Washington, May 20 (ANI): The discovery of two new skeletons has helped scientists reveal what the reptile Typothorax looked like.
Typothorax is one of the last large herbivores to evolve in the Late Triassic, before dinosaurs would come to dominate the planet.
Reminiscent of giant armadillos, aetosaurs were widespread during Late Triassic times (230 - 200 million years ago).
The largest species of aetosaur grew up to 5 meters long, although the two new specimens, representing a species called Typothorax coccinarum, were smaller growing up to 2.5 meters long.
All were covered by a protective armour of overlapping bony plates, but some species sported massive spikes protecting the neck region - an additional deterrent to any hungry predator.
Dr. Andy Heckert, the lead author of the study and a geology professor at Appalachian State University, regards Typothorax as an "animal designed by a committee combining a crocodile with a cow and armadillo."
Heckert said: "We now know that some previously established ideas about these animals were mistaken.
"For the first time we can get a realistic estimate of the size of these animals, and at only 2.5m [~7 feet) and about 100kg (225 lb) they are not as large as previously thought. We also know that some of the bony spikes that were thought to run down the sides of the armour actually surrounded the cloaca."
The new specimens show that the body was completely enclosed in bony armour even to the extent of having a series of tiny overlapping plates extending down each leg, and onto the hands and feet.
The front limbs apparently sprawled, but the hind limbs were much larger and upright.
Heckert said "one really interesting feature" of the animal's skeleton is its front half, which "is so slender we probably would have thought it belonged to a juvenile if it weren't articulated to the rest."
The new specimens are also providing exciting new information about the way these animals moved.
Fossil skeletons with complete hands and feet are so rarely preserved that it is very difficult to confidently match a skeleton to the maker of any particular trackway.
However, the exquisitely preserved feet in the new specimens demonstrate for the first time that trackways known as Brachychirotherium were almost certainly made by aetosaurs.
Another member of the team Dr. Spencer Lucas, curator at the New Mexico Museum of Natural History, said: "Brachychirotherium tracks are known from various localities around the world, and they are an almost perfect match to the arrangement of bones in the aetosaur foot.
"We now know that the front legs of aetosaurs sprawled to the sides, but their back legs were more robust and pillar-like."
With their short and stubby necks, blunt-nosed skulls, and small leaf-shaped teeth, these distant relatives of crocodiles may also have grubbed around in the soil looking for succulent roots.
Both specimens were found by volunteers at the New Mexico Museum of Natural History and Science.
Lucas said: "The important contribution of amateurs to our science cannot be underestimated.
"As the Badlands erode we look forward to many more exciting new finds that will contribute to our understanding of the world at this important time in its history" The study has appeared in the Journal of Vertebrate Paleontology. (ANI)