Evolutionary History (2):
- In the late 1970s, Dr. Carl Woese used RNA sequences to determine the relatedness of microbes
- He discovered that the prokaryotes can be divided into the vastly different groups of Bacteria and Archaea
- Methanogens were the first group of archaeans to be distinguished as completely separate from the Bacteria and Eukarya
- Since the discovery that the methanogens belong to the group Archaea, many other archaeal groups have been found
- Archaeal cells resemble the cells of bacteria but in many important ways are more like the cells of Eukaryotes
Fossil History (2):
- Molecular fossils of archaea (in the form of isoprenoid residues) were first reported from the Messel oil shale of Germany
- Chemical sediments of archaeans have been found in sediments from the Isua district of West Greenland (the oldest on Earth; they are about 3.8 billion years old)
- This tells us that archaea appeared on the Earth within one billion years of the planet's formation
