Bones of the smallest dinosaur in the world found in Burgos

Burgos. The Salas Archaeological and Paleontological Collective (CAS) found at the Vegagete site, near Villanueva de Carazo (Burgos), about 800 bones, corresponding to six individuals, of the “smallest dinosaur in the world”, less than 30 centimeters high.

It is about the Foskeia pelendonum“smallest known” ornithopod species. The name of the new species is a tribute to the Pelendones, a Celtiberian tribe that inhabited the area; It also refers to their unique way of eating, as detailed by the team in a statement sent to Europa Press.

The 800 fossilized bones, “the vast majority fragmented and incomplete,” are in good condition. Its tiny size made research difficult, but it was possible to identify about 350 that belonged to six individuals, from babies to adults, who would form a herd.

From the beginning, researchers at the Salas de los Infantes Dinosaur Museum considered the special characteristics that these fossils presented. In 2013, a definitive boost was given to their study with the arrival of Paul-Émile Dieudonné to Salas, who would carry out his final master’s thesis with these fossils.

Paul-Émile Dieudonné himself, a doctoral student in vertebrate paleontology at the National University of Río Negro (Argentina), has directed the study, for which an international team of researchers was formed made up of members of the Salas de los Infantes Dinosaur Museum, the National University of Córdoba (Argentina), the Federal University of Rio de Janeiro (Brazil), the University of La Laguna (Tenerife), the Royal Belgian Institute of Natural Sciences (Belgium) and the University Free of Brussels (Belgium).

The overall shape of the skull “differs markedly” from other ornithopod dinosaurs, the study notes. “It is very wide in its posterior area and its jaw is very developed to establish powerful chewing muscles. The front teeth are very small and would not be used, while the posterior teeth are relatively large, supporting the chewing process,” the statement adds.

The animal could have compensated for its size and the loss of chewing muscle mass with a new way of chewing to feed on vegetables with a certain hardness. “It is striking that this animal, unlike other species of ornithopods, did not have a rhamphotheca, a horny covering at the anterior end of the skull (which birds have in their beak). Several cranial bones also have very peculiar features.”

Likewise, the femur has “unique” anatomical characteristics, which have been interpreted “as the change in the way they walk throughout their lives: young people were bipedal and adults quadrupedal.” Besides, Foskeia represents a “primitive link in the evolution that led to the rhabdodontids. These lived in the Upper Cretaceous, between 80 and 65 million years ago, but their origin and ancestors were unknown, so they were considered a ghost lineage. The new Burgos species, 125 million years old, fills a gap in knowledge about the evolution of this group of dinosaurs over millions of years,” they add.

The legs of this animal grew very quickly and in the adult they were very slender. “It follows that this animal would not have had great physical resistance to run long distances and thus escape from predators, so it would probably make quick and short runs to safe areas,” they noted.

Its size makes it the smallest ornithopod dinosaur in the world currently known, with a skull 5.5 centimeters long, a body length of between 50 and 60 centimeters and a height that would not exceed 30 centimeters.

The new Burgos dinosaur has represented a “real upheaval” in the knowledge about the evolution of rhabdodontids from the Upper Cretaceous. Its small size was interpreted as a form of dwarfism caused by living on islands where food resources are scarce.

“The small size of Foskeiaof an older age, suggests another hypothesis: in reality the rhabdodontids would have become progressively larger, since the pressure of predators on prey would be lower towards the end of the Cretaceous. Furthermore, the characteristics of Foskeia “suggest that the rhabdodontids of the Late Cretaceous were quadrupeds throughout their lives, and not bipeds as they were usually represented.”

The size of the species indicates that most of the rhabdodontomorphs pending discovery “would also be small, compared to what is known until now.”