Remains of a species of herbivorous dinosaur previously unknown to exist in the Southern Hemisphere have been discovered in the Chilean Patagonia, according to a new study published in the journal Science Advances. The new Gonkoken nanoi species belongs to an ancient lineage of hadrosaurids, a group also known as duck-billed dinosaurs.
In 2013, an expedition from the Chilean Antarctic Institute led by its director, Dr. Marcelo Leppe, discovered fragments of yellowish bones at the bottom of a hillside in the Río de Las Chinas Valley, a nearby area to Torres del Paine, in Chilean Patagonia. This was the beginning of an intense research carried out by the paleontological network of the University of Chile.
The unearthed bones, among other fossils, included skull material, cervical, dorsal, and caudal vertebrae, ribs, arm and leg bones.
After almost a decade of work, the researchers not only managed to identify a new species of dinosaur, but also digitally reconstruct its skeleton, initiating a debate on an evolutionary mystery that its discovery entails.
The new species is a herbivorous animal that lived 72 million years ago in the extreme south of what is now Chile. Measuring up to four meters long, weighing up to a ton and endowed with a duck's beak, it is associated with an ancestral lineage of hadrosaurids. The researchers revealed that Chilean Patagonia served as a refuge for these primitive forms of hadrosaurids.
"The interesting thing is that other species of 'duck-billed' dinosaurs were already known in South America. All those found in Argentine Patagonia had been named, but all of these are within a group or family called hadrosauridae or the true 'duck-billed' dinosaurs, or the 'advanced duck-billed' dinosaurs," said Jhonatan Alarcón-Muñoz, researcher at the paleontological network of the university and lead author of the study.
Previously, scientists suggested that all the species of hadrosaurids found in Latin America evolved from one, which had arrived from North America over 70 million years ago. However, the discovery of this more primitive “duck-billed” species in a more southern area suggests that there was more than one migration from North America.
The study indicated that the ancestors of the Gonkoken arrived before the ancestors of the known hadrosaurids in Argentina and reached further south into regions where hadrosaurids never arrived, surviving there as a relict species, "because when this hadrosaur lived, its relatives already had become extinct in the rest of the world."
Alexander Vargas, director of the Paleontological Network of the University of Chile and one of the authors of the study, noted that "these were slender-looking dinosaurs, which could easily adopt both a bipedal and quadrupedal posture to reach vegetation at height and at ground level." They had large beaks flattened at the end, similar to a duck, but with sharper edges.
"Their tooth batteries with hundreds of teeth are arguably the most complex in vertebrate evolution and were capable of crushing, grinding, and shearing, allowing them to exploit a broad range of plant resources," read the study.
Alarcón-Muñoz explained that the name 'Gonkoken', which means "similar to a duck or a swan," has its origins in the Aónikenk language of native people who inhabited the region where this species was found. As for the term 'nanoi', it was used to honor Mario "Nano" Ulloa, who first found dinosaur bones at Río de las Chinas Valley and provided key logistic help during expeditions.
The scientists highlighted the scientific importance of their finding, noting that the discovery allowed them to learn more about how the ancestors of the known hadrosaurid species looked like.