Washington, Feb 27 : Strong evidence for the existence of dinosaurs in the northeastern United States has been found, with over 900 theropod, sauropod, ankylosaur and ornithopod fossilized footprints discovered in Maryland, a region near Washington D.C.
According to a report in Discovery News, 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.
Stanford began to discover the old line state dinosaur footprints while looking for Native American artifacts along streambeds with his children.
According to him, 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.
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. 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," explained Stanford. "This animal--at least the size of a large German shepherd--probably would have been big enough to take down a dinosaur," he added.
Analysis of the region's geology indicates that during that dinosaur era, fresh water sources and plant life would have been plentiful.
Given the proximity of the recent discoveries to the nation's capital, it is even possible that evidence for dinosaurs rests at, or near, the Smithsonian and other D.C. landmarks.
"I've seen likely traces from a distance," said Stanford. "I'm confident I could find dinosaurs in D.C.," he added.