GEOL 102 Lecture Notes - Lecture 14: Lynn Margulis, Uraninite, Archean
Document Summary
The first organisms would have been prokaryotes. Prokaryotes are organisms whose genetic material is not contained in a cell nucleus. Prokaryotes are generally divided into two large groups. Fossils of many prokaryotes are difficult to identify in the absence of genetic data. While largely unicellular some prokaryotes can form into communal masses called biofilms. Fossils of layered biofilms are called stromatolites. Oldest stromatolites have been found in australia and are dated to 3. 45 bya. Very common fossils by the late archean persist in modern ecosystems. Possible that not all fossil examples were. Organisms with a cell nucleus containing their genetic material. Includes some unicellular organisms and all multicellular ones, including animals plants fungi. Many also have organelles- specialized subunits of cells. Some seem to represent remnants of early symbiotic relationships. Earliest eukaryote fossils are from the proterozoic eon 2. 1 bya. Multiple examples from roughly the same time most represent eukaryotic algae.
