BIOA01H3 Lecture Notes - Lecture 7: Radiometric Dating, Centrosome, Cyanobacteria

• School: UTSC
• Department: Biological Sciences
• Course: BIOA01H3
• Professor: Mark Fitzpatrick

Document Summary

Fossil record: the problem is that it is incomplete, and that not all soft body organisms fossilize. As well, there is the issue of actual nding the fossils. The age of fossils can be determined by geological and radiometric dating. The earliest form of life, 3. 4 b years ago, is the cyanobacteria (blue algae)that actually produces the most oxygen in the world. The evolution of horses can be describes by marsh"s reconstruction. The number of toes, grinding surface of molar teeth, and the general size has drastically changed over time. Yet, the change is not linear, it is more of a branching pattern. So at one point in time, 3 types of horses were present and then at other points, for example at the very beginning, there was only one type of horse that existed. If organisms have ancestry, then we should be able to see the relations if traced back.