paleontology sources 

sources:     Normal   0                         MicrosoftInternetExplorer4         from Prothero, Donald, 2004, Bringing Fossils to life,  McGraw Hill Higher Education, pp. 8-18.

Taphonomy

“The study of how living organisms become fossilized is known as taphonomy.  … From the moment an organism dies, there is a tremendous loss of information as it decays and is trampled, tumbled, and broken before it is buried.  The more of that lost information that we can reconstruct, the more reliable our scientific hypotheses are likely to be.  ….  From the original complete assemblage of living organism, known as a ‘life assemblage” or biocenosis, many events occur that screen out certain organisms, leaving a much smaller death assemblage, or thanatocenosis.  The process of breakup and decay of organism immediately after death is known as necrolysis. 

“After a death assemblage accumulates, many other factors operate on the hard parts to break them up and scatter them around, so an even smaller percentage ends up buried for future fossilization.  These processes occur after necrolysis and are known as biostratinomy.  These agents of destruction can be biological, mechanical, or chemical.

“Biological agents are the most important factor in most environments, both marine and terrestrial.  Both predators and scavengers are very active in breaking up shells and bones ….  In summary, the key factor that prevents biological destruction is rapid burial.”

For those organism that are not buried right away:

“Mechanical agents of destruction such as wind, waves, and currents can be very important.  These processes are most effective in shallow waters, where both waves and storm have their highest energies.  … In summary, the shape, density, and thickness of the bone or shell are the most important factors in determining survival under mechanical transport [until burial].”

“After burial a variety of digenetic [chemical] changes in the rock can easily destroy shells.  … In summary, the original composition and the groundwater chemistry are the most important factors in determining whether digenetic changes are likely to alter or dissolve a fossil.”

“Taphonomic research has come a long way since the pioneering studies of the 1960s and 1970s.  Paleontologists can no longer afford to naively take the fossil record at face value, but must always keep in mind the taphonomic “noise” that may obscure the original biological ‘signal’.”

Lagerstatten:

“The processes outlined above account for most fossilization and what we know of the living organism is usually quite incomplete.  However, there are extraordinary fossil deposits around the world that preserve soft tissues and sometimes even skin texture and color patterns. … These are known as Lagerstatten (German for “mother lode”), and they have produced some of the most important fossils known.  … From all these examples, several general trends emerge.  The best fossilization occurs when there is rapid burial and anoxic conditions to prevent scavenging, no reworking currents and little or no digenetic alteration to destroy the fossils.”

The Museum of the Rockies here in Bozeman is the realm of paleontologist Jack Horner.  I have often heard Jack speak, pointing out that the dinosaurs of Montana were almost all killed and buried by catastrophic river floods near the shore of the inland sea that is now Eastern Montana, the Dakotas and related Canadian States.  The bones and the geology both acclaim to that.  Of course, these floods are considered local in extant.  This same theme is echoed on many signs and posters through out the museum.