GEOL 1020 Lecture Notes - Lecture 25: Bioturbation, Subduction, Grypania
7 Dec 2017
School
Department
Course
Professor
Document Summary
Proterozoic eon (chapter 12, page 278 - 291) About 88% of earth history occurred in the precambrian, before the. Today we will focus on the proterozoic eon. Modern style of tectonic marks the beginning of the proterozoic eon. Oldest undoubted mountain chain is proterozoic: wopmay orogen (~1. 9. Oldest eukaryotes appear ~2. 1 ga a eukaryote has a nucleus and membrane-bound organelles. The outsides of these fossils look as though they have been squished up or dehydrated. Look deformed, suggesting they did not have a hard shell. Earliest evidence of eukaryotes with biomineralized shells (or skeletons) is late proterozoic (~717 - 811 ma). These plate-like microfossils are made of ca phosphate, and may belong to green algae. Some single-celled eukaryotes that date to ~750 ma resemble modern amoebas with skeletons/shells. Neoproterozoic: late proterozoic (~900 - 542 ma) Ediacaran ( = vendian; latest proterozoic): 635 - 542 ma. The oldest, undoubted multicellular animals burst on the scene ~580 ma.
