Bladensburg in Prince George's County, Maryland — The American Northeast (Mid-Atlantic)
Dinosaur Alley
One hundred million years ago, during the middle Cretaceous period, the Baltimore-Washington area was a flat plain near the sea, just as it is today. The climate, however, was warmer. The forests of that time consisted of conifers (pine trees and their relatives), cycad-like plants (conifer relatives that look like palms), and tree ferns. There were no grasses, briers, or oaks; flowering plants had not even developed yet. This was the home of the dinosaur.
During colonial times, iron-rich ore beds were dug by hand from surface pits. Occasionally dinosaur bones and other fossils were found, but the fossils' scientific importance was not understood at the time. The first dinosaur bones were said to have come from "iron mines in Bladensburg," but the actual site was nine miles north at Mulrkirk. These first discoveries (reported by Philip Thomas Tyson, state geologist in November 1858) were the bones and teeth of a large dinosaur named Astrodon johnstoni (Brachiosaur). Astrodon means star-tooth. It ws the first sauropod (a dinosaur with a long neck and a long tail) found in North America. In 1998, the Astrodon became Maryland's official state dinosaur.
At present, about a dozen categories of dinosaurs are known to be from Dinosaur Alley. These finds represent almost all the categories of dinosaurs. Nonetheless, it is generally believed by paleontologists that the fossils that have been found represent fewer than half the dinosaur species that lived in the Bladensburg area. There are many more species and skeletons to be found.
Topics. This historical marker is listed in these topic lists: Animals • Paleontology. A significant historical month for this entry is November 1858.
Location. 38° 56.115′ N, 76° 56.311′ W. Marker is in Bladensburg, Maryland, in Prince George's County. Marker is at the intersection of Annapolis Road (State Highway 450) and 46th Street on Annapolis Road. Marker is in Bladensburg Waterfront Park, .2 miles south of the entrance at this intersection. Touch for map. Marker is in this post office area: Bladensburg MD 20710, United States of America. Touch for directions.
Other nearby markers. At least 8 other markers are within walking distance of this marker. The Incidental Cause of the Star-Spangled Banner (1814) (here, next to this marker); Duels and the Bladensburg Dueling Grounds (a few steps from this marker); Encampment of Coxey's Army (1894) (a few steps from this marker); Historic Bladensburg Waterfront Park - Port Town History (within shouting distance of this marker); First Unmanned Balloon Ascension (1784) (within shouting distance of this marker); Colonial Ropemaking (within shouting distance of this marker); The Battle of Bladensburg (1814) (within shouting distance of this marker); The First Telegraph Line (1844) (within shouting distance of this marker). Touch for a list and map of all markers in Bladensburg.
More about this marker. The marker displays a drawing of two young Astrodon johnstoni, a map of "Dinosaur Alley," and a drawing of a tooth of Astrodon johnstoni (actual size 1 3/4 inches in height).
Credits. This page was last revised on October 21, 2020. It was originally submitted on July 18, 2010, by Craig Swain of Leesburg, Virginia. This page has been viewed 2,678 times since then and 37 times this year. Photos: 1, 2, 3. submitted on July 18, 2010, by Craig Swain of Leesburg, Virginia. 4, 5. submitted on August 3, 2013, by Allen C. Browne of Silver Spring, Maryland.