Natural Science Forum / Biology / Paleontology / April 2008

Wrong. "Fossilized" merely means "preserved". Some fossils are
relatively unaltered from their original condition. Others contain none
of the original material. There's no reason a fossil can't contain DNA.

M:

My short answer would be "no". First, "coprolite" is an applicable and
inclusive word here.

But a longer answer depends what you mean by "fossil". In general, things
younger than about
10,000 years (Holocene epoch) are often termed "sub-fossil". By this
definitional test,
your coprolite is a fossil.

Please note that some forms---under the right conditions of
preservation--may be mineralized within the arbitrarily
indicated sub-fossil period. The decapod crustacean Thalassina from the
richly mineralized
waters of the mangrove swamps in Australia are a nice example of younger
material
which attains a hard preservation quite quickly.

As to the DNA issue, I am sure it was extracted. In fact, DNA from various
other
animals which may have perhaps visited the cave to urinate was also found in
these
analyses. What condition, what completeness the examined DNA reflected is
another
question given the degradation one would expect it to undergo with time.
Nonetheless,
it would follow that the DNA obtained was significant enough to
make isolated species differentiations with assurance.

Regards,

Edward Hennessey