Answer:
Cyanobacteria
Cyanobacteria: Fossil Record
The oldest known fossils, in fact, are cyanobacteria from Archaean rocks of western Australia, dated 3.5 billion years old. This may be somewhat surprising, since the oldest rocks are only a little older: 3.8 billion years old!
The age of the fossil must be determined so it can be compared to other fossil species from the same time period. Understanding the ages of related fossil species helps scientists piece together the evolutionary history of a group of organisms.
Explanation:
Source:ucmp.berkeley.edu
and courses.lumenlearning.com
