Fossils reveal new species of dog-sized dinosaur


Stegosaurus sculpture by paleoartist Lucas Jaymez. (Image courtesy of Alexander Vargas)

The fossils found in Chile come from a strange dog-sized dinosaur species that had a unique sharp-tailed weapon, scientists reported Wednesday.

Some dinosaurs had pointed tails that they could use as stab weapons and others had tails with clubs. The new species, described in a study in the journal Nature, is something never seen before on any animal: seven pairs of “blades” arranged laterally like a sharp weapon used by ancient Aztec warriors, senior author Alex said. Vargas.

“It’s a really unusual weapon,” said Vargas, a paleontologist from the University of Chile. “Prehistoric animal books for kids need to be updated and put that weird tail in there.… That sounds crazy.”

The plant-eating creature had a combination of traits from different species that initially sent paleontologists down the wrong path. The rear end, including its tail weapon, resembled a Stegosaurus, so the researchers named it Stegouros Elengassen.

After Vargas and his team examined the skull pieces and performed five different DNA analyzes, they concluded that it was only remotely related to the Stegosaurus. Instead, it was a rare member of the southern hemisphere of the chariot ankylosaurus dinosaur family. (Although the name Stegosaurus has stuck and could be easily confused with the more well-known Stegosaurus.)

Vargas called it “the lost family branch of the ankylosaurus”.

The fossil is around 72 to 75 million years old and appears to be an adult based on the fusion of the bones, Vargas said. He was found with his front end flat on his stomach and the rear end tilted to a lower level, almost as if caught in quicksand, Vargas said.


Stegosaurus sculpture by paleoartist Lucas Jaymez. (Image courtesy of Alexander Vargas)

From bird’s muzzle to tail tip, the stegouros stretched about six feet (two meters) but only ascended to the thighs of humans, Vargas said.

The tail was likely intended for defense against large predators, which were also likely deactivated by armor-like bones that protruded and made the stegouros “chewy,” Vargas said.

Not only is it “a really weird tail,” but it comes from the far south of Chile, “a region that has never produced these types of animals before,” said Kristi Curry Rogers, a biologist at Macalester College. , which was not part of the study. .


Image of Stegosaurus created by paleoartist Mauricio Alvarez. (Photo courtesy of Alexander Vargas)

“We’re only scratching the surface when it comes to a comprehensive understanding of dinosaur diversity,” Rogers said. “Stegourus reminds us that if we look in the right places at the right time, there is so much more to discover.”


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