Biology 3484A/B Lecture Notes - Lecture 6: Dickinsonia, Agnatha, Coevolution
24 Mar 2018
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Island scrub jays on santa cruz island occupy two niches (pines and oaks) Species diversity: species diversity the result of gain (speciation) and loss (extinction) of species, this was a time of huge diversity mystery of how the fossils before this period came from. Cambrian fossils: a lot of fossils came from whales in this period, found in the 1830s, 30 years later came darwin (and he studied those fossils) Earth timeline: origin of earth first life arises (3. 8 billion years ago) multicellular life evolves (2. 1 billion year) Eukaryotes evolved (about 1. 6 billion years ago) homo sapiens (0. 2 million year ago: earth is 4. 6 million years old, gradual appearances of organisms and eukaryotes. This comes from a mix of evidence, including stable isotopes, genetic clocks, and (most recently) fossils. Earth"s ti(cid:373)eli(cid:374)e (cid:894)last 600 (cid:373)illio(cid:374) years ago(cid:895: ediacaran period 600 million years ago, cambrian period 500 million years ago, focus on those two periods specifically.
