RAPID
CITY, SD (Nov. 10, 2020) — Some 65 million years ago he stalked what is now northwestern
South Dakota, no doubt earning his nickname the “Tyrant King.”
In
all likelihood, this Tyrannosaurus rex specimen took his last step and last breath
near Mud Butte in Meade County, less than 100 miles north of Rapid City. Today,
one of his jaw bones rests safely inside a plaster fiberglass jacket in the James E. Martin Paleontology Research
Lab
(PRL) at South Dakota Mines. Measuring about 2 ½ feet long, the
jawbone weighs in at 30 pounds. His teeth, dark and smooth, measure 5 ½ inches
long.
Another
piece of the jaw belonging to Mud Butte T. rex is being staged for an exhibit in
the lab’s storage area, a room bursting with shelves of paleontological
treasures yet to be prepared. The Museum of Geology on campus displays the remainder of his
skull – on a table sandwiched between two marine reptiles. His presence is so
innocuous that one museum staff admits she sometimes forgets to mention him to
guests.
Kayleigh
Johnson, lab manager and preparator, hopes to change that.
Johnson
has a dream that one day, the T. rex skull will be displayed in all its glory.
“But it’s going to take more work and a lot more time,” she says.
One
of the largest known carnivorous dinosaurs, the T. rex lived during the late Cretaceous
Period. Known for its short arms and menacing teeth, its name literally means “king
of the lizards” (tyrannosaurus means tyrant lizard and rex means king).
Sixty-five
million years ago, T. rex and countless other dinosaur species roamed what is
today northwest South Dakota. The Hell Creek Formation, which runs through
Montana, Wyoming, South Dakota and North Dakota, has produced a gold mine of fossils.
The
Mud Butte T. rex was the sixth of its kind ever found. This particular Tyrant
King was discovered during the summer of 1981 by Shirley and Jennings Floden,
owners of the property and fossil enthusiasts. Teams lead by then museum
director Phillip Bjork worked to excavate the T. rex through 1983.
The
Mud Butte T. rex has been at South Dakota Mines ever since.
Since
the fossil was initially prepared at Mines, techniques have evolved and
improved, Johnson says. As a result, Johnson is working to conserve him for long-term
storage and display. “We have better techniques,” she says. “But they did a
great job for the time period.”
Her
work includes chipping away papier mache, some epoxy and a “mystery mesh” found
along the jaw. The acidic levels of this particular papier mache causes damage
to a fossil, so Johnson will meticulously remove it and reassemble the pieces
using modern materials such as Paraloid B-72. The material has excellent aging
properties and can be easily reversed if needed. “You want to make sure
everything is as chemically inert as possible,” she says. “I’m taking it apart
piece by piece.”
While
Johnson has only had time to work on the jaw bone for short periods – “It’s
like my on-the-side job,” - she estimates that it would take two months of full
8-hour days to complete the prep on just this one jaw bone. But Johnson is not
discouraged. Until the work can be completed, she plans to display the other
jawbone in the atrium of the Paleontology Research Lab as part of a new exhibit
“History of the Museum of Geology Exhibit,” which should be ready by the end of
the year.
The
skull will remain on display in the Museum of Geology, and Johnson recommends
checking it out. “This specimen is really an amazing find and needs to be more
well known, not only for visitors’ sake but also for those who want to research
it,” Johnson says.