Paleontologists made the first 3D reconstruction of the hard scales of a prehistoric reptile that ‘overlaps like roof tiles’.
The British team used CT scans to map the heavy body armor of an aetosaurus, a prehistoric reptile that lived 225 million years ago based on Scottish fossils.
The etosaurs were heavily armored reptiles that lived in North and South America, Europe, Asia and Africa and resembled the crocodiles of today.
The rectangular armor of the old land-based herbivore protected it from carnivorous predators.
Skeleton of Stagonolepis, the Scottish aetosaurus, with tough ‘roof tiles’ like scales that helped protect them from predators
WHAT WERE THE ATOSAURS?
Atosuars were herbivores that roamed the world.
They lived in the Late Trias period – between 237 million and 201.3 million years ago.
They had long, heavy bodies such as modern crocodiles.
Aetosaurs were fourfold, which means that they walked four feet.
Their skulls were short and their teeth were small and leaf-shaped.
They had scoop-like blunt noses – meaning they were stupid and turned up at the end.
These distinctive muzzles were suitable for digging or searching for roots, tubers or insects
Evidence of the presence of aetosaurs is found in every continent except Australia and Antarctica.
The new 3D scans show part of the tough and dimple surface that covered the tail of the aetosaurus.
Aetosaurs were first identified from an Elgin specimen in 1844, but at the time it was thought that it was a giant fish due to its scale-like exterior.
“The first one showed a number of rectangular dishes arranged in a closely overlapping, regular pattern, and it was called Stagonolepis, which means” drop-shaped dish, “said Emily Keeble, a graduate of paleontology at the University of Bristol.
“What was identified as giant fish scales are actually armor plates, or osteoderms, made from bone plates and embedded in the skin, just like in modern crocodiles.”
These osteoderms – bone-like structures in the form of scales or plates – are the hard overlapping tiles that formed the protective exterior of the aetosaurus.
“Swirls of the tail have been preserved in the ring of osteoderms, and these show that the specimens were only slightly squeezed out during the preservation process,” Keeble said.
“We could also see how the osteoderms overlap each other like roof tiles, the front osteoderm slightly overlapping the back.”
Osteoderms covered the entire body of the aetosaurus, even over the fleshy parts of the arms and legs.
This body armor, completely wrapped around aetosaurs, served as a defense against predators, including the carnivorous rauisuchians and ornithosuchids.
Both groups had fierce teeth with a striped knife the size of a human finger.
One of the two tail monsters of Stagonolepis robertsoni – an extinct genus of stagonolepid aetosaur
The second fossil specimen, with ‘internal impressions of the caudal osteoderms’
The researchers have scanned two fossil fragments of an aetosaurus tail, which may have been part of the same single creature.
Each specimen shows a full circle of osteoderms around the tail – two above, two below and two on each side.
“They were connected with connective tissue so that the armor was generally flexible, but tough, and could probably protect the animal from the fierce predators of its time,” Keeble said.
The articulated skeletons of 22 etosaurs discovered near Stuttgart, Germany. Aetosaurus remains were considered fish scales in the 19th century
The fossilized aetosaurus samples were collected in 2018 in a sandstone quarry near Elgin, in the north-east of Scotland.
The scanned specimens were of the Stagonolepis robertsoni species – a type of aetosaurus – that was first described by the Swiss biologist Louis Agassiz.
Agassiz mistakenly assumed it was a fish based on drawings of the skin at the bottom of the creature.
This was later corrected by the legendary English anthropologist Thomas Henry Huxley, who reclassified Stagonolepis as a reptile under the crocodilia order.
“The new work also sheds light on how imaging can be used in skin armor research,” the University of Bristol team said in the Scottish Journal of Geology.
“The next steps are to enlarge our library of CT data for aetosaurs.”
An automated tomography (CT) scan is a non-invasive method to study fossilized remains, using x-rays and a computer to make detailed images.