Fans of a still-surviving megalodon, rejoice – a new species of deep-ocean shark has been identified. At just 5.5 inches long (about 144 mm), however, the American Pocket Shark is a bit smaller than the prehistoric super-predator.

Back in 1979, a single pocket shark was collected in the Eastern Pacific Ocean. It wasn't until February 2010 that another one was captured, this time in the Gulf of Mexico. To date, their preserved bodies are the only two specimens of the creature.

A few years ago, however, a team of US scientists set about more thoroughly examining the second shark. This involved inspecting it with a dissecting microscope, x-ray imagery, and CT scans. Among other things, it was found that it had fewer vertebrae than the first shark, plus much of its body was covered in light-producing photophores.

Based on a total of five such differences, it has now been determined that the Eastern Pacific and Gulf of Mexico sharks are separate species. The latter, now commonly known as the American Pocket Shark, has been scientifically named Mollisquama mississippiensis.

Should you be wondering about the second part of that title, the specimen was first noticed within a scientific collection of other fish by biologist Mark Grace, of the NMFS (National Marine Fisheries Service) Mississippi Laboratories of the National Oceanic and Atmospheric Administration (NOAA). He was joined in the subsequent study by professors Henry Bart and Michael Doosey, of Louisiana's Tulane University, along with colleagues from the University of Florida and the American Museum of Natural History in New York.

"The fact that only one pocket shark has ever been reported from the Gulf of Mexico, and that it is a new species, underscores how little we know about the Gulf – especially its deeper waters – and how many additional new species from these waters await discovery," says Bart, director of Tulane's Biodiversity Research Institute.

A paper on the research was recently published in the journal Zootaxa.

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