The baby dinosaur, measuring a mere five inches, likely drowned in a stream.
A hatchling dinosaur representing a new species, Propanoplosaurus marylandicus, was found in Maryland.
The dinosaur is the youngest nodosaur ever found the first hatchling ever recovered in the Eastern United States.
Maryland had a warm, tropical environment during the Early Cretaceous and was home to many dinosaurs.
A five-inch-long baby dinosaur with a short nose, armor and spikes went belly-up and likely drowned in what is now the Washington, D.C. beltway, say scientists, who describe the find as a new species as well as the first hatchling of any dinosaur species ever recovered in the eastern United States.
The tiny dinosaur, Propanoplosaurus marylandicus, is the youngest nodosaur ever found. This group of short-necked, plant-eating dinosaurs reached about 30 feet long when fully grown and had powerful jaws and small teeth.
"Dinosaurs grew up faster than we ever imagined," said Ray Stanford, a Maryland-based dinosaur tracker who was the lead author of a study on the find in the Journal of Paleontology. "We can tell that this little guy was just a hatchling because the bones were elastic and cartilaginous upon death and not ossified."
Stanford found the new 110-million-year-old nodosaur while searching a creek bed in Maryland's Prince George's County after an extensive flood. The area, according to Stanford, was quite a hotbed of dinosaur activity during the Early Cretaceous.
Major predators, such as huge meat-eating Acrocanthosaurus, lived in the region, along with numerous large sauropods, and other plant-eaters like Hypsilophodon and Iguanodon.
"The climate was quite warm and tropical," he said, adding that it was full of lush palm-like trees, such as Cycadophytes members.
The living wasn't always easy for dinosaurs, however, as the little nodosaur proves. Stanford and his team believe the baby dinosaur, which grew to only five inches long, drowned before getting buried by sediment in the stream. They base this on the location and the fact that the dinosaur was preserved on its back. Stanford said dinosaurs that drown exhibit "float and bloat" characteristics shared by this specimen.
Weishampel, a paleontologist and a professor of anatomy at the Johns Hopkins School of Medicine, led a computer analysis of the baby dinosaur's skull, comparing its bumps, grooves and proportions to 10 other species of ankylosaurs, the group that contains nodosaurs.
They determined the dinosaur was closely related to other nodosaurs, but had distinctive features, such as a particularly short snout, which earned its designation as a new species.
"We didn't know much about hatchling nodosaurs at all prior to this discovery," Weishampel was quoted as saying in a press release. "And this is certainly enough to motivate more searches for dinosaurs in Maryland, along with more analysis of Maryland dinosaurs."
Stanford indicated the short-snouted dinosaur, preserved as a natural cast, softens the image of its tougher looking armored parents.
"Babies tend to be cute with their short noses, so this one fits that description," he said. "It also had legs that were disproportionately long for its body, allowing for running."
Amateur collector Stanford donated the hatchling nodosaur to the Smithsonian's National Museum of Natural History, where it is now on display and is also available for additional research.
Stanford hinted that he has many more exciting finds awaiting further analysis. If his predictions hold true, Maryland may be home to the world's biggest pterosaur, some of the most detailed prehistoric mammal tracks ever found, and "wonderful pieces of fossilized dino poop" with associated footprints that reveal possible behavioral traits.