[Astronomy 2021A/B] - Midterm Exam Guide - Everything you need to know! (14 pages long)

• School: Western University
• Department: Astronomy
• Course: Astronomy 2021A/B
• Professor: Alyssa Gilbert

Document Summary

The when, where, why, and how of the beginning of early life on earth. Must study this question through the study of fossils. The geological record is incomplete and therefore we have not yet discovered the oldest intact fossils. This means we do not know exactly how long life has existed on earth. These are rocks characterized by a distinctive layered structure. The similarity of structure between ancient stromatolites and the modern-day mats suggests a similar origin, which implies that they are fossil remnants of early life. These date back to 3. 5 billion years ago, which is the current suggested origin. But since these stromatolites operate on photosynthesis, which takes time to process, we could even argue that an even more primitive life form existed before this 3. 5 billion years ago. The second line of evidence comes from individual fossilized cells.