SANTIAGO, Dec 2, 2021 (BSS/AFP) - Chilean paleontologists on Wednesday
presented their findings on a dinosaur discovered three years ago in
Patagonia which they said had a highly unusual tail that has stumped
researchers

  The remains of the Stegouros elengassen were discovered during excavations
in 2018 at Cerro Guido, a site known to harbor numerous fossils, by a team
who believed they were dealing with an already known species of dinosaur
until they examined its tail.

  "That was the main surprise," said Alexander Vargas, one of the
paleontologists. "This structure is absolutely amazing."

  "The tail was covered with seven pairs of osteoderms ... producing a weapon
absolutely different from anything we know in any dinosaur," added the
researcher during a presentation of the discovery at the University of Chile.

  The osteoderms -- structures of bony plaques located in the dermal layers
of the skin - were aligned on either side of the tail, making it resemble a
large fern.

  Paleontologists have discovered 80 percent of the dinosaur's skeleton and
estimate that the animal lived in the area 71 to 74.9 million years ago. It
was about two meters (almost seven feet) long, weighed 150 kilograms (330
pounds) and was a herbivore.

  According to the scientists, who published their research in the journal
Nature, the animal could represent a hitherto unknown lineage of armored
dinosaur never seen in the southern hemisphere but already identified in the
northern part of the continent.

  "We don't know why (the tail) evolved. We do know that within armored
dinosaur groups there seems to be a tendency to independently develop
different osteoderm-based defense mechanisms," said Sergio Soto, another
member of the team.

  The Cerro Guido area, in the Las Chinas valley 3,000 km (1,800 miles) south
of Santiago, stretches for 15 kilometers. Various rock outcrops contain
numerous fossils.

  The finds there allowed the scientists to surmise that present-day America
and Antarctica were close to each other millions of years ago.

  "There is strong evidence that there is a biogeographic link with other
parts of the planet, in this case Antarctica and Australia, because we have
two armored dinosaurs there closely related" to the Stegouros, said Soto.