Dinosaur National Monument, on the border of Utah and Colorado, is home to one of
the greatest dinosaur quarries ever discovered. It is perhaps the world's finest
display of fossils in-place available to the public.
The monument also protects
many miles of gorgeous canyon country. The confluence of the Green and Yampa
Rivers, known as Echo Park, is one of the west's most beautiful places. Huge
environmental battles were fought in the past to preserve this area - the Yampa
River is the only remaining free-flowing river in the Colorado River system.
Photo, above: a scenic stretch of the Green River near the Dinosaur Quarry.
Photo, left: Echo Park (courtesy, National Park Service).
The quarry was originally discovered in 1909 by paleontologist Earl Douglass
of the Carnegie Museum in Pittsburgh. He worked the find for many years, sending
spectacular specimens back to the museum, which included many nearly intact (articulated) skeletons.
Many of the fossils were from the giant sauropods of the Jurassic era (about 150
million years ago at this site) of dinosaurs
such as Apatosaurus (formerly Brontosaurus). Eventually, the National Park
Service took over the quarry and redeveloped it for public display. A field house / visitor
center was built over the open hilltop quarry, and about 1,500
bones were exposed in place.
Photo, right: The Dinosaur Quarry and Visitor Center. Photo, above left: the vista
from the quarry.
The site is at the top of a small but steep hill in an area
of colorful badlands. The present exposed area is about 100 meters long and
20 meters high on a steep wall (photo, left). The original excavators dug away much of the
original hilltop in their quest for the bones. The photo, right, is a closeup
of the left end of the wall. The sharpness of the shot has been exagerated
so the imbedded bones are clearly visible. Note the gigantic sauropod leg bones
in the far right of the shot.
The site is rich in sand and gravel indicating that the dinosaur carcasses
were trapped at the bottom of an ancient river. The large number of bones
probably collected during periods of flooding and were then covered quickly
by sand and gravel. Perhaps a sand bar or bend in the river caused so many
bones to collect in one place.
The ancient environment was semiarid but warm year round. The area was a vast plain
with rivers flowing in shallow valleys from a high mountain range to the west.
The riparian areas around the river beds provided excellent habitat for large animals.
How did a river bottom end up at the top of a steep hill? The river bed
was buried under many layers of debris over the eons. However local geologic
forces bent many layers upward into nearly vertical positions with the
appearance of a steep hill. More eons of erosion wore off the top of the
hill, eventually exposing the edge of the fossil layer. Vertical rock
layers can clearly be seen in the photo at the top of this article
(on the far side of the river).
(At left, a happy stegosaurus in the gardens at the Utah Field House of Natural
History in nearby Vernal, Utah. The museum is an example of the numerous
first-rate small town museums in Utah and is definitely worth a visit.)
The two-tiered gallery provides excellent viewing of the wall. The park service
offers brochures which describe all of the exposed bones. The rear of the gallery
has various exhibits including casts of some of the most spectacular finds
ever taken from the quarry, including the most complete sauropod skeleton ever found
and the largest allosaurus skull ever found. Photo, right: a nice closeup of
a huge leg bone; at left, a human comparison from the Utah Field House. Note
the bone to the right and above the person.
Below left, an intact skull and neck of a small sauropod. Intact skulls are
extremely rare in the world of dinosaur fossils. The bones of the skull
were very light and fragile compared to their generally huge leg and torso bones, so they
tended to fall apart quickly after decomposing. At right, an articulated skeleton recently found
nearby. It was thought to be a newly discovered species of theropod (meat eater).
Note how the entire matrix (work area) was carved out of the ground then wrapped in plaster
to be moved. The top of the plaster was removed so the find could be temporarily
displayed in the field house.