However, it's not a precursor species to rays, but rather an example of convergent evolution, where different groups independently evolved the same features. This newly analyzed shark has features from both of these body types. Modern plankton-eating elasmobranchs have two distinct body shapes - those with "traditional" shark bodies, such as the whale shark (the largest living fish in the world), and those with flattened bodies, including the manta and devil rays. Sharks, manta rays and other fish with skeletons made of cartilage are part of a group called elasmobranchs, which emerged about 380 million years ago. The eagle shark's well-preserved fossil, along with the fossils of an ammonite ( Pseudaspidoceras pseudonodosoides), and bony fishes, including the needle fish ( Rhynchodercetis regio). This gives to Aquilolamna a unique chimeric appearance." "The other parts of the Aquilolamna, such as its tail and caudal fin, are like in many modern sharks. "Another interesting feature is that the head is short, with an indistinct snout and a wide mouth," Vullo added. "This makes the shark wider than long," with a "wingspan" of about 6.2 feet (1.9 meters) and a total body length of about 5.4 feet (1.65 meters). "One of the most striking features of Aquilolamna is that it has very long, slender pectoral fins," Vullo told Live Science in an email. This winged shark is unlike any shark alive today. When this shark was alive, that part of Mexico was covered by the Western Interior Seaway, a body of water that stretched from the Gulf of Mexico to the Arctic Ocean. A quarryman discovered the eagle shark specimen - a slab of limestone that preserved most of the shark's fossilized skeleton and imprints of its soft tissues - in Nuevo León, a state in northeastern Mexico, in 2012.
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