A Tyrannosaurus rex fossil has yielded what appear to be the only preserved soft tissues ever recovered from a dinosaur. Taken from a 70-million-year-old thighbone, the structures look like the blood vessels, cells, and proteins involved in bone formation.
Most fossils preserve an organism's hard tissues, such as shell or bone. Finding preserved soft tissue is unheard of in a dinosaur-age specimen.
"To my knowledge, preservation to this extent—where you still have original flexibility and transparency—has not been noted in dinosaurs before, so we're pretty excited by the find," said Mary H. Schweitzer, a paleontologist at North Carolina State University in Raleigh.
The findings may provide new insights into dinosaur evolution, physiology, and biochemistry. They could also increase our understanding of extinct life and change how scientists think about the fossilization process.
"Finding these tissues in dinosaurs changes the way we think about fossilization, because our theories of how fossils are preserved don't allow for this [soft-tissue preservation]," Schweitzer said.
Uncovering T. Rex
For three years scientists from the Museum of the Rockies in Bozeman, Montana, excavated the T. rex from sandstone at the base of the nearby Hell Creek formation. The dinosaur was relatively small and around 18 years old when it died.
"The dinosaur was under an incredible amount of rock," said Jack Horner, a curator of paleontology at the museum. "When it was collected, the specimen was very far away from a road, and everything had to be done by helicopter.
"The team made a plaster jacket to get part of the fossil out, and it was too big for the helicopter to lift. And so we had to take the fossil apart.
"In so doing, we had to break a thighbone in two pieces. When we did that, it allowed [Schweitzer] to get samples out of the middle of the specimen. You don't see that in most excavations, because every effort is made to keep the fossil intact," said Horner, a co-author of the study.
A certain amount of serendipity lead to the discovery.
Because the leg bone was deliberately broken in the field, no preservatives were added. As a result, the soft tissues were not contaminated.
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