Home Madrid university The skeleton of Abditosaurus kuehnei is the most complete titanosaur fossil discovered to date in Europe

The skeleton of Abditosaurus kuehnei is the most complete titanosaur fossil discovered to date in Europe

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Researchers from the Institut Català de Paleontologia Miquel Crusafont (ICP), the Conca Dellà Museum (MCD), the Universitat Autònoma de Barcelona (UAB), the University of Zaragoza (UNIZAR) and the NOVA University of Lisbon (UNL) have described the new species of titanosaur dinosaur Abditosaurus kuehnei remains excavated at the site of Orcau-1, in the southern Pyrenees (Catalonia, Spain). The 70.5 million year old semi-articulated skeleton is the most complete specimen of this group of herbivorous dinosaurs discovered so far in Europe. What’s more, Abditosaurus is the largest species of titanosaur found in the Ibero-Armorican Island – an ancient region comprising today’s Iberian Peninsula and southern France – representing a senescent individual estimated at 17.5 meters in length with a body mass of 14,000 kg.

The size of this giant is one of the most surprising facts for researchers. “Late Cretaceous titanosaurs from Europe tend to be small to medium-sized due to their evolution in island conditions,” explained Bernat Vila, a paleontologist at ICP who is leading the research. In the Upper Cretaceous (between 83 and 66 million years ago), Europe was a vast archipelago made up of dozens of islands. Species that have evolved there tend to be relatively small or even dwarf compared to their relatives living in vast landmasses, mainly due to the limitation of food resources in the islands. “This is a recurring phenomenon in the history of life on Earth, we have several examples around the world in the fossil record of this evolutionary trend. This is why we were amazed by the large dimensions of this specimen” , Vila said.

Fieldwork conducted over several decades unearthed 53 skeletal elements of the specimen. These include several teeth, vertebrae, ribs and limb, scapular and pelvic bones, as well as a semi-articulated fragment of the neck formed by 12 cervical vertebrae. “We were very lucky, it is unusual to find such complete specimens in the Pyrenees due to its turbulent geological history”, explains Àngel Galobart, ICP researcher and director of the Conca Dellà museum (Isona, Catalonia).

The excavation of the pass in 2014 was a technical challenge. Once prepared for extraction, the cervix was encased in a large block of polyurethane foam, becoming one of the largest sheaths ever discovered in Europe.

The history of the research that led to the description of the new species dates back to 1954, when the German paleontologist Walter Kühne collected the first remains and sent them to Madrid. The site fell into oblivion until 1986, when other remains began to be excavated until a great storm forced the cancellation of the excavations. Subsequently, fieldwork at the site again fell into oblivion until an ICP paleontologist resumed systematic excavations at Orcau-1. The story of this discovery was featured in the 2017 documentary “The Last Giant in Europe”. The generic name Abditosaurus means ‘forgotten reptile’ and the specific epithet kuehnei is a tribute to its discoverer.

A migrating dinosaur

In their article published in Nature ecology and evolutionthe researchers conclude that Abditosaurus belongs to a group of saltasaur titanosaurs from South America and Africa, different from the rest of the European titanosaurs which are characterized by a smaller size. These authors hypothesize that the Abditosaurus the lineage reached the Ibero-Armorican island taking advantage of a global drop in sea level that reactivated ancient migration routes between Africa and Europe.

“Other evidence supports the migration hypothesis,” says Albert Sellés, ICP paleontologist and co-author of the paper. “At the same site, we found eggshells of dinosaur species known to have inhabited Gondwana, the southernmost continent.”

This new discovery is a major advance in understanding the evolution of sauropod dinosaurs during the late Cretaceous and brings a new perspective to the phylogenetic and paleobiogeographic puzzle of sauropods during the last 15 million years before their extinction.

Besides Vila, Sellés and Galobart, Novella Razzolini (Institut Català de Paleontologia Miquel Crusafont and Conca Dellà Museum), Miguel Moreno (Museu de Lurinhã and NOVA University of Lisbon), Iñaki Canudo (Aragosaurus-IUCA Group, University of Zaragoza) and Alejandro Gil (Universitat Autònoma de Barcelona) participated in this study.

“During the Jurassic and Cretaceous, the Iberian Peninsula was the connecting point between Eurasia, Africa and North America. Studying how Abditosaurus relates to the fauna of these continents helps us to understand when there were links between them and when they became isolated”, explains Miguel Moreno, researcher at the Museu de Lurinhã and the NOVA University of Lisbon who carried out the paleobiogeographic study.

The great herbivores of the Cretaceous

Titanosaurs are a group of sauropod dinosaurs that become highly diverse and abundant in Cretaceous terrestrial ecosystems. All were quadrupedal and phytophagous. Titanosaurs had a small, pointed skull, with small nail-like teeth used to uproot vegetation. Their body was robust, with forelimbs shorter than hindlimbs and a long neck and tail. Some species sported skin covered in bony plates called osteoderms that may have served as a protective shield or calcium store.

Paleontological sites in the Catalan Pyrenees have provided exceptional dinosaur fossils over the past century. The research is particularly important because its fossil record includes the last vertebrate faunas, including non-avian dinosaurs, that lived in Europe just before the global extinction that took place 66 million years ago.

On the PCI: The Institut Català de Paleontologia Miquel Crusafont (ICP) is a CERCA center (Centres de Recerca de Catalunya, Generalitat de Catalunya) attached to the Universitat Autònoma de Barcelona (UAB) and dedicated to research in paleontology of vertebrates and humans at most high international level, as well as the conservation and dissemination of Catalan paleontological heritage. It is constituted as a public foundation with a board of directors made up of the Government of Catalonia and the UAB.