Geoscience Reference
In-Depth Information
5
Recording
palaeontological
information
Robert A. Spicer
5
5.1 Introduction: Fossils are smart particles
Unlike many sedimentary particles, such as quartz grains, each
fossil has a story to tell that goes beyond its composition and
the way in which it was transported and deposited. A body
fossil represents the remains of a once living organism that had
a life history, a certain environmental tolerance, and a defi ned
range in terms of its geographical and stratigraphic distribution.
Body fossils may be large, as in the case of a complete
mummifi ed mammoth, or microscopic, such as a pollen grain.
Trace fossils represent impressions that an organism made in
sediment, such as a footprint, or the disturbance of sediment as
the animal went about feeding, or burrowing to create a living
space. Fossils can also provide evidence of their decay process
(including post-mortem scavenger behaviour), burial and
tectonic history, all of which provide information on ancient
environments. Moreover fossils occur in assemblages that may
refl ect predominantly life communities or processes of
transport, deposition and decay that can also inform on past
environmental conditions. Fossils are 'smart particles'.
Fossils are smart particles so
they are worth noting in
detail. Not only do they yield
information about energy
levels and provenance like
other types of sedimentary
grain, they are also sensitive
to factors such as climatic
conditions, time and water
depth.
5.1.1 Why are fossils important?
The occurrence of fossils in most sedimentary rocks, and more
rarely in extrusive igneous rocks such as basalt lava fl ows and
ash deposits, can be used to obtain stratigraphic, environmental
and evolutionary information. Fossils can provide:
•
a wealth of information on ancient life forms and thus are
important in understanding the history of life on Earth and
our place within it;
•
data on ancient ecosystems and palaeoecology that have
relevance to managing our planet today and in the
future;
