Crocodiles With Dolphin Tails: Fossil of Mysterious New Species Plugs Evolutionary Gap

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A Magyarosuchus fitosi crocodile catches a fish in this artist's impression of the extinct species. Márton Szabó

Scientists studying a 180-million-year-old fossil have discovered it's a member of a new species that plugs a gap in the crocodile family tree.

Heavy, bony armor protected the backs and bellies of some Jurassic-era crocodiles. Others lacked this layer but had dolphin-like tail fins and flippers. Researchers think the newly discovered species, which was heavily armored but sporting a fin tail, slots somewhere between these groups.

The fossil was found in Hungary's Gerecse Mountains in 1996 and then stored in a Budapest museum. Now, an international team of researchers from Hungary, the U.K. and Germany have analyzed the specimen. They published their research in the journal PeerJ.

The team named the new species Magyarosuchus fitosi after Attila Fitos, the amateur collector who discovered the fossil.

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A weird vertebra marked the creature as a member of a new species. Its shape suggested the presence of a tail fin, but other parts of the fossil clearly pointed to bony armor.

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A fragment of the fossil's left jaw is displayed. Attila Osi

The croc would have stretched about 16 foot long, about the same size as an average male saltwater crocodile today, and had large, pointy teeth. The research team thinks it was one of the biggest coastal predators of its time.

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"This fossil provides a unique insight into how crocodiles began evolving into dolphin and killer whale–like forms more than 180 million years ago," study author Mark Young from the University of Edinburgh said in a statement. "The presence of both bony armor and a tail fin highlights the remarkable diversity of Jurassic-era crocodiles."

The discovery "underscores how little is still known about the timing and tempo" of adaptations among these kinds of ancient creatures, the researchers wrote in PeerJ.