In the Argentine province of Neuquén, in the north of the Patagonia, they lived at least 35 species of dinosaurs. The last to be discovered has been the Bajadasaurus pronuspinax, a hervíboro giant, of about nine meters in length, with enormous thorns in the neck and the back, according to the finding published on Monday in the scientific journal Scientific Reports.
Of the family of the dicreosáuridos, distinguished by the thorns that have as continuation of their vertebrae, the Bajadasaurus pronuspinax It was a quadruped that spent much of its time feeding on plants from the ground while the eye sockets, close to the roof of the skull, allowed it to control what was happening in its environment. Its name contains a double allusion: on the one hand, the town where it was found in 2013, Bajada Colorada; on the other, the long spines inclined forward that characterize it.
"We believe that the long and pointed spines on the neck and back should serve to deter potential predators, but the spines should have been protected by a hornlike keratin case, similar to the horns of many mammals, such as goats, antelopes, they have a heart of bone coated with keratin, "says Pablo Gallina, assistant researcher at Conicet in the Azara Foundation and the Maimónides University and first author of the scientific work. If they had not been protected, they would have broken the first blow.
Other less probable hypotheses are that the spines would have been a kind of candle to regulate body temperature, that they would form a display crest that would give them greater sexual attraction or that would help to sustain fleshy humps among them to store reserves.
"The importance of this study lies, among other things, in that it allows us to know a little more about the dinosaurs that inhabited the area of North Patagonia long before the reign that exerted during the Upper Cretaceous groups of dinosaurs such as the titanosaur sauropods or theropods abelisaurios, on which we know much more, it is with this objective that since 2010 we have been exploring the area of Bajada Colorada where we find rocks 140 million years ago ", underlines Gallina.
The bones of the new species were discovered in 2013. 80% of the skull was recovered, the best preserved worldwide for a dicreosaurid dinosaur, the first vertebrae of the neck and one of the middle part. By studying the teeth and the jaw, 30 centimeters long, paleontologists concluded that this dinosaur spent many hours tearing small plants.
At that time, Argentine Patagonia was very different from what it is today. The Andean mountain range did not exist yet and the climate was much warmer. "It was a fluvial environment, with vegetation adapted to high temperatures and also to periods of drought," the paleontologist describes. Ferns, equisetuses and conifers in the form of shrubs would have been part of the diet of the Bajadasaurus pronuspinax.
Since no fossil remains of the lower extremities can be found, it is not possible to determine the approximate weight of this dicerosáurid, the fourth of this family found in Argentina. His closest relatives are the Amargasaurus cazaui, a species that lived in the area some 15 million years after the Bajadasaurus and the Pilmatueia, who lived in the Lower Cretaceous.
The Bajadasaurus joins the nearly 250 species of dinosaurs found so far in Argentina. Although the findings are spread throughout much of the country, the province of Neuquén has the largest number, so the region that has earned it is known as the Jurassic Park of the Southern Hemisphere.