Long before the Chesapeake Bay or I-95 corridor etched the land that would be Maryland, an enormous carnivorous dinosaur lived and died here.
About 115 million years later, staff and volunteers at Prince George’s County’s Dinosaur Park say they have unearthed a tibia, or shin bone, belonging to that apex predator of the early Cretaceous Period.
Officials announced this week that the recovery of the fossil and others nearby elevate the park’s classification to a bone bed, the first discovered in Maryland since 1887. Paleontologists define a bone bed as containing one or more species within a geological layer.
Scientists and volunteers have gently pried fossilized teeth, vertebrae and scales belonging to a variety of dinosaur species from the iron-rich bone bed in Laurel since 2018.
Paleontologist J.P. Hodnett, a program coordinator for the park, was among the group that initially discovered the tibia during a dig on April 22. He believes it belonged to an Acrocanthosaurus, making it the largest therapod fossil discovered in eastern North America.
“This is something paleontologists pray for,” Hodnett said. “To find them [bones] in a concentration like this is fantastic.”
The fossils will be cleaned, examined and cataloged into the museum system for the Prince George’s County Department of Parks and Recreation.
While dinosaur fossils are considered exceptionally rare in the eastern United States, the Dinosaur Park in Laurel has been considered one of the most important dig sites east of the Mississippi River.
Ancient channels of water flowing into the Atlantic Ocean likely swept the bones and other debris, like fossilized wood, depositing them in an area known as the Arundel clays. The land is rich in iron ore and attracted mining operations in the 1800s and 1900s.
Black miners working in open pit mines discovered Maryland’s first dinosaur fossils in 1858. Although the region’s iron furnaces have long since cooled, interest in the site increased in the 1980s.
In 2009, the Maryland-National Capital Park and Planning Commission opened the park to the public, allowing visitors to dig alongside experts. Hodnett used to joke the site should be renamed “Cretaceous Tree Park” because fossils discovered there often turned out to be the remains of ancient vegetation.
Hodnett and other scientists gathered at the aptly-named Dinosaur Park on Wednesday to present their findings publicly. The discoveries, they said, could help humans gain insights into the diversity of animals and plants during a crucial time in the planet’s geological history.
“Typically, only one or two bones are found at a time, so this new discovery of a bonebed of fossils is extremely important,” said Matthew Carrano, a paleontologist with the Smithsonian, in a news release. “It is certainly the most significant collection of dinosaur bones discovered along the eastern seaboard in the last hundred years.”
The discovery is also likely to attract a bevy of visitors and volunteers to the park, where the public can excavate the orange and black patches of soil alongside experts.
Staff often tell visitors to keep their eyes peeled for anything small, ranging in size from a pinky to a thumbnail, that doesn’t seem to fit in with its surroundings. Dinosaur bone encased in rock for millions of years may take on a blueish hue when exposed to oxygen. Some of the best fossilized teeth have been found by children, Hodnett said.
“They have sharper eyes and are closer to the ground,” he said.
Madison Mateo was volunteering at the site when the tibia was unearthed. The 21-year-old, who is studying paleontology at George Mason University, excitedly showed off photos of the rock-encased bones to her parents.
“When we began to speculate, I started to get more excited,” Mateo said.
After Mateo’s classes wrapped up the following day, she rushed back to the site to be a part of the action.
The scientific community’s knowledge of dinosaurs in the eastern United States is lacking, said Thomas R. Holtz Jr., a paleontologist working for the University of Maryland’s Department of Geology.
Holtz, who verified the therapod discovery in the park, said a new bone bed could prove to be extremely important — especially if it produces a complete skeleton rather than fragments.
The bed is located at the base of a rocky hill within the park, meaning scientists will have to dig deeper into the iron-rich shelf to learn if more dinosaurs are buried beneath.
“Chances are looking really good,” Holtz said. “There are more discoveries to come.”