Newly discovered ancient crocodile reveals secrets of marine evolution

An international team of scientists has described a new species of ancient marine crocodile, Enalioetes schroederi, which lived approximately 135 million years ago in the shallow seas that once covered parts of modern-day Germany. Dolphin-like bodies, smooth skin, and fins and tail fins distinguished animals from the family Metriorhynchidae.

According to the Sci News service, the well-preserved skull and neck vertebrae of Enalioetes Schroeder were discovered over a hundred years ago by the German architect D. Hapke in a quarry in Sachsenhagen near Hanover. Unfortunately, the fossils of the ancient species were lost during World War II, but after years, they were found again in the Minden Museum in West Germany.

Initially, Henry Schroeder studied the new species from the Prussian Geological Survey in Berlin. In his honour, scientists who continued the analyses later named the ancient crocodile. As they explained in the "Journal of Systematic Palaeontology," Enalioetes Schroederi was a marine crocodyliform family Metriorhynchidae member. This family is best known from the Jurassic period, and fossils belonging to its species are much less frequently found from the Cretaceous period.

Members of the Metriorhynchidae were fully adapted to life at sea. They developed numerous anatomical features that facilitated this lifestyle. Due to their greater porosity, these included elongated and more streamlined skulls of lesser weight and lighter ribs and thigh bones. Metriorhynchidae also featured short forelimbs resembling paddles and larger hind limbs, similar to those of modern crocodiles.

Dr Mark Young from the University of Edinburgh's School of GeoSciences, who was involved in the research, noted: "Enalioetes gives us fresh insight into how metriorhynchids were evolving during the Cretaceous Period. During the Jurassic metriorhynchids evolved a body-plan radically different from other crocodiles – flippers, tailfin, loss of bony armour and smooth scaleless skin. These changes were adaptations to an increasingly marine lifestyle. Enalioetes shows us that this trend continued into the Cretaceous."

As Young explained, this is evidenced by, among other things, the larger eyes and the structure of the ears of the ancient crocodile, which allowed Enalioetes to be probably "a faster swimmer" than other Metriorhynchidae. Experts believe that Enalioetes schroederi fed on various prey, including fast-moving animals such as squid and fish. It may also have preyed on other marine reptiles.