It’s not every day that you come across a dinosaur that uses a completely unique weapon to defend itself from predators. Chilean researchers announced the discovery of a new species of ankylosaur. A family of dinosaurs known for their heavy armour, from subantarctic Chile in a study published Wednesday in Nature. The dinosaurs had a battle-axe for a tail.
The animal, named Stegouros elengassen, provides new information about the origins of these tank-like dinosaurs. As well as a strange, bony tail shaped, battle-axe like an Aztec warrior’s club. Alexander Vargas is a professor at the University of Chile and a co-author of the study. He says, “It’s lacking most of the traits we’d expect from an ankylosaur. And has a completely different battle-axe tail weapon which shows there’s something very idiosyncratic happening here in South America.”
Ankylosaurs developed hides covered in bone deposits called osteoderms
However, Ankylosaurs of various types once roamed in large numbers across Laurasia. It is the northern supercontinent that once included North America and Asia. As a result even in a group of animals known for their inventive defence strategies, the ankylosaur family stands out. Ankylosaurs developed hides covered in bone deposits called osteoderms. It formed lattices of tooth-breaking armour after splitting from their closest relatives, the stegosaurs, in the mid-Jurassic. The most famous ankylosaur evolved shin-shattering tail clubs, similar to ancient warriors’ maces.
Since these are thought to be the earliest members of the family, the origins and early evolution of the family remains a mystery. A team of palaeontologists from the University of Texas discovered a set of bones in the frigid, wind-blasted valley of Ro Las Chinas. It is located on Chile’s southernmost tip, in February 2018. Despite its intimidating nature, the site is a beacon for palaeontologists: Dr Vargas has spent the last decade dating rocks and looking for fossil hotspots there with researchers including Marcelo Leppe from the Chilean Antarctic Institute.
When the Texas palaeontologists informed Dr Vargas and Dr Leppe of the discovery, there were only five days left in the field season. They hauled the block of fossils downhill to the campsite at night, in the bitter cold. One person suffered a sprained ankle, while another broke a rib. Many people came dangerously close to hypothermia. But what came out of the chopping block was well worth it. Preparation revealed an ankylosaur with an unusually complete skeleton: 80 per cent of a skeleton, including a largely articulated back half, as well as vertebrae, shoulders, forelimbs, and skull scraps.