Science & Technology

Armored dinosaur species with unique tail weapon discovered in Chile

Santiago, Dec 1 (EFE).- A small armored dinosaur species with a unique weaponized tail has been discovered on the southernmost tip of Chile, where researchers came upon an intact fossil dating back around 74 million years.

That find was made three years ago in Magallanes province in Patagonia and was described in a study published Wednesday in the British scientific journal Nature.

It ranks with the most important finds in Chilean paleontology along with the discovery of Chilesaurus diegosuarezi, a dinosaur described as the missing link between early plant-eaters and carnivorous dinosaurs like Tyrannosaurus rex.

The discovery of the two-meter (6.5-foot) Stegouros elengassen occurred in February 2018 in an inhospitable area near Torres del Paine National Park when a group of paleontologists extracted a block of fossils from a steep hill in the Rio de las Chinas Valley.

The find revealed the existence of a heretofore unknown lineage of armored dinosaurs; of particular interest was the dinosaur’s tail, which was unlike any other documented to date.

The end of the tail had a unique shape that resembles a macuahuitl – a feared, bladed club used by the ancient Aztecs – and clearly alerted paleontologists to the presence of a new species of armored dinosaur.

As the teams chipped away at the block, they found a nearly complete skeleton with a stunning tail weapon – a “flat, frond-like structure formed by seven pairs of laterally projecting osteoderms encasing the distal half of the tail,” according to the abstract of the article published in Nature.

Paleontologist Sergio Soto, a University of Chile doctoral student and the study’s primary author, said the research showed that dinosaur was a transitional ankylosaur, meaning an “evolutionary link between the ankylosaurs (a group of herbivorous dinosaurs that had armor in the form of bony osteoderms) and other older lineages of armored dinosaurs.”

“Stegouros only has some of the features normally found in ankylosaurs, mainly in the cranium, but many others are missing,” Soto said. “It also has some features that are similar to the stegosaurians (and were) inherited from a common ancestor, but that other ankylosaurs lost as they evolved.”

The team from the University of Chile says the find provides insight into the evolution of armored dinosaurs, the record of which has been meager in the Southern Hemisphere.

For his part, paleontologist Alexander Vargas said stegosaurians are among the most recognizable dinosaur species due to their powerful dorsal plates and the pairs of spikes at the end of their tails.

“Advanced ankylosaurs, on the other hand, are famous for their wide backs armored with rows of bony osteoderms and for having a rounded mass of bone at the end of their tails. Clearly the tail weapon of our dinosaur was nothing like the (previously discovered ones),” the scientist said.

The study also concluded that armored dinosaurs are the only lineage of terrestrial vertebrates that independently evolved three radically different types of specialized tail weapons: the paired spikes of the stegosaurians, the bony mass of the advanced ankylosaurs and the macuahuitl of the recently discovered Stegouros elengassen. EFE


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