Fossils are the preserved remains or traces of organisms. Also fossils are evidence of past life and fossils are an evidence of evolution.
The fossil record: Show us organisms that have evolved in a historical sequence. The age is determined by Relative dating or Radiometric dating. But fossils records have problems the more important are that fossils form by chance, quality of fossils varies, fossils reconstruction requires thorough knowledge of anatomy and dating of fossils is achieved through various methods