22 million years old

Find in Traun: New primeval dolphin species discovered

The flattened state of the dolphin fossil Romaleodelphis pollerspoecki made it particularly difficult to examine the anatomy of its skull. Lateral view.(Bild: APA/M. Schellenberger, SNSB-BSPG)

During the construction of a power plant near Traun (Linz-Land district, Upper Austria) in 1980, private collector Jürgen Pollerspöck discovered the remains of a prehistoric dolphin that lived in a shallow estuary in this region around 22 million years ago. German researchers have now identified the dolphin as a previously unknown species and genus and named it "Romaleodelphis pollerspoecki".

Pollerspöck handed the find over to the Bavarian State Collection of Palaeontology and Geology in Munich for preparation and storage. "All that remains of 'Romaleodelphis pollerspoecki' is its not quite complete skull, with an elongated snout and 102 uniform teeth," explained first author Catalina Sánchez Posada from the Ludwig Maximilian University of Munich, who examined the fossil with colleagues from the Bavarian State Collection and the Senckenberg Research Institute and Natural History Museum.

Different from anything known to date
The coastal section of the primeval Paratethys Sea, in which the prehistoric dolphin romped together with many other organisms such as various protozoa, algae, mussels, snails, squid relatives and fish during the Miocene period, extended slightly north of the Alps, which were just emerging at the time. As the analyses of the remains showed, the animal belongs to the group of toothed whales, but differs significantly from all previously known original representatives.

"New insights into their evolution"
Romaleodelphis is probably related to the now extinct, very primitive dolphins of the so-called Chilcacetus lineage. The fossils of this lineage to date all come from the north-eastern Pacific and the coasts of South America. "The discovery of 'Romaleodelphis pollerspoecki' as a possible relative of this lineage from Europe could provide new insights into its evolution and origin in the earliest Miocene," said Gertrud Rößner, curator of fossil mammals at the Bavarian State Collection in a press release.

Animal had excellent hearing
The dolphin skull found near Traun is severely compressed, which made the examination of its anatomy particularly difficult. With the help of a computer tomograph, it was nevertheless possible to analyze internal features. The anatomical reconstruction of the fossil's inner ear in particular yielded remarkable results. The prehistoric dolphin is likely to have had excellent hearing in the high-frequency range - similar to that of modern dolphins. This makes "Romaleodelphis pollerspoecki" one of the oldest known toothed whales that had a sense of hearing similar to that found today in porpoises, for example. These animals can communicate in frequency ranges that are beyond the hearing range of their predators.