Chilean paleontologists presented, Wednesday, December 1, the results of their research on the Stegouros elengassen, a dinosaur whose skeleton was discovered almost intact in Patagonia in 2018. It had been unearthed during excavations at Cerro Guido, a site known to harbor many fossils. At first, the team thought they were dealing with an already known type of animal, until they discovered the remains of its tail. “absolutely amazing”.
The latter “was covered with seven pairs of osteoderms (…) producing a weapon absolutely different from anything we know for a dinosaur”, explained Alexander Vargas, one of the paleontologists, during the presentation of the discovery at the University of Chile. These osteoderms, bony plaques located in the dermal layers of the skin, are aligned on either side of the tail and make it look like a large fern.
Paleontologists estimate that the animal lived in the area 71 to 74.9 million years ago. It was about two meters long, weighed 150 kilograms and was herbivorous. According to the scientists, who published their research in the specialized journal Nature, he could be part of a hitherto unknown line of an armored dinosaur never seen in the southern hemisphere but already identified in the north of the continent. “We don’t know why [la queue] has evolved. We know that within armored dinosaur groups there appears to be a tendency to independently develop different osteoderm-based defense mechanisms. “, explained Sergio Soto, another member of the team.
The Cerro Guido area, in the Las Chinas valley 3,000 km south of Santiago, stretches for 15 km. Various rock formations outcrop there, which contain many fossils. It is “a kind of book that allows us to understand the successions of flora and fauna in this place”, explain paleontologists. It also allowed them to discover that present-day America and Antarctica were close millions of years ago. “There is strong evidence that there is a biogeographical link with other parts of the planet, in this case Antarctica and Australia, as we have two closely related armored dinosaurs there.” to Stegouros, said Sergio Soto.