|
|
The Story of Ms. Spike
June
1992
Kenneth Carpenter, Dinosaur Paleontologist and Chief Preparator at the
Denver Museum of Nature and Science, was conducting a two week long
field camp in the Garden Park Fossil Area.
His assistant, Bryan Small was prospecting one evening with
volunteer Tim Seeber in a narrow canyon.
He poked his rock hammer into a likely looking exposure and
pulled out the neck vertebra of a Stegosaurus
dinosaur.
As
usual in paleontology fieldwork, the finding of an important specimen
(and in this case a potentially very large one), reorders the field
camps priorities. Ken Carpenter assigned the excavation of the new site to Bryan
and the next day he and a crew of diggers was dispatched to the new site to explore the extent of the
find. Because the two week field session was already half over, work proceeded with "careful
haste" to uncover the extent of the specimen.
Excitement
built as the neck vertebrae were unearthed in succession and joy erupted
as they led to the rarest of finds, an apparently intact skull.
Careful
work was necessary as the fragile bone was exposed and hardened.
While picks and shovels dug away the side of the hill, small
probes, soft brushes and dilute plastics were the most used tools once
the bone was uncovered.
At
the same time, part of the crew worked to fully excavate, jacket and remove
the skull from the field as quickly as possible.
The chance that something might happen to this most important part of
the specimen before the crew could return to the field later in the summer to
finish the excavation were too great.
The sad realization also came that as we dug back into the hill
following the bones, we would have to close up the quarry and leave before
determining if the skeleton had a complete tail.
August
1992
When
the quarry was closed up in June we all knew that somehow the
museum would find a way to change its lab schedule so that
Bryan
could return to finish the dig.
The find was too important to leave for another year.
Sure enough, in August,
Bryan
returned and with a few volunteers from the
Denver
area and a few more members of GPPS, we went back to work.
The
backbreaking work of extending the pit yielded the first excitement of the
renewed dig. The tail was complete
and articulated, with three of the four spikes in place.
This was proving to be a very exciting specimen.
The
farther the dig progressed and the more complete the specimen
proved to be, the more reluctant the scientists and crew became to
“carve” it into small pieces to get it out of the quarry.
We
began to think out loud…”it had never been done before…. the
canyon is very difficult to access…there must be a way to get it
out in one or two pieces”. One of the volunteers came up with the idea of having the
Army lift it out with a big helicopter. As we batted around the absurdity of that idea it occurred
to us…if we asked it wouldn’t hurt…and they might just
say…YES!
Back
at the museum, Ken Carpenter began the calls to Fort Carson and indeed was not turned
down, as we had feared. After many calls and a progression up through the chain of command at the
Fort, things began to look promising. The question now became how to make such an enormous jacket and
free it from the ground with the hand techniques we had been using.
With
the help of Dan Grenard of the BLM and Bill Tezak of Colorado Quarries
of Cañon City, machinery took over the hard work of digging and the
museum crew was able to devote time to plastering the jacket.
As miners dug under and installed beams, the field crew moved
in to plaster everything in place.
In two weeks, a job that we thought would take months, was
suddenly finished and the Army arrived to check out their up coming
mission, lifting a dinosaur.
Finally
all was ready and the pilot began the mission’s task, just slide the
six and one half ton body jacket out from under an overhang on the
tail jacket and then lift it without banging into the narrow quarry
walls. All this was under
the verbal command of the mission load master, because the pilot could
only see in front of his helicopter.
Mission
accomplished, and the Stegosaurus flew down the canyon while everyone on the ground
experienced the biggest case of goose bumps ever.
After
flying out of the canyon, the Army went back to work with the Colorado
Quarries crew. One
more lift with a much shortened strap, and the jacket was gently laid
on the truck for its trip to storage in
Cañon
City
to await the opening of the
Dinosaur Depot.
This is the beginning
of the tail which was twisted straight up as the animal rotted.
The rest of it was separated in the field and taken to the
Denver Museum of Nature and Science for preparation.
In
Denver
the work on the tail revealed the probable cause of the Stegosaurus’
death, a very bad infection in a tail spike.
Notice the spike on the right side of the picture.
It is shortened and flattened.
The bone also looks very “waxy” and unhealthy.
A team of paleopathologists has been studying this bone to add
to the information about the relatively new science of paleopathology.
It is another way to gain information from fossils to get a
better picture of how extinct animals lived.
Much of the top
of the body jacket of the specimen has been prepared at this point.
This is the rib area where the vertebrae are in place with
the right ribs, while flipped up and flat, still in or near their
attachments on the vertebrae.
This
is the left pelvic area where the femur or upper leg bone is still
in place at the junction of the three bones that form the hip socket
structure. The animal rotted after it died and before it was buried, so
the bones are very squashed looking.
Many
thousands of visitors came to the Dinosaur Depot Lab to see the work
in progress, over 10,000 during the first summer. Some local residents came often to keep track of the progress
being made by the volunteer preparators.
At
the end of the summer of 1996, the specimen was completely prepared
from the top.
The
next step was to make a new jacket and frame for the top of the
specimen and then turn the whole thing over, so that the bottom
could be prepared. The
bone, no longer protected by the rock that imbedded it for 150
million years, needed to be carefully protected.
In addition to the stress of the nearly 6 ½ ton jacket being
turned over, there would be vibrations and shocks from the
preparation of the bones on the other side of the specimen.
To accomplish this, two layers of plastic wrap were put on
the surface of the bone, then the space that was filled with matrix
was refilled with sand and chunks of plaster packed in snug enough
to keep everything from shifting.
The back plates, which are very thin and fragile were given a
little extra padding and reinforced with pieces of plywood.
In all, four heavy layers of plaster and burlap were used to
cover the entire top of the specimen.
Next a frame was
made of 4x4’s and 6x6’s, with the gaps between the boards and
jacket filled with more plaster and burlap. On the day of the
turnover, once again the crew from Colorado Quarries came through
with their professional expertise.
They pulled it
out into the street on 2x4 skids and loaded it on a truck.
After
transport to the quarry yard, the new and old frames were strapped
together and then the whole thing was turned over on a pile of sand.
It
was then loaded back on the truck for its return to the laboratory
at the Dinosaur Depot, where volunteers were ready to begin work on
the bottom side.
This
is the specimen totally prepared from the bottom.
To the left is the neck.
To the right the beginning of the tail can be seen going down
under the enormous hip plate.
This plate is upside down in the upper right corner of the
picture.
There is another plate, also displaced, in the center of the
picture.
Perhaps the flood, which buried the carcass, moved it after
the skin integrity had rotted, but before the connective tissue,
which holds the bones together lost its integrity.
It is this kind of question which the scientists work toward
answering, as they study the death to preservation processes or
taphonomy of fossil carcasses such as this one.
With preparation of the specimen complete, much more intense
study of it has now begun.
Composite
exhibit of the jackets and loose parts of the DMNH 2818 Stegosaurus stenops on the occasion of the Society of Vertebrate
Paleontology’s 1999 Annual Meeting at the Denver Museum of Nature
and Science.
After
getting the cast of Spike from the Denver Museum of Nature and
Science, there was much work to do.
After grinding the edges and seam lines...
Filling
cracks and holes with epoxy...
And
several coats of various colors of paint later, the cast is ready
for display.
The
replica cast is seen as it appears on the wall of the Dinosaur Depot
Museum. The first
picture is the skull with the neck plates and the throat area lined
with ossicles.
The
next picture shows the body with more of the plates.
This
picture shows the tail with plates and spikes, including the
infected and broken spike located on the bottom.
Click
here to return to Featured Exhibits
|
