Newly Discovered Dinosaur Had a Unique Weaponized Tail

A newly found ankylosaur species defended itself against predators using a tail weapon unlike anything seen before in the fossil record. Indeed, the greatest analog dinosaur describers could discover was the Mesoamerican battle club, the macuahuitl, in an attempt to describe it. 

The benefits and drawbacks of this slicing blade in comparison to the spikes and maces evolved by other armored dinosaurs are unknown, but the finding demonstrates that Gondwanan Cretaceous animals need the same level of protection as their northern hemisphere counterparts.

Faced with the deadly carnivores of the time, many herbivorous dinosaurs developed tails that could do major injury to the shins and perhaps the soft underbelly of anything that tried to eat them. Some people may have used them in mating battles with their own species.

Paleontologists named the creature “the thagomizer” after a Gary Larson cartoon after failing to come up with a more scientific name. A new late Cretaceous ankylosaur from Chile has been discovered, and its defining characteristic is its thagomizer, which even the paper’s headline characterizes as “bizarre.”

The finding is so unusual from everything else that it requires its own genus, which the scientists have named Stegouros, despite the fact that it has nothing to do with the renowned Stegosauruses. The name Stegouros originates from the Greek words for “roof” and “tail,” and it lived 80 million years later and on the opposite side of the planet from its namesake. Elengassen is the scientific name for this species.

Only one Stegouros fossil has discovered, which is a stark contrast to the ubiquitous Stegosaurus, however, it is nearly complete. It was thought to be fully developed at 180-200 cm (6-7 foot) in length, tail included. For those unfamiliar with ancient Aztec armament, the tail was quite short by armored dinosaur standards, ending in seven pairs of flat bone deposits that formed a configuration similar to a fern frond. It is likely capable of slicing through any imagined dangers.

S. elengassen possessed a skull and teeth that were comparable to those of other ankylosaurs, including those found in the northern hemisphere. The remainder of its body, on the other hand, appears to be a throwback to older periods, with certain traits that resemble stegosauruses.

S. elengassen was discovered in a strata dated between 74.9 and 71.7 million years old in Magellanes, Chile. At the time, the location was a delta, and many dinosaurs and other creatures were stranded there. 

As part of the supercontinent Gondwana, South America was still connected to Antarctica and Australia at the time. The bigger Antarctopelta and Australia’s Kunbarrasaurus appear to be its closest cousins, although Stegouros differed from both in key ways. 

To unite them, the authors propose a new group termed Parankylosauria (“next to the ankylosaurs”). “Many of the ‘genuine’ ankylosaurs that existed in the middle Jurassic, around 165 million years ago, are missing from the Parankylosauria. As a result, the origins of Parankylosauria must be very old, dating back before that time, according to Dr. Alexander Vargas of the University of Chile.

The authors continue to assume that ankylosaurs were less abundant in the southern hemisphere than in the north, but our limited understanding of Gondwana species reflects the amount of research done there. Stegouros is the fourth dinosaur to discover in Chile in the last 10 years. Although they were not abundant, the fact that southern hemisphere ankylosaurs constituted a line that dated back over 100 million years shows that animal kingdom tanks would still exist today if not for an annoying asteroid.