Fossils
(from
Latin fossus, literally "having been dug
up") are the
mineralized or otherwise preserved remains or
traces (such as footprints) of animals, plants, and
other organisms. The totality of fossils, both
discovered and undiscovered, and their placement in
fossiliferous (fossil-containing)
rock formations and
sedimentary layers (strata)
is known as the fossil record. The study of
fossils across
geological time, how they were formed, and the
evolutionary relationships between
taxa (phylogeny)
are some of the most important functions of the
science of
paleontology.
The
relative geological time scale, as developed during
the 19th century, is based largely on the fossil
content of the rock strata. The development of
radiometric dating techniques in the early 20th
century allowed geologists to determine the
absolute age of the various strata and the
included fossils. Fossils range in age from the
relatively recent
Holocene epoch several thousands of years in age
to those of the
Archaean era several
billions of years old.
(Definition of
http://en.wikipedia.org/wiki/Fossil )