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NC State Paleontologist Discovers Soft Tissue in Dinosaur
RELEASE UNTIL 2 P.M. ON THURSDAY, MARCH 24
vessels found in bone matrix
of T. rex (A)
and ostrich (B).
wisdom among paleontologists states that when dinosaurs
died and became fossilized, soft tissues
didn’t preserve – the bones were essentially
transformed into “rocks” through a gradual
replacement of all organic material by minerals. New
research by a North Carolina State University paleontologist,
however, could literally turn that theory inside out.
Schweitzer, assistant professor of paleontology with
a joint appointment at the N.C. Museum of Natural
Sciences, has succeeded in isolating soft tissue from
the femur of a 68-million-year-old dinosaur. Not only
is the tissue largely intact, it’s still transparent
and pliable, and microscopic interior structures resembling
blood vessels and even cells are still present.
In a paper published in the March 25 edition of the journal Science, Schweitzer
describes the process by which she and her technician, Jennifer Wittmeyer,
isolated soft organic tissue from the leg bone of a 68-million-year-old Tyrannosaurus
was interested in studying the microstructure and
organic components of a dinosaur’s bone.
All bone is made up of a combination of protein (and
other organic molecules) and minerals. In modern bone,
removing the minerals leaves supple, soft organic materials
that are much easier to work with in a lab. In contrast,
fossilized bone is believed to be completely mineralized,
meaning no organics are present. Attempting to dissolve
the minerals from a piece of fossilized bone, so the
theory goes, would merely dissolve the entire fossil.
But the team was surprised by what actually happened
when they removed the minerals from the T. rex femur
fragment. The removal process left behind stretchy
bone matrix material that, when examined microscopically,
seemed to show blood vessels, osteocytes, or bone building
cells, and other recognizable organic features.
Since current data indicates that living birds are
more closely related to dinosaurs than any other
group, Schweitzer compared the findings from the
T. rex with structures found in modern-day ostriches.
In both samples, transparent branching blood vessels
were present, and many of the small microstructures
present in the T. rex sample displayed the same appearance
as the blood and bone cells from the ostrich sample.
Schweitzer then duplicated her findings with at least
three other well-preserved dinosaur specimens, one
80-million-year-old hadrosaur and two 65-million-year-old
tyrannosaurs. All of these specimens preserved vessels,
cell-like structures, or flexible matrix that resembled
bone collagen from modern specimens.
theories about fossil preservation hold that organic
molecules should not preserve beyond 100,000
years. Schweitzer hopes that further research will
reveal exactly what the soft structures isolated from
these bones are made of. Do they consist of the original
cells, and if so, do the cells still contain genetic
information? Her early studies of the material suggest
that at least some fragments of the dinosaurs’ original
molecular material may still be present.
“We may not really know as much about how fossils
are preserved as we think,” says Schweitzer. “Our
preliminary research shows that antibodies that recognize
collagen react to chemical extracts of this fossil
bone. If further studies confirm this, we may have
the potential to learn more not only about the dinosaurs
themselves, but also about how and why they were preserved
in the first place.”
The research was funded by NC State, the N.C. Museum
of Natural Sciences and the National Science Foundation.
- peake -
to editors: An
abstract of the paper follows.
Vessels and Cellular Preservation in Tyrannosaurus
Authors: Mary H. Schweitzer and Jennifer L. Wittmeyer,
North Carolina State University; John R. Horner, Montana
State University; Jan B. Toporski, Carnegie Institution
of Washington Geophysical Laboratory
Published: March 25, 2005, in Science
Abstract: Soft tissues are preserved within hindlimb
elements of Tyrannosaurus rex (Museum of the Rockies
specimen 1125). Removal of the mineral phase reveals
transparent, flexible, hollow blood vessels containing
small round microstructures that can be expressed from
the vessels into solution. Some regions of the demineralized
bone matrix are highly fibrous, and the matrix possesses
elasticity and resilience. Three populations of microstructures
have cell-like morphology. Thus, some dinosaurian soft
tissues may retain some of their original flexibility,
elasticity and resilience.