GEOL 107 Lecture Notes - Lecture 10: Ediacaran Biota, Sturtian Glaciation, Marinoan Glaciation

• School: Queen's University
• Department: Geological Sciences and Geological Engineering
• Course: GEOL 107
• Professor: Guy M Narbonne

Document Summary

Current techniques suggest that the first radial animals evolved ~650 ma and the first bilaterians evolved 575 ma. This is only slightly older than the fossil record so is plausible. First animals are linked to three episodes of neoproterozoic glaciation: sturtian glaciation (740 ma) sponge biomarkers, marinoan glaciation (635 ma) microscopic animals and empryos, gaskiers glaciation (580 ma) ediacara biota, worlds first large eukaryotes. Mistaken point, eastern newfoundland, contains the oldest known fossils (580. Ma: sudden increase in o2 in deep-oceans, making them closer to modern oceans, dominated by highly fractal forms, probably from an extinct clade. Fed by suspension feeding of particles or osmoptrophy (taking dissolved chemicals out of seawater) No evidence of bilaternal, mobile, or burrowing animals. Other ediacara biota (560-550 ma) have been found in australia, and russia: some extinct clades (ex. rangeomorphs, forms with bilateral symmetry (ex. Dickinsonia, kimberella, spriggina: worm burrows show shallow and undirected burrowing.