BIOL 117 Lecture Notes - Lecture 28: Phanerozoic, Precambrian, Paleozoic
Document Summary
A fossil is the physical trace left behind by an organism that lived in the past: any indicator of past life, provides direct evidence about past life. The fossil record is the entire collection of fossils that we have available to us throughout the world. Most of the time dna can"t be found in fossils, because the biological material has been replaced with minerals, so the form of the organism remains but not the organism itself most of the times. Fossilization only occurs under ideal conditions and are comparatively rare: ~1 out of 200,000,000 individuals undergo fossilization. As new rocks form, older ones may be destroyed: abundance bias: organisms that are abundant, widespread, and present on earth for a long time leave evidence much more often than do species that are rare, local, or ephemeral. From the bones of a vertebrate, it is possible to reconstruct the way the muscles and blood vessels were attached.
