EESA06H3 Lecture Notes - Lecture 6: Chordate, Proterozoic, Hypersaline Lake
Document Summary
Lecture 6 - the biological record: history of life on earth. A very short history of life on earth. Step 1 the earliest bacteria: 3. 8 ga (?) Step 2 the cambrian explosion: 542 ma (multicellular animals with shells, backbones etc. ) Step 3 diversification during the paleozoic: c. 400-250 ma. Shells buried and preserved unaltered (<100 million years) Cavities filled with silica, calcium carbonate, iron - a process called mineralization. Uplift and erosion: rock with fossils were uplifted and the layers were eroded so that is why you can see fossils at the level that we walk on. Ammonite fossils - iridescent aragonite with trace elements (fe, mn, al, ba) Palaeoecology - study of ancient organisms and their environments. Sea lilies - shallow water, crinoid (fancy name for sea lily), 6 feet tall, breaks up into rings. How do we use fossils in stratigraphy: to establish relative age of rock units, correlate units.
