EESA06H3 Lecture Notes - Lecture 6: Subduction, Bivalvia, Anomalocaris
Document Summary
Step 2: the cambrian explosion: 542 ma (multicellular animals with shells, backbones etc) Step 3: diversification during the paleozoic: c. 400-250 ma. Hadean period hell on earth - rocks was molten, no water no atmosphere. Diversification heavier elements sank to the middle. Magnetic field to hold on to the gases which build up atmosphere + oceans. Shells buried and preserved unaltered (<100 million years) Mineralization - cavities are filled with silica, calcium carbonate, iron (ex: tree stumps) Most fossils are found in sedimentary rock: exception: pompeii people covered by pyroclastic flow and fossilized in ash. Sedimentation (fine grained =more detail, chemical makeup of rock = color) More sediments pile on = pressure rock. Mineral rich water = changes to the shell. Uplift by continental crusts coming together (plate tectonics) Ammonite fossils iridescent aragonite with trace elements (fe, mn, al, ba) Palaeocology study of ancient organisms and their environments: (st. cuthbert rings, sea lily - crinoide)
