Over 100 Dinosaur Tracks From 150 Million Years Ago Discovered in Colorado

More than new 100 dinosaur tracks dated to around 150 million years ago have been uncovered at a renowned site in Colorado.

Clean-up crews discovered the tracks at the Picket Wire Canyonlands, located in the southeast of the state, after flooding, the Colorado Springs Gazette reported on Tuesday, citing U.S. Forest Service officials.

Picket Wire Canyonlands, which lies in the Comanche National Grassland, is home to the largest dinosaur track site in North America, containing more than 2,100 individual footprints across 130 separate trackways, according to the Forest Service.

The tracks are found across a quarter-mile stretch of bedrock along the banks of the Purgatoire River.

The tracks were made by dinosaurs around 150 million years ago during the Jurassic Period, when southeastern Colorado's climate was tropical and the region was home to forests of tree ferns, ground ferns, pines and sequoia trees.

At that time, the Purgatoire River Valley formed part of a huge shallow lake. And on the muddy shores of this lake, several dinosaur species used to roam, leaving behind tracks that fossilized under the right conditions and, thus, can still be seen today.

After the Purgatoire River flooded this summer, the dinosaur tracks at Picket Wire Canyonlands were covered in several inches of mud and debris.

This prompted specialists and volunteers to start cleaning up the site using shovels and excavators in order to make the tracks visible again.

It was during this clean-up process that crews uncovered the new tracks. Bruce Schumacher, a paleontologist from the Forest Service, told the Gazette that between 100 and 150 tracks had been identified by crews.

The paleontologist said the tracks were likely made by creatures belonging to the Brontosaurus group of dinosaurs. These animals were very large dinosaurs with long necks and tails that lived during the Late Jurassic Period from about 156 to 145 million years ago.

John Linn, a Comanche National Grassland district ranger, told the Gazette: "Every track down there is a national treasure. I hiked it just yesterday actually. It never ceases to amaze me. I'm always overcome with awe when I stand in those tracks that are 150 million years old."

The round-trip hike to the dinosaur tracks is 11.2 miles long, starting at the Withers Canyon Trailhead. From the trailhead, hikers descend 250 feet into the canyons.

The site was initially mapped in the 1980s, but since then over 800 new tracks have been revealed, bringing the total count to 2,100.

Most of these have been uncovered during clean-ups like the one that revealed the latest finds.

This summer, "there was an event that flooded an area that had not yet been mapped and recorded," Schumacher said.

The tracks "could continue for a long, long time," he said. "But we've kind of reached a point where we've got a good amount exposed. At least I feel like we're at a place to continue to manage it as it is."

Schumacher told Newsweek there are two main types of dinosaur tracks preserved at the Purgatoire River site.

"The most obvious are large sauropod tracks made by huge quadrupedal herbivores," including brontosaurus," he said. "Other numerous and distinctive tracks are theropods—bipedal meat-eaters like Allosaurus. There are a few ornithopod tracks preserved, duck-billed-type dinosaurs like Camptosaurus."

Schumacher said the site is "quite simply the largest assemblage of Jurassic age dinosaur tracks known anywhere in the world."

The site provides "strong evidence" that sauropod herds consist of adults and juveniles, indicating some kind of family structure, according to the paleontologist.

The preservation of dinosaur tracks in a muddy or wet substrate, such as the shore of a lake, requires a specific series of events.

"Just like a person's footprints in sand while walking along a beach, most tracks made in wet sediment are erased by rain, wind, or waves before they are preserved," Schumacher said. "The dinosaur tracks at Picket Wire Canyonlands were likely preserved because once impressed into the mud, they were dried and baked hard in the sun.

"The water level in lakes naturally fluctuates seasonally, rising and falling with rainfall or drought conditions. So dinosaur footfalls preserved in dry mud were eventually flooded by rising lake level and covered by additional sediment."

UPDATE 11/24/2021, 9:14 a.m. ET: This article was updated to include additional comments from Bruce Schumacher.