Rare Discovery: Fossilized Bone Marrow is 10 Million Years Old

Intact bone marrow (B and C) was extracted from the fossilized remains of Rana pueyoi (A), a frog that lived 10-million years ago. (F) shows an electron micrograph close up of one of the samples. (Image credit: M.E. McNamara/Geology)

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.