The new predatory dinosaur Tratayenia rosalesi crosses a stream in what is today Patagonia, Argentina about 85 million years ago.
Although many new dinosaur species have been discovered in recent decades, entire groups of these animals are still mysterious. One of them is the Megaraptoridae, a shadowy group of predators that terrorized South America and Australia during the middle and late Cretaceous period ̵
According to study director Juan Porfiri from the Museo de Ciencias Naturales of the Universidad Nacional del Comahue in Neuquén, "When Diego told us about his find, we quickly got permission from the Provincial Patrimonio Cultural de Neuquén to look after the site went missing and the bones dug up, we were very excited because we thought we might have a megaraptoride. "
Study co-author Domenica dos Santos, also from the Museo de Ciencias Naturales of the Universidad Nacional del Comahue, says," There are not many megaraptorides known, so we thought the new fossil would provide vital information about these enigmatic robbers. " He adds his co-author Rubén Juárez Valieri of the Museo Provincial Carlos Ameghino in Cipolletti, Argentina: "Patagonian discoveries like Tratayenia expand our knowledge of the spectacular but still mysterious dinosaurs of the southern hemisphere."
Tratayenia is identified by many vertebrae and all vertebral bodies of the hip, as well as ribs and parts of the pelvis. Despite the skeletal incompleteness, the bones have unique properties that show they belong to a new species. "The vertebrae of Tratayenia are about as beautiful as dinosaur fossils, and they have some weird features, we want them to have more of them, but what we have is great," says study co-director Matt Lamanna Carnegie Museum of Natural History in Pittsburgh
Tratayenia is the first member of the Megaraptoridae that receives the complete series of hip vertebrae, thus providing an insight into the anatomy of this part of the skeleton in this little known cretaceous carnivore. The new creature may also be the geologically youngest megaraptoroid ever found anywhere in the world, demonstrating that these predators survived until at least 85 million years ago and approached the end of the era of dinosaurs.
Thanks to discoveries like Tratayenia, paleontologists are closer than ever to understanding what Megaraptorids looked like and how they behaved. These dinosaurs had proportionately long, low skulls lined with many sharp serrated teeth; Bones full of air holes like those of their modern relatives, birds; and most conspicuously, long, powerfully muscular forelegs tipped with gigantic claws on the innermost two fingers of each hand. Megaraptorids grew to over nine meters in length and were the largest, deadliest predators in southern South America about 95 to 85 million years ago. They used their enormous hand claws to catch and subdue prey, including other dinosaurs. Lamanna says, "Megaraptoroid claws are the stuff of nightmares – razor-sharp meat hooks more than a foot long – Wolverine of the X-Men has none of these guys."
Scientists have learned a lot about megaraptorids. For one thing, their evolutionary relationships with other carnivorous dinosaurs are poorly understood, with some scientists arguing that megaraptorids are related to even larger carnivores of the southern hemisphere such as Carcharodontosaurus and Giganotosaurus, while others claim that Megaraptorides are close relatives of T. rex. Although Tratayenia does not help solving this particular puzzle, an answer might be in sight. According to Porfiri, "Tratayenia is just one of many exciting megaraptorid fossils found in recent years, and once these specimens have been studied, many questions about these enigmatic flesh eaters can finally be answered."
New dinosaur species could give clues to the evolutionary origin of megaraptorids
Juan D. Porfiriet al. A new megaraptoran theropod dinosaur from the Upper Cretaceous Bajo de la Carpa Formation in northwestern Patagonia, Cretaceous Research (2018). DOI: 10.1016 / j.cretres.2018.03.014