New
evidence adds heat to the argument over prehistoric dinosaur tissue.
An
article by Scientific American.
RALEIGH—Twenty
years ago, paleontologist Mary Schweitzer made an astonishing discovery.
Peering through a microscope at a slice of dinosaur bone, she spotted what
looked for all the world like red blood cells. It seemed utterly
impossible—organic remains were not supposed to survive the fossilization
process—but test after test indicated that the spherical structures were indeed
red blood cells from a 67-million-year-old Tyrannosaurus rex. In the years that
followed, she and her colleagues discovered other apparent soft tissues,
including what seem to be blood vessels and feather fibers. But controversy
accompanied their claims. Skeptics argued that the alleged organic tissues were
instead biofilm—slime formed by microbes that invaded the fossilized bone.
Schweitzer
and her colleagues have continued to amass support for their interpretation.
The latest evidence comes from a molecular analysis of what look to be bone
cells, or osteocytes, from T. rex and Brachylophosaurus canadensis. The
researchers isolated the possible osteocytes and subjected them to several
tests. When they exposed the cell-like structures to an antibody that targets a
protein called PHEX found only in bird osteocytes* (birds are descended from
dinosaurs), the structures reacted, as would be expected of dinosaur
osteocytes. And when the team subjected the supposed dinosaur cells to other
antibodies that target DNA, the antibodies bound to material in small, specific
regions inside the apparent cell membrane.
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