Researchers from the Aragosaurus-IUCA group of the University of Zaragoza havediscovered the oldest and most complete collection of fossils of sirenians or “sea cows”, 45 million years ago, in the Aragonese Pyrenees. In total, about 550 fossil remains of these vertebrates have been recovered, among which three skulls stand out, one of them in perfect condition. The excavations of the sites, located in the Sobrarbe Geopark, have been directed by the researcher Ainara Badiola.
ThesireniansThey are a group of aquatic and herbivorous mammals or plant eaters, which, together with their appearance, has favored that they are popularly known as “sea cows”. The name sirenios refers to the mermaids of mythology, although their appearance is very different from that described by classical Greek writers, as Christopher Columbus noted in his diary when he saw them for the first time. They have a thick, fusiform body with the pelvic girdle and the limbs, especially the hindquarters, modified with respect to continental mammals. In the past, these marine mammals were abundant and widely distributed from the western Atlantic to the Eurasian-African coasts.
The significance of the discovery of the sirenians of the Geopark is that, in addition to being the most complete and ancient dugongi in Europe, they have been found in the Pyrenean domain, in what wasan arm of the Atlantic Ocean. Precisely, in an area for which there was hardly any paleontological data on these marine mammals, with the exception of the fossils of Catalonia, and far from the rest of the domain of the ancient great ocean Tethys, which separated Europe-Asia from Africa, and where have found most of these animals (Egypt, India and Pakistan). Among the most remarkable remains of the 550 fossils of Aragon arethree skulls, two whole with dentition, several scapulae, humerus and ulnas, and numerous ribs and vertebraefrom different areas of the skeleton of these marine mammals. Most of the fossils are in preparation for detailed study.
The sirenians appear for the first time in the Eocene (geological period between 56 and 34 million years) in ancient Tethys. Preliminary studies seem to indicate that the remains found constitute a new species, but it is necessary to deepen the investigations under way to know the dugong sirenium that inhabited at the beginning of the Middle Eocene near the Sobrarbe Delta.
