The discovery of a fossil of an unusual shark specimen reminiscent of stingrays sheds light on the morphological diversity of Cretaceous sharks.
This plankton feeder was discovered in Mexico and analyzed by an international team of paleontologists led by a researcher from the National Center for Scientific Research (CNRS), who publishes their findings in the journal Science.
93 million years ago, strange winged sharks swam in the waters of the Gulf of Mexico. This newly described fossil species, called 'Aquilolamna milarcae', has allowed its discoverers to erect a new family. Like stingrays, these 'eagle sharks' are characterized by extremely long and thin pectoral fins reminiscent of wings. The specimen studied was 1.65 meters long and 1.90 meters wide.
The 'Aquilolamna milarcae' had a tail fin with a well developed upper lobe, typical of most pelagic sharks, such as the whale shark and the tiger shark. Thus, its anatomical characteristics give it a chimerical look that combines sharks and rays. With his large mouth and supposedly very small teeth, must have fed on plankton, according to the international research team led by Romain Vullo, from the CNRS.
Scientists have identified only one category of large plankton feeders in the Cretaceous seas so far: a group of large bony fish (pachycormidae), which is now extinct. Thanks to this discovery, they now know that a second group, the eagle sharks, was also present in the Cretaceous oceans, according to a CNRS statement.
The complete specimen was found in 2012 in Vallecillo (Mexico), a locality that produces remarkably preserved fossils. This site, already famous for its many fossils of ammonites, bony fish and other marine reptiles, is very useful for documenting the evolution of ocean animals.
In addition to shedding light on the structure of Cretaceous marine ecosystems, the discovery of the eagle sharks reveals a new, hitherto unsuspected facet of the evolutionary history of sharks.