A new dinosaur species was recently discovered in Mongolia. Analysis of the extinct reptile's skeletal structure reveals that while it was of the same taxonomical clade as the T-rex and other bipedal carnivorous dinosaurs, it was also specially adapted for aquatic activities.
The discovery was revealed in an article published in Communications Biology on Thursday.
The dinosaur, which has been named Natovenator polydontus, (Latin for “swimming hunter with many teeth"), was discovered in the Omnogovi Province of Mongolia and is believed to have lived in the upper Cretaceous, a period of time stretching from roughly 100 million years ago to about 66 million years ago.
The specimen discovered was remarkably well preserved by the fossilization process, and hence, distinct features were left intact. Researchers were thusly able to theorize with a great degree of certainty that it was physiologically adapted to a water-based lifestyle.
Natovenator belongs to a category of dinosaurs called theropods, which refers to bipedal, saurischian (lizard-hipped) dinosaurs. This family includes dinosaurs such as tyrannosaurus rex, allosaurus, velociraptor, deinonychus, and many others.
It also, however, includes birds, which are the modern descendants of the Mesozoic theropods. Birds are considered avian theropods and exhibit remarkably similar skeletal structures to the newly discovered Natovenator.
Additionally, researchers have been able to place the new species in the Dromaeosauridae subfamily, Halszkaraptorinae, a family that contains species such as Halszkaraptor, a waterfowl-like theropod dinosaur.
Natovenator polydontus's behavior
The most significant indicator pointing to the dinosaur's aquatic behavior is its ribcage, as its posterolaterally oriented dorsal ribs worked to streamline its body. "Additionally," the article explains, "the widely arched proximal rib shafts reflect a dorsoventrally compressed ribcage like aquatic reptiles."
However, among non-avian theropods, Natovenator is almost entirely unique in that it is thought to have been semi-aquatic. Furthermore, among those aquatic or semi-aquatic theropods that have been discovered, none have the streamlined physiological structure indicated by the ribcage of the Natovenator.
The structure of Natovenator's ribcage, taken with the fact that, according to the study, the dinosaur "exhibits anatomical characteristics very similar to the aquatic adaptations in Halszkaraptor," further solidifies the evidence of its aquatic lifestyle.
The discovery helps to illuminate an evolutionary trajectory taken by ancient theropods and further highlights the similarities between modern birds and their prehistoric counterparts.