An article published in the “Journal of Vertebrate Paleontology” describes a research on a theropod dinosaur that lived in the late Cretaceous period, about 76 million years ago, which was called Rativates evadens. A team of paleontologists led by Bradley McFeeters of Carleton University reexamined a partial skeleton that was attributed to the species Struthiomimus altus concluding that its characteristics are quite different to actually be a different genus.
The fossil bones of Rativates evadens were found in 1934 in the area of today’s Dinosaur Provincial Park in Alberta, Canada. It’s one of the largest deposits of dinosaur fossils in the world and for that reason in 1979 was listed as a UNESCO World Heritage Site. The specimen had an estimated length of about 3.3 meters (11 feet), a height of about 1.5 meters (5 feet) and a weight around 90 kg (200 lbs).
In 1950 the specimen, classified as ROM 1790, was attributed to the species Struthiomimus altus but according to Bradley McFeeters it doesn’t have the key characteristics of that species. For this reason, he and his collaborators who examined the bones recognized not only a different species but also a different genus. Both species belong to the family of Ornithomimosaurs (Ornithomimosauria), also called ostrich-dinosaurs for their appearance in many ways similar to that of their present distant cousins.
The classification of Ornithomimosaurs is complex because often based on partial skeletons, a problem common to various groups of prehistoric animals. In these cases, each new study can bring new answers but also new questions. In this case, the assignment of a skeleton of the species Rativates evadens strengthens the link between the Ornithomimosaurs that lived in today’s Canada and those that lived in today’s Asia.
Theropod dinosaurs were generally carnivores but the similarities of Rativates evadens with ostriches was also given by its beaked mouth with no teeth. For this reason, the paleontologists think they were omnivores feeding on plants, insects and small animals. With its long legs it was a good runner so it could hunt small animals and flee from the large predators that lived in his time, towards the end of the dinosaurs era, such as Tyrannosauridae.
The exams of Rativates evadens’ femur indicate that it was at least eight years old and when it died its size was close to that of an adult. Its mass was just over half of that of an adult Struthiomimus altus, suggesting that there were at least two related species but of different size that lived together in that ancient ecosystem. Claudia Schröder-Adams, co-author of the article, compared that situation to the current coexistence of foxes, coyotes and wolves in some areas.
This research on Rativates evadens shows once again that sometimes you don’t need to find new fossils to discover new species but you have to be sure you’re adequately examined the ones available. The knowledge accumulated in the field of paleontology over the decades and new technologies now allow to conduct better studies to obtain new information about ancient creatures.
