The fossil of an armored dinosaur hatchling – discovered by an amateur fossil hunter in College Park, Maryland – is founder of a new genus and species, Propanoplosaurus marylandicus, which lived approximately 110 million years ago during the Early Cretaceous era.
The baby dinosaur is the youngest nodosaur ever found and the first hatchling of any dinosaur species ever recovered in the eastern United States, according to David Weishampel, a professor of anatomy at Johns Hopkins University School of Medicine.
Researchers describe the new discovery in a paper published in the September 9, 2011, issue of the Journal of Paleontology.
Nodosaurs have been found in diverse locations worldwide, but they’ve rarely been found in the United States. Weishampel said:
Now we can learn about the development of limbs and the development of skulls early on in a dinosaur’s life. 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.
Ray Stanford, a dinosaur tracker who often spent time looking for fossils close to his home, discovered the fossil in 1997 when he was searching a creek bed after an extensive flood.
Stanford identified it as a nodosaur and called Weishampel, who is also a paleontologist. Weishampel and his colleagues established the fossil’s identity as a nodosaur by identifying a pattern of bumps and grooves on the skull.
Next, 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. They found that this dinosaur was closely related to some of the nodosaur species, although it had a shorter snout overall than the others. Comparative measurements enabled them to designate a new species.
The site of Stanford’s discovery had originally been a flood plain, where Weishampel says the dinosaur drowned. Cleaning the fossil revealed a hatchling nodosaur on its back, much of its body imprinted along with the top of the skull. Weishampel determined the dinosaur’s age at time of death by analyzing the degree of development and articulation at the ends of the bones, as well as deducing whether the bones themselves were porous. Young bones would not be fully solid.
Size was also a clue: the body in the tiny fossil was only 13 cm long, just shorter than the length of a dollar bill. Adult nodosaurs were likely 20 to 30 feet long (up to nearly 10 meters). Weishampel also used the position and quality of the fossil to deduce the dinosaur’s method of death and preservation: drowning, then burial by stream sediment.
Eggshells have never been found preserved in the vicinity, and by the layout of the bones and the size of some very small nodosaur footprints nearby, Weishampel came to believe that the dinosaur was a hatchling, rather than an embryo, because it was able to walk.
We didn’t know much about hatchling nodosaurs at all prior to this discovery. And this is certainly enough to motivate more searches for dinosaurs in Maryland, along with more analysis of Maryland dinosaurs.
Stanford has donated the hatchling nodosaur to the Smithsonian’s National Museum of Natural History, where it is now on display to the public and available for research.
Bottom line: Fossil hunter Ray Stanford discovered the first hatchling dinosaur ever found in the eastern U.S. – described by Johns Hopkins University School of Medicine researchers in the September 9, 2011, issue of Journal of Paleontology. It is the youngest nodosaur ever found and is the founder of a new genus and species – Propanoplosaurus marylandicus, according to anatomist and paleontologist David Weishampel.
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