BILD 3 Lecture Notes - Lecture 14: Evolutionary Arms Race, Mesozoic, Cambrian Explosion
13 Jun 2018
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BILD 3 Lecture 14
5/4/2018
• All large Precambrian animals are soft bodied (Ediacaran period)
o There was little evidence of predation
• Cambrian explosion occurred because of the evolutionary arms race
o Massive diversification of animals
o Eat or e eate
o Diversification resulted in predators and defensive prey→trace taxa back to here
• Paleozoic: Ordovician
o Everything is still in the water
o Important events:
▪ Diverse marine invertebrates
▪ First cephalopods appear for the first time
▪ Early vertebrates (fish) started to diversify
▪ Possibly the start of colonization of land by plants (via spores)
• Paleozoic: Silurian
o Important event: multicellular life makes it onto land
o Transitional form between non-vascular and vascular
o What are plants to animals? Food!
• Paleozoic: Devonian
o When the land becomes colonized by animals
o First terrestrial arthropods (early)
o First tetrapods (late)
▪ Tiktaalik
• Paleozoic: Carboniferous
o Further diversification of plants on land
o Abundance of giant tree ferns, horsetails→vascular, seedless plants
o Amniotic eggs allowed for further exploitation of land by animals
▪ Most animals still lived at the edge of water before this because they
needed the water for protection of their babies
• Paleozoic: Permian
o Paleozoic Era ended with mass extinction due to volcanic activity and methane
release
o The Great Dig lasted aout 60,000 ears
• Mesozoic Era
o Three periods: Triassic, Jurassic, Cretaceous
o Begins with drifting apart of Pangea
o Age of the Diosaurs
• Triassic
o Early: no dinosaurs, lots of amphibians and some reptiles
o Late: first true mammals, marine reptiles, early dinosaurs
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