Dinosaur fossil found underneath a Denver museum’s parking lot

Colorado tends to be the sweet spot for Cretaceous fossils due to the number of rocks from that period near the surface that volcanoes haven’t harmed or faults haven’t broken up, researchers said.

Editor's note: Taylor Nicioli is a freelance journalist based in New York.

(CNN) — The phrase “leave no stone unturned” has taken on new meaning for paleontologists at the Denver Museum of Nature and Science who discovered a special fossil hidden right under their noses — beneath the museum’s parking lot.

The dinosaur bone came to light in January during a drilling project to study the layers of rock underneath the site, the museum announced on July 9. The team had planned to pull an Earth core sample, a long cylindrical piece of rock or sediment, and came across a partial fossil.

At about 2.5 inches (6.4 centimeters ) in diameter — the width of the extracted rock core — the disk-shaped specimen is the vertebra of a plant-eating dinosaur that roamed the region more than 67 million years ago. At a depth of about 760 feet (230 meters) below the surface, it is the oldest and deepest fossil ever found within Denver, according to the museum’s release.

There is not enough of the fossil to determine its species, but this rare find helps fill in a picture of the ecosystem during the Cretaceous period in what’s now Denver, said Dr. James Hagadorn, the museum’s curator of geology. Scientists were able to narrow the fossil down to an herbivorous group of bipedal dinosaurs known as ornithopods, and it’s the first ornithopod to be found in Denver’s city limits.

“We knew those dinosaurs were (nearby in other parts of) Colorado or Wyoming, but we didn’t know that they were in Denver, too … but we suspected it right at this time period,” Hagadorn said. “Now, we have another plant eater that’s been cruising around Denver munching on, who knows, gingers and palm leaves and other ferns and plants 67 million years ago.”

Coring for dinosaur fossils

The unexpected addition is now on display at the Denver Museum of Nature and Science, which has around 115,000 dinosaur, plant and mammal fossils in its collection, according to its website. Since there are only two other instances in the world of a dinosaur bone having been uncovered in a core sample, Hagadorn said he believes the newly found vertebra is the first to be put on display.

More of the ornithopod fossil remains underground, but there are no plans to excavate the deeply buried specimen, Hagadorn said. “Unfortunately, we can’t excavate our entire parking lot. Parking is really important at the museum and in all cultural (centers ),” he said. “But the bonus here is that people can now park right on top of a dinosaur.”

The drilling project’s initial purpose was to investigate whether the museum could switch from natural gas to a geothermal energy system. Researchers still have about 1,000 feet of extracted rock core left to analyze — which could contain fossils, minerals or other structures that weren’t visible on the core’s exterior, Hagadorn said. Further study of the sample will also help experts at the museum better understand the region’s geology and other environmental factors such as drinking water.

While studying the rock core has many purposes, finding a dinosaur fossil was not something the team expected, Hagadorn added. “It’s like the lucky strike. I mean, who would have figured? … It’s like Robin Hood splitting an arrow in half, or an apple, from 2 ½ football fields away.”

Even without the full fossil available, the small bone allows scientists to better understand the diversity of dinosaurs that once roamed the Denver Basin near the end of the Cretaceous period, Hagadorn said. He likened it to a diorama that has one more confirmed character added to the picture.

Colorado Cretaceous period

The finding is a “nice example of how dinosaur fossils are distributed around in our environment, even in … places that might seem unlikely, like in the middle of the city of Denver,” said Dr. Paul Olsen, a paleontologist and Arthur D. Storke Memorial Professor of Earth and Environmental Sciences at Columbia University. Olsen was not involved with the discovery.

“It’s illustrative of how dinosaur bones and other fossils are really not terribly rare, and anytime you have a really good way of viewing the rock … you will run into fossils,” he added. “And fairly often, if (the rock) is the right age, you’ll run into dinosaur bones.”

Most often, rock coring is performed after a fossil has been discovered, because it can give scientists a better look at the layering within the rock and what the environment was like millions of years ago, Olsen said.

Colorado tends to be the sweet spot for Cretaceous fossils due to the number of rocks from that period near the surface that volcanoes haven’t harmed or faults haven’t broken up, Hagadorn said.

In light of the parking lot discovery, paleontologists were inspired to go back and look at available satellite and elevation data to date all other fossils previously found within the Denver metro area, including a Tyrannosaurus rex, Triceratops and Torosaurus, and other major fossil deposits. Before that analysis, the team only knew that the ornithopod vertebra was from the Late Cretaceous period. With the new data, which was published in June in the journal Rocky Mountain Geology, researchers were able to give the newly discovered fossil, as well as others included in the study, a more precise age.

“No one ever dated these things before,” Hagadorn said. “It wasn’t very feasible to do that in the past, but today, we were able to use some specialized maps, geologic maps, GIS (geographic information systems) and really precise elevations that you can now get from satellites to place all these things in space and then in time.”

While most fossils within the study were found in more rural areas, the ornithopod vertebra highlights remaining fossils yet to be discovered, particularly in untapped urban areas. Discovery of the bone within the core, and the use of more precise dating techniques to understand its place in time, allows for better understanding of the changing world, Columbia’s Olsen said.

“These kinds of studies give humans context of where they fit in the history of the universe and the history of the world,” said Olsen, who also didn’t participate in the new analysis.

“It documents the changes through time that occurred, and sometimes we learn really astounding things. … And at a much more granular level, it gives us ways of trying to understand how the world actually works, in terms of developing hypotheses of climate change (or) hypotheses of mass extinction,” he added. “So all of this gives us context for understanding, and sort of a library of reality, to go compare our theories with.”

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