A
new face with a toothy grin now greets patrons of Notre Dame's
Eck Visitor's Center. A replica of the skull of "Peck's Rex,"
the Tyranosaurus rex fossil discovered in 1997 by a crew
led by Notre Dame paleontologist J. Keith Rigby, Jr., went on
display at the University in May. The 66-million-year-old Tyrannosaurus
fossil, which derives its name from its discovery site near Fort
Peck, Montana, made the national news when a ranch family claimed
ownership and attempted to dig it up before Rigby's crew could
excavate it. Subsequently, legal authorities established that
the family did not have title to the land and forced them to return
the skull and other bones to Rigby. Recently, we had a brief chat
with Notre Dame's dinosaur hunter.
NDM: Just how significant is Peck's Rex?
Rigby: There are approximately 25 known specimens
of Tyrannosaurus rex in the world. Of that number, five
or six are reasonably complete skeletons, 80 percent or more whole.
This specimen would be in that elite group. We have found some
pieces that are rarely found. We probably have the world's only
complete hand for a T. rex, including the very small
third finger which is about the same size as your small finger.
We also have the breastbone, akin to the wishbone in a turkey,
which is the critical feature linking the dinosaur to birds.
NDM: Were you surprised by anything when you
began analyzing the fossil?
Rigby: T. rex is supposed to be the
top dog of the dinosaur world, "Mr. and Mrs. Tough," that's the
popular image. But it might not have been the case. One of the
intriguing things we've found is that Peck's Rex has bite marks
all over its skull. It fought. We see evidence of wounds and cysts.
There are signs of arthritis in the jaw bones. It may even have
had a serious case of bone cancer. The overall impression is of
a creature not in good health. This is causing us to look at all
the other dinosaur specimens more closely. In fact, "Sue," the
famous T. rex in Chicago's Field Museum, has broken bones
and bite marks. T. rex did not have a white-collar lifestyle.
It lived in a tough neighborhood and survived by tooth and claw.
NDM: Finding Peck's Rex must be a high point
in your career.
Rigby: There's a piece of me that hopes we never
find another one. This has been very difficult. We've been assembling
and preparing it for display for over five years and we've just
now gotten to the point that we can begin to study it and publish
our findings. The problem is you can't analyze something sitting
in a block of rock. This particular fossil was so difficult because
the sediments surrounding the bones hardened shortly after the
skeleton's burial. Consequently, the bones never had any mineral
content added to them. That means the surrounding rock is much
harder than the bones, so recovering the fossil was like taking
concrete off of marshmallows. We use these miniature jack hammers,
about the size of a pencil, trying to knock off the rock and do
minimal damage to the bone. After the bones are cleaned, molds
are made and from these we make casts of the bones. It's the casts
that are assembled and put on display. The fossils themselves,
which have an estimated value of $16 million, are kept in a vault
at the Fort Peck Interpretive Center in Montana and are available
only to researchers.
NDM: Are you on the trail of any other dinosaurs?
Rigby: This summer, from the same hill where
we discovered Peck's Rex, we recovered a triceratops,
the plant-eating dinosaur that looks a little like a rhinoceros.
We also excavated a hadrosaur, a duck-billed plant eater,
and another human-sized dinosaur. Those were our three primary
targets this year. We have leads on half a dozen other things
as well. Besides dinosaurs we even have a fossilized stump of
a bald cypress tree that is 17½ feet in diameter at the base and
8 feet tall.
(October 2003)
