Paleontologists Uncover Nine-Ton Trove Of Utahraptor Remains

Jan 15, 2015

Inside a nine-ton sandstone block pulled from a mesa outside of Moab could be the key to knowing how the carnivorous Utahraptor lived. But before paleontologists can figure that out, State Paleontologist James Kirkland says they are going to have to find a place where they can start chipping away at the block.

The partially-feathered, polar bear-sized dinosaur lived during the Cretaceous, around 125 million years ago. Kirkland discovered the first specimen of Utahraptor in 1990. Then, in 2001, Kirkland said a geology student hiking around the Cedar Mountain Formation made the critical discovery that lead to the excavation of the nine-ton block.

“We had a student working on the geology out there and I told him [to] look for bones.  He’s a geologist, not a paleontologist, and he came out of the projects and said, ‘Well, I really didn’t see much, but there was one place where it looked like there was a human arm bone sticking out of the ground’,” Kirkland said.

Kirkland went out to the site and uncovered a few bones, but it wasn’t until a few years later when there was a rock fall that the larger group of fossils was exposed.

“We looked into the crack and said, ‘Wow, that looks like some bone there!’ And as we looked closer we realized there were teeth! ‘Wow, there’s a big meat-eating dinosaur jaw going through this broken chunk!’ And we realized we had the first lower jaw of a full adult Utahraptor meat-eating dinosaur, and we had a brain case,” Kirkland said.

It turned out the sandstone was so dense with fossils that it was impossible to excavate in the field. That’s when, with the help of Cross Marine Projects, Kirkland figured out a way to excavate the block in one piece and transport it to Salt Lake City.

Kirkland said they’ve identified six Utahraptors so far, and that’s just on the surface of the block.

“It’s so solid with skeletons, you can’t put an ice pick into it without hitting strings of vertebra, feet or hands,” Kirkland said. “To chop it would have been just tragic because we don’t know a lot about Utahraptor.”

How all of these dinosaurs ended up being fossilized together was a bit of a mystery for the scientists. Usually when fossils are found in sandstone it is a telltale sign of a river, lake or desert, but in this case, the sand wasn’t continuous; it was what Kirkland calls a big blob caused by a dewatering feature—quicksand.

Dinosaurs in quicksand had never been documented before. The sand preserved the bones extraordinarily well, and because of this, Kirkland and other paleontologists are hoping the block will answer some long-held questions about the Utahraptor.

“There’s been theories that these animals are pack hunters, so did it attract the pack? If that’d be the case I would expect to see the ages of the animals to be somewhat age-segregated,” Kirkland said. “Our theory is that adult pair of Utahraptors would have a nest, have their babies, the babies would follow them like ducklings.”

Kirkland said the block may also finally give scientists a glimpse of the Utahraptor’s feathers.

“As we expose arms that are still intact, we’re going to go minutely slow. Everything is going to be done under microscopes because the feathers are there and we’re seeing this very beautiful preservation; we have a good shot of finding that.”

The sandstone block is so big that Kirkland has had a hard time finding a building that can both physically fit and support it.

For now, it sits in a parking lot in Salt Lake City.

The location will likely soon change as negotiations are underway to form a partnership with the North American Museum of Ancient Life at Thanksgiving Point. That location would provide a glass-front lab for scientists to conduct their work in while the public watches. Once fully excavated, the specimens will be displayed at the Natural History Museum of Utah.