• The original predecessor involved in the origin of life is not known but it has been speculated that it might have had RNA as its genetic material (18)
• Arguments are convincing that bacteria have been around since early Precambrian time, about 3.5 billion years ago (18)
• Bacteria fossils in rocks have been discovered dating from at least the Devonian period (416-359.2 million years ago) (18)
• The oldest known bacteria in the fossil record are cyanobacteria; which are 3.5 billion years old.  The fossils may form large layered structures called stromatolites or oncolites (17)