Sword-a-saurus? New fossil slashes through dinosaur history

Stegouros was an ankylosaur with a flat, sharp tail instead of the usual bony club or long spikes
fossil An artist's reconstruction of the amazing Stegouros. (Lucas Jaymez)

Ankylosaurs are famous for being the tanks of the dinosaur world.

These ancient armoured beasties had backs made of dozens of firm, bony plates, often with rows of spikes lining the sides. The impressive ensemble was then all capped off by a lethal tail that finished in a heavy club. One well-placed whack with that weapon would've been enough to smash the leg bone of any predator brave enough to attack it. You did not want to mess with Ankylosaur!

A few ankylosaur species have been found with spiked tails instead—another nasty adaptation predators would've been keen to avoid! And now a brand new fossil in Chile has shown yet another variation in ankylosaur arsenals.

Meet Stegouros—the dinosaur with a sword for a tail!

Slicing through history

According to an interview in Live Science with paleontologist Alexander Vargas, this dino's tail would've looked like "an Aztec sword". Vargas, who works in the Department of Biology at the University of Chile, is a lead researcher on the project. He said that the tail was extremely unique because it was so flat.

The edges of the 'sword's blade' were made of many thin, sharp plates. Think a group of tiles laid flat along the sides of the tail. In fact, the dinosaur's name means 'roof tail', a reference to those bony tiles. In the end, this made the tail look a little like a broad palm frond, or leaf.

You can see what the fossil looks like in the short video below.

Its own path

Though the tail is cool on its own, this fossil is a special find for other reasons, too. For starters, it's nearly 80 percent complete, which is a remarkably high number for a fossil of a dinosaur—many dinosaurs are known from fossils that are only 5 to 10 percent of the actual skeleton.

It is also special because of where it was found—South America. Most other ankylosaurs have been found in the Northern Hemisphere. But Stegouros—which lived about 74 million years ago in the Cretaceous Period—came from a time long after the supercontinent of Pangaea had broken up. This means that it was a species that evolved separately from the northern ankylosaurs. This fossil is a window into a whole other dino world, one where the clubs were replaced by swords. Amazing!

Are there more such species to be found? Almost certainly! It is a wonderful reminder that for all that we know about dinosaurs and their habitats, there is so much more to discover. Who's ready to become a paleontologist?

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  1. Dinosaurs are awesome and I am amazed that they found a new species of dino. It looks like it could cut through anything with it’s tail. WOW!!!!! 😀 🙂 😮 😆 🙂

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