An international team of scientists, including researchers from Germany and Great Britain, has described a new species of ancient marine crocodile, Enalioetes schroederi. Enalioetes lived in the shallow seas that covered large parts of Germany during the Cretaceous period about 135 million years ago.

This ancient crocodile was a member of the family Metriorhynchidae, a remarkable group that evolved a dolphin-like body plan. Metriorhynchids had smooth, scaleless skin, flippers, and a tail fin. They fed on a wide variety of prey, including fast-moving animals such as squid and fish, but some metriorhynchid species had large, serrated teeth, suggesting that they fed on other marine reptiles. Metriorhynchids are best known from the Jurassic period, with fossils becoming rarer in the Cretaceous period. Enalioetes schroederi is known for a three-dimensional skull, making it the best-preserved known metriorhynchid from the Cretaceous period.

Sven Sachs from the Bielefeld Natural History Museum and project leader said: “The specimen is remarkable because it is one of the few metriorhynchids known to have a three-dimensionally preserved skull. This enabled us to CT scan the specimen and learn so much about the internal anatomy of these marine crocodiles. The remarkable preservation enabled us to reconstruct the animal’s internal cavities and even its inner ears.”

Dr Mark Young from the School of GeoSciences at the University of Edinburgh explains: “Enalioetes gives us new insights into the evolution of metriorhynchids during the Cretaceous. During the Jurassic period, metriorhynchids developed a body plan that was radically different from that of other crocodiles – flippers, a tail fin, loss of bony carapace and smooth, scaleless skin. These changes were adaptations to an increasingly marine lifestyle. Enalioetes shows us that this trend continued into the Cretaceous, as Enalioetes had even larger eyes than other metriorhynchids (which were already large by crocodilian standards) and the bony inner ears were even more compact than in other metriorhynchids, a sign that Enalioetes was probably a faster swimmer.”

The perfectly preserved skull, complete with the first cervical vertebrae, was discovered over a hundred years ago by the German government architect D. Hapke in a quarry in Sachsenhagen near Hanover. The specimen has an interesting history. It was given to Henry Schroeder of the Prussian Geological Survey in Berlin for preparation and examination, where it was presumably added to the collection. This led to the assumption that the specimen was lost during World War II. The specimen was later rediscovered in the Minden Museum in West Germany. It turned out that the specimen had been returned to the finder, whose family brought it to Minden, where they found a new home after World War II and took the specimen with them. The crocodile has since become one of the most valuable specimens in the Minden collection.

The first description was made by Henry Schroeder of the Geological Survey of Berlin, after whom the species is named.

By comparing the fossil with specimens from other museum collections, Sachs and his team concluded that it was a species unknown to science.