marine arthropods: Lobsters, shrimp, trace fossils of annelid worms

• Terrestrial Invertebrates:

  • Dominance of insects and arachnids

• Marine Vertebrates:

  • Predominance of bony fish
  • Evolution of Carcharodon megalodon in the Eocene
  • Survival and evolution of sea turtles and sea snakes
  • Cetacean evolution: Whales in the Eocene, dolphins in the Miocene

• Terrestrial Vertebrates:

  • Mammals: Major diversification by the Eocene
    • Marsupials and Monotremes: Dominance in Australia, migration due to the Panamanian land bridge
    • Primates: Evolution of old and new world monkeys, common ancestors with humans
    • Ungulates: Evolution of hooved herbivores
    • Carnivores: Evolution of small to medium-sized hunters, megafauna in the Pleistocene

Plant Evolution

• Angiosperms: Dominance of flowering plants
• Grasses: Expansion in the Miocene, rise in grazing animals

Paleontological Summary

• Evolution of first primates, ungulates, large flightless birds, cetaceans, old and new world monkeys, large sharks, songbirds, grasses, grazing ungulates, first hominins, and megafauna
• Sixth Mass Extinction: Current state, ongoing research

Conclusion

• Summary of key geologic and biological events in the Cenozoic
• Mention of the potential sixth mass extinction