Found the youngest species of a known Diplodocid, the only one in South America

José Pichel Andrés/DICYT Argentinian scientists have found a new species of Sauropoda dinosaur called Leinkupal laticauda, the only register of the Diplodocid family (Diplodocidae) in South America and the last of them that survived in the world, since the ones of the other continents are older. The work has just been published in the magazine PLOS ONE and talks about a small-sized dinosaur compared to the ones of its race, but with a powerful tail.

In order to follow the lead of this discovery, one has to go back some years, according to information the authors have given to DiCYT. At the end of the nineties, the famous Argentinian paleontologist José Fernando Bonaparte began to emphasize the importance of rocks from the beginning of Cretaceous to understand the history of dinosaurs as well as the geologic formation known as Bajada Colorada, above the middle valley of river Limay, in North Patagonia, where he discovered 130-million-year-old fossils.

Later, one of his apprentices, Sebastián Apesteguía, together with Pablo Gallina, researchers of CONICET of Félix de Azara Foundation, of University of Maimónides, joined together with the paleontology team of Ernesto Bachmann Municipal Museum, of Villa El Chocón (Neuquén) formed by Alejandro Haluza and Juan Canale, in order to explore rocks which had been deposited in the beginning of Cretaceous about 140 million years ago. Curiously, this campaign has been financed partly by Jurassic Foundation, an American foundation made up with the money raised by the movie Jurassic Park.

Extremely damaged materials

When they started working in 2010, they found a site with extremely damaged bones, spoiled by erosion and began working hoping that they could find some in better conditions. The remains found in 2010 and at the 2012 and 2013campaigns accumulated in the fossil preparation lab of Bachmann Museum of Villa El Chocón. When the paleontology lab technicians began to put the pieces together, they were surprised: the materials did not correspond to any of dinosaur groups known until that moment.

Therefore, the study has concluded that it was a new species which was called Leinkupal laticauda. In the Mapudungun language the Mapuche Leinkupal means “family that disappears”, since the discovery corresponds to the last world discovery known of a dinosaur of the Diplodocid family; and laticauda, which, in Latin, means “wide tail”, since this is a very peculiar characteristic of this dinosaur.

The material studied is a dislocated skeleton, mixed together with bones of another dinosaur, that is why they had to carefully analyze the anatomy of the specimen in order to determine which bones belonged to him and which did not. Among the discovered bones, a vertebra of the tail was named as type material, the bearer of the dinosaur’s name, while the rest of the studied specimen is formed by three vertebrae of the neck, one of the back and four more of the tail.

Kinships

The phylogenetic analysis, that is, the kinship relationships, shows that Leinkupal was a well-defined Diplodocidae, of the Diplodocid subgroup, as the known North American Diplodocus or the African Tornieria. Leinkupal is the only register of a Diplodocid in South America.

The Brontosaurs’ history, a common Diplodocidae name, with their extremely large necks and tails, has been written especially in the North Hemisphere. They are the most famous dinosaurs in North America, probably because they have been present in series and movies from The Flintstones to The Colossus, by whose legs the motorcycle passed by in Jurassic Park 2. Their fossils have been found abundantly in rocks of Jurassic Superior in the United States. This was the Diplodocids best moment between 144 and 200 million of years ago. Numerous species inhabited North America, the Iberian Peninsula and an austral continent: Africa, the only register in the South Hemisphere until now and its last sign, because, at the end of Jurassic, they seemed to have been extinguished all around the world.

About 8 or 9 meters of length

The Leinkupal’s 8 or 9 meters are tiny if compared with its relatives of Jurassic in North America, which could have about 20 meters of length. Besides, the discovery of loose teeth at the same place suggests that other Sauropods were also there. The Brachiosaurus are their distant relatives, with their wide snouts, and the Dicraeosaurus, with their bony back, which have been found in Argentina.

In spite of its modest size, its tail was more powerful than its other relatives, the Brontosaurus. The vertebrae of the tail, Leinkupal’s most important characteristic, are very wide and neumatized (with cavities where sacs with air were lodged), where strong muscles were inserted, what allowed them to sway about laterally, in a more noticeable way if compared to other Diplodocids.

The world that separated the Diplodocids

In the area 140-million-year-old rocks appear, known as Bajada Colorada Formation, deposited in a time when the Andes Mountain Range did not exist and the Atlantic Ocean was beginning to insinuate itself, the Neuquén region was immersed by the Pacific Ocean. The dominant dinosaurs were very different from the ones of Superior Cretaceous (Sauropods titanosaurus and Theropods abelisaurus), which would soon become famous in Neuquén. At this point, with the end of the Jurassic and the beginning of the Cretaceous, the world was different. The carnivore dinosaurs were related to the Allosaurus, while the long-neck Sauropods were integrated by different forms that included their big relatives, the Brachiosaurus.

A great part of the evidence shows that the Diplodocids originated in the Jurassic, and that they prospered and evolved in an isolated way after the separation of Pangaea (in north Laurasia and south Gondwana) and the desert formation, as a result characteristic groups of each region originated. From the south, only one from Africa is known and one in Patagonia: Tornieria africana and Leinkupal laticauda.

The original fossil materials of this Sauropod can be found at the Paleontology Museum “Ernesto Bachmann” of Villa El Chocón, Neuquén.

	Bibliography
	A Diplodocid Sauropod Survivor from the Early Cretaceous of South America. Pablo A. Gallina, Sebastián Apesteguía, Alejandro Haluza, Juan I. Canale. PLOS ONE, 2014. DOI: 10.1371/journal.pone.0097128