Fossil

A fossil is a preserved remain, trace, or impression of an organism from the geological past. Fossils record ancient life and the environments in which organisms lived.

Permineralization: A fossilization process in which minerals fill pores in buried biological material. Minerals entering bone or wood pores can preserve internal structure.
Sedimentary rock: Rock formed from sediment deposited, compacted, or chemically precipitated at Earth's surface. Most fossils occur in sedimentary rock, where remains can be buried and preserved.
Biostratigraphy: The use of fossil distributions to identify and correlate the ages of rock layers. Distinct fossil assemblages let geologists match strata across distant locations.
Burgess Shale: A Canadian fossil deposit famous for exceptionally preserved animals from the Cambrian Period. Its soft-bodied fossils reveal anatomical diversity rarely preserved in ordinary deposits.
Sampling bias: A systematic distortion caused when observed examples do not represent the full population or process. Fossil discoveries overrepresent organisms and places that preserve and expose remains.
Replacement (paleontology): A fossilization process in which minerals replace the original material of a buried remain. Replacement can preserve an organism's shape after its original substance disappears.
Geologic time scale: A system for organizing Earth's history into nested intervals based on rocks, fossils, and geological events. Fossils help define and correlate many divisions of geological time.
Index fossil: A fossil of a widespread, short-lived species used to identify and correlate rock layers. Its limited time range makes it useful for dating strata relatively.
La Brea Tar Pits: An asphalt deposit in Los Angeles that preserves abundant Ice Age fossils. Its fossils document late Pleistocene animals and their ecological associations.
Completeness of the fossil record: The degree to which fossils represent the organisms and communities that existed in the past. Uneven preservation makes absence of fossils difficult to interpret.

Linked from 156 pages