A newly discovered species of ankylosaur protected itself from predators with a tail weapon system that is unlike anything in the paleontological record . Indeed , in an cause to describe it , the skillful comparison dinosaur describers could find was the Mesoamerican war club , themacuahuitl . The reward and disadvantages of this strap sword compared to the spikes and mace develop by other armoured dinosaur stay a secret , but the discovery proves Gondwanan Cretaceous metal money were in need of as much security as their northerly hemisphere vis-a-vis .
Faced with the fearsome predator of the era , many herbivorous dinosaurs institute armor insufficient , developing tails that could do serious equipment casualty to the shins , and maybe subdued underbellies , of anything that tried to eat them . Some may have also establish these useful in felt conflicts with their own specie .
Having failed to develop a more scientific term , paleontologists follow the name “ the thagomizer ” after a Gary Larson animated cartoon . A paper inNaturedescribes a freshly describe late Cretaceous ankylosaur from Chile , whose defining feature is its thagomizer , which even the paper ’s headline call “ bizarre ” .
The discovery is different enough from anything known it needs a new genus , and the authors have called it Stegouros , which bewilderingly has nothing to do with the noted Stegosauruses . The name comes from the Greek words for “ roof ” and “ tail ” ; Stegouros experience 80 million yr later and on the other side of the world from its dear namesake . The mintage name is elengassen .
Only one Stegouros fossil has been regain – another major dividing line to the common Stegosaurus – but that one is almost complete . At 180 - 200 cm ( 6 - 7 foot ) long , bottom included , it is conceive to have been amply spring up .
The tail was comparatively short by the standards of armored dinosaurs and ended in seven pairs of flat bony deposits that work a form somewhat like a fern frond , for those unfamiliar with ancient Aztec munition . It could probably slice deeply into any perceive menace .
S. elengassen had a skull and teeth similar to other ankylosaurus , including the much more common interpreter in the northerly hemisphere . The rest of its body , however , looks like a throwback to earlier time , include some feature film that do indeed resemble stegosaurus .
S. elengassen was bump in a layer dated between 74.9 - 71.7 million years older from Magellanes as the southern top of Chile . The site was a delta at the time in which many dinosaur and other beast were trapped . At the prison term South America was still unite to Antarctica and Australia as part of the supercontinent Gondwana . It ’s nearest know relatives seem to be the largerAntarctopeltaand Australia’sKunbarrasaurus , but Stegouros had several noticeable differences from each . The authors nominate a new clade shout Parankylosauria ( " next to the ankylosaurs " ) to combine these . “ The Parankylosauria lack many features of the ' on-key ' ankylosaurus that were already present in the middle Jurassic , about 165 million years ago . Therefore , the roots of Parankylosauria must be very onetime , before that date ” said Dr Alexander Vargas of the University of Chile say in astatement .
The authors still think ankylosaur were genuinely less common in the southern cerebral hemisphere than in the Frederick North , but our circumscribed cognition of the Gondwana specie also partially reflect the amount of exploration done there . No dinosaurs from Chile were name before 2011 , Stegouros is the fourth in ten years .
Although they may not have been common , the fact the southern hemisphere ankylosaurs represented a stock that stretch back almost 100 million long time suggests tanks of the fauna kingdom might still be around today , were it not for a meddling asteroid .
