Biology 1001A Lecture Notes - Lecture 18: Stromatolite, Agnatha, Archaea
24 Nov 2017
School
Department
Course
Document Summary
Lecture 18 notes: how the relative position of fossils in sedimentary rock strata (higher vs lower) reveals their relative age. Oldest on the bottom layers: ways in which fossils can form. When dissolved minerals entered the spaces within the bones and then solidified. Animal fossils could contain footprints(when an animal walks across mud) Human fossils may have been frozen or mummified: reasons why the fossil record is incomplete. The fossil record is incomplete because few organisms fossilize completely, because some organisms are more likely to fossilize than others, and because natural processes destroy many fossils: importance of animal skeletons to the fossil record. Stromatolites are first living things the first fossil evidence of life, date to about 3. 5 billion years ago (bya). The earliest unicellular eukaryotes date from just over 2 bya, 1. 2 million species of eukaryotes (prokaryotes not involved) Difficult to tell if bacteria belong to the same species. Luca- most recent common ancestor of all living organisms.
