Morrison – The state’s first footprints of a stegosaur – Colorado’s official fossil – have been discovered near this foothills town 15 miles west of Denver.
Two new dinosaur track sites found by staff and volunteers of the Morrison Natural History Museum also include footprints made by two or three not-yet-identified and potentially new dinosaurs.
“We couldn’t believe what we were seeing,” said Matt Mossbrucker, museum director and dinosaur researcher. “They were basically hiding in plain sight.”
The tracks range in size from ones that can be covered by a dime to ones big and deep enough in which to bathe a baby.
Mossbrucker painted a picture of six or seven species of dinosaurs – some as small as sparrows and others with the combined bulk of eight elephants – making the imprints while walking in wet river sand about 150 million years ago.
Aside from a system of shallow Platte-like rivers and shallow ponds, the Morrison area’s landscape in the Jurassic featured few plants, a dry environment that served as an area to walk through to get to someplace with more to eat.
An even rarer discovery is blocks of concretelike sandstone containing a combination of fossilized dinosaur bones and tracks.
Some of the track- and fossil-bearing blocks of rock have been removed and are being studied and displayed at the Morrison museum. The track sites will not be open to the public because of safety concerns.
“You never, ever get footprints where you get bones,” said Robert Bakker, an internationally known paleontologist and scientific adviser to the museum.
Morrison is steeped in prehistory, with the first dinosaurs in the western United States discovered there. Among the original Morrison finds are Stegosaurus armatus, diplodocus, allosaurus and Apatosaurus ajax.
On the east side of Dinosaur Ridge are the tracks of an iguanodon-like ornithopod that lived in the Cretaceous period, which was 40 million to 50 million years later than the creatures whose footprints were recently discovered.
The discoveries were made in one of 10 fossil quarries opened along Dinosaur Ridge in 1877 by Arthur Lakes, a part-time professor at what became the Colorado School of Mines.
After yielding hundreds of tons of fossil-containing rocks for Yale’s Peabody Museum, the quarries were closed by 1879, and dinosaur hunters moved on.
Grants from the Scientific & Cultural Facilities District and Aggregate Industries triggered a re-examination of one of the old quarries beginning in 2003.
Mossbrucker said researchers were looking for fossil bone, flipping over boulders when the tracks were uncovered.
“There is a very rich tapestry of geology and paleontology in the Morrison area,” Mossbrucker said. “You don’t need to travel to find important fossils. We just need to look in our own backyard.”
Staff writer Ann Schrader can be reached at 303-278-3217 or aschrader@denverpost.com.
