Dinosaurs Roamed Near Nation's Capital

Feb. 26, 2008 -- Until recently, evidence for dinosaurs in the northeastern United States was sparse, but over 900 theropod, sauropod, ankylosaur and ornithopod fossilized footprints have now been found just a short drive from the nation's capital, according to new studies.

The finds, which also include tracks for pterosaurs, a dino-era mammal and other vertebrates, suggest that Maryland was a hotbed for dinosaurs during the Cretaceous from around 98 to 121 million years ago.

"Based on the trace fossils, over two dozen species of dinosaurs were living in Maryland at that time," co-author Ray Stanford told Discovery News.

"Like my wife said the other day, 'These animals were everywhere,'" Stanford, a dinosaur tracks specialist from College Park, added.

He began to discover the Old Line State dinosaur footprints while looking for Native American artifacts along streambeds with his children. Stanford, whose living room is full of the tracks, explained that as water and human development erode such beds, "floats" can result. These are pieces of track-bearing substrate that hydrodynamically dislodge from their natural stratigraphic context during stream bank flooding.

"This is one instance where building booms and storms can benefit science," he said.

All of the discoveries were made either in Prince George's County, near Washington, D.C., or at the White Marsh Run area of Baltimore County.

So far, Stanford has described and published Maryland's first dinosaur track species (called an ichnospecies which translates to 'trace species'). It consists of both front and back footprints of a hypsilophodontid dinosaur. He named the new dinosaur footprint type or species Hypsiloichnus marylandicus, meaning "trace of a hypsilophodontid dinosaur from Maryland."

Another highlight from the finds is one of the oldest known mammals from North America. Stanford and his colleagues have not yet identified the species, but they believe it was a very large marsupial. An imprint of reptile skin, possibly belonging to a dinosaur, appears next to the tracks.

"The mammal probably stopped to smell a dead dinosaur while looking for something to scavenge," Stanford explained. "This animal--at least the size of a large German shepherd--probably would have been big enough to take down a dinosaur."

An overview of these, and other, finds was recently published in the journal Ichnos.