Trail leads to fossil discovery
Survey work for Palisade Plunge unearths dinosaur bone
Government officials conducting early surveys for the Palisade Plunge bike trail made an exciting discovery this past spring — a large lower leg bone from a dinosaur.
The bone is likely from a hadrosaur, a duck-billed dinosaur that thrived here 70 million years ago, experts said.
Last week a team of Bureau of Land Management members, a local paleontologist and a sedimentologist climbed up to the spot above the Palisade Rim trail where the bone was found and removed it, taking it to a lab at the Museums of Western Colorado, where it could be cleaned up and studied.
The fossilized bone was first seen by BLM Outdoor Recreation Planner Chris Pipkin in April while he scouted out the likely route for the Palisade Plunge trail across public lands above the valley. He saw it sitting in the open face of a boulder right alongside the future bike path.
“The actual trail comes within five feet of this bone,” said Eric Eckberg, the BLM geologist who coordinates paleontological findings on local public lands, as he stood next to the exposed fossil early Thursday morning.
The splotched, brownish bone is about the width of a human forearm and just more than 2 feet long. It was truncated at one end, where a portion of it would have likely broken off when the boulder it was embedded in split open — perhaps as it tumbled from the clifftops above Palisade toward the valley floor.
Eckberg said the Palisade Plunge bike route travels through important geological areas, including parts of the Hunter Canyon Formation, a layer of rock in the Grand Valley area that dates back to when tyrannosaurs and triceratops roamed the earth, in the last days of the dinosaurs.
It’s in this type of gray, silty rock that the hadrosaur bone was found.
The experts and officials wanted to extract the bone from the boulder because of the high use expected on the Palisade Plunge trail once it opens. If the bone is “snatched up” or worn down by the hands of visitors over time, local and worldwide communities will lose out on knowledge, they said.
The fossil is an important historical resource, said paleontologist Josh Smith, who hiked up to lead the extraction process.
“This is how we know about dinosaurs,” Smith said, standing over the fossil. “The bone itself represents a living being from 70 million years ago.”
Smith and the other team members collected not only the bone but also the surrounding pieces of rock that encased it. All these materials, Smith said, can help scientists piece together the whole ecosystem in which the ancient animal lived.
While it might seem like dinosaur bones are rife in this area, only a fraction of a percent of bones from all the dinosaurs who ever lived gets discovered, the team said.
“For all we know, this is the only lower limb hadrosaur bone from the Hunter Canyon Formation anywhere,” said Smith, who’s been working as a “freelance” paleontologist in the Grand Valley for 10 years.
As for how Smith could guess the species of dinosaur from what he could see of the bone in the boulder, he said he followed a process of elimination. The bone didn’t have the right shape or size for a meat-eater or a horned or armored dinosaur, he said.
But the bone could be from an animal closely related to, but lesser known, than a hadrosaur. It’ll take a close look at the lab to be more certain, Smith said.
The team began to cautiously chip away at the large boulder containing the bone before the morning sun hit the slopes above Palisade. They chipped at the rock holding the bone for five hours, until, at about 40 pounds, it was a small enough package to backpack down off the mountain.
Chunks of the Hunter Canyon rock that were cleaved from the boulder were studded with charcoal-like plant impressions and ancient shells. The freshly opened slices of rock smelled of damp, loamy soil.
Eckberg said the animal to which the bone belonged may have been caught up in a mudslide, perhaps caused by a flash flood like those that have lately been terrorizing northern Arizona. With time and pressure, the soil containing the dinosaur turned to rock.
Many interesting discoveries are coming from different Hunter Canyon dig sites on the Western Slope, Eckberg and Smith said.
“It’s becoming more and more obvious the Hunter Canyon Formation has a lot more fossils to give,” Eckberg said. “It’s just a matter of finding them.”
They haven’t found a T-Rex in this area yet, but Eckberg is fairly certain that with enough effort, they will. He said “even experts miss things,” and it’s very possible more fossils or other valuable resources might be found by the public once the bike trail is in use.
The Palisade Plunge trail project — a 30-mile, 6,000-foot mountain biking route from the top of Grand Mesa to Palisade — is a paragon for the type of balanced usage the BLM aims to maintain on public lands, Eckberg said.
Trail surveyors have already re-routed the “rough draft” of the Plunge to avoid an eagle’s nest, several bunches of a threatened species of cactus and a prized hunting area near the Grand Mesa top.
“We need to build it in a way that’s respectful to all the resources in the area,” Eckberg said.
He added that the bone was found at the very beginning of the environmental assessment process, and there’s still much more careful and conscientious work to be done as the trail moves toward completion.