http://www.livescience.com/animalworld/060724_fossil_bonemarrow.html
* Pictures are availabe on the website.

Rare Discovery: Fossilized Bone Marrow is 10 Million Years Old

By Ker Than
LiveScience Staff Writer
posted: 24 July 2006
04:37 pm ET

Scientists have extracted intact bone marrow from the fossilized
remains of 10-million-year-old frogs and salamanders.

The finding, detailed in the August issue of the journal Geology, is
the first case of fossilized bone marrow ever to be discovered and
only the second report of fossilized soft tissue. In June of 2005,
scientists announced they had found preserved red blood cells from a
Tyrannosaurus rex leg bone.

"It pushes back the boundary for how far [soft tissue] fossilization
can go," said study leader Maria McNamara of University College
Dublin in Ireland.

Why it matters

Preserved soft tissue could provide insight into the physiology of
ancient beasts that can't be gleaned from their fossilized bones
alone. If scientists could find bone marrow from dinosaurs, for
example, it could help resolve the debate about whether the
creatures were warm-blooded or not, McNamara said.

Both the frog and salamander species are long extinct, but the
families to which they belonged still thrive today. The animals were
found in the Teruel province of Spain, a region that was once a deep
lake.

The researchers suspect that the bones of the amphibians formed
protective microenvironments that prevented bacteria from seeping in
and rotting the tissues.

Hopes raised

The discovery raises hopes for finding soft tissue in other regions
and from other animals, including mammals, McNamara says, because
the amphibian bone marrow was discovered in an environment vastly
different form the one in which the T. rex soft tissue was found.

It's also possible that already exhumed fossils contain soft tissue,
but that they've been missed because detection requires breaking the
bones apart.

"Any reasonable museum curator isn't going to let you go around
smashing up the bones in their collections," McNamara told
LiveScience.

The researchers are currently testing to see if DNA or other organic
molecules were also preserved.