Researchers at the Johns Hopkins University School of Medicine have, after years of study, published a description of the fossil of an armoured dinosaur hatchling, which happens to be the youngest nodausor ever discovered.
The discovery of the dinausor fossil also led to the creation of a new genus and species that lived 110 million years ago during the early Cretaceous Era, with the findings published in the Journal of Paleontology.
While Nodosaurs fossils have previously been found in different countries, it is the first time one was found in the United States.
The fossil was originally discovered in 1997 by an amateur dinosaur fossil hunter called Ray Stanford who identified it as a nodosaur and decided to contact David Weishampel, a palaeontologist and a professor of anatomy at the Johns Hopkins University School of Medicine, to have the fossil examined.
A team of scientists led by Weishampel then established the fossil was a nodosaur as a distinctive pattern of bumps and grooves was found on the skull and they did a computer analysis of the skull shape, comparing its proportions to those of ten skulls from different species of ankylosaurs, the group that contains nodosaurs.
Following results of the computer analysis the team found that while the fossil found was closely related to some of the nodosaur species, it also had a much shorter snout overall.
After making a series of comparative measurements the scientists decided to name the new species Propanoplosaurus marylandicus.
In addition to being the youngest nodosaur ever found, it is the first hatchling of any dinosaur species ever recovered in the eastern United States, according to Weishampel
"Now we can learn about the development of limbs and the development of skulls early on in a dinosaur's life," says David Weishampel
"The very small size also reveals that there was a nearby nesting area or rookery, since it couldn't have wandered far from where it hatched. We have the opportunity to find out about dinosaur parenting and reproductive biology, as well as more about the lives of Maryland dinosaurs in general, "he added.
Weishampel also explained he managed to determine the dinosaur's age at time of death by analysing the degree of development and articulation capability of the ends of the bones, as well as deducing whether the bones themselves were porous, as young bones would not be fully solid, the science daily reports.
The body fossil was only 13 cm long, while adult nodosaurs are estimated to have been 20 to 30 feet long.
Weishampel also used the position and quality of the fossil to gather information about the dinosaur's death and preservation, deducing the animal died by drowning, and became buried by sediment in the stream.
The team also says they believe the dinosaur was a hatchling, rather than an embryo, because it was able to walk independently.
"We didn't know much about hatchling nodosaurs at all prior to this discovery," says Weishampel. "And this is certainly enough to motivate more searches for dinosaurs in Maryland, along with more analysis of Maryland dinosaurs."