Paleontologists have announced the discovery of an extraordinary fossil shark in Mexico. They describe Aquilolamna milarcae, a late Cretaceous shark which was wider than it was long, with a strange one thin pair of pectoral fins. This shark, far from a ferocious bite, maybe he survived by eating plankton.
The team’s research was published today in Science. The authors believe A. milarcae it was a lamniform, the same order that includes the great white shark and megamouth today. But the Cretaceous shark looked completely different, with a wide mouth, flat head and 6 legs wingspan reminiscent of rays. Although rays are also elasmobranches, the group of cartilaginous fish that also contain sharks and skates, A. milarcae precedes the appearance of his lookalikIt is, mantle and devil rays, about 30 million years old.
“Aquilolamna it is a shark; definitely, there is no problem “, said Romain Vullo, paleontologist at the University of Rennes in France and the main author of the paper, in a video call. “This offspring of sharks disappeared at the end of the Cretaceous without offspringnts. After that, the ecological niche became vacant, and then a offspring of batoids – rays –evolved into mantle rays. ”
Vullo described the shark as a languid predator, which, like all other sharks, I would have used them the tail wing to propel itself through the shallow sea that once occupied central North America. (This is another difference from the rays, which curl their wing-like wings to get from A to B.) After propelling itself, A. milarcae he would have used those remarkable pectoral fins to make the marine equivalent of the hang glider, running through the seas and probably swallowing the plankton that came his way.
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“This is really an interesting discovery,” Kenshu Shimada, a professor of paleobiology at DePaul University in Chicago and an expert on ancient shark species, said in an email. “The exact taxonomic identity of this new shark is still debatable, but the design of its body, especially the exceptionally elongated pair of pectoral fins, is unique not only in the order of the Lamniformes shark, but also in the whole world of sharks.”
He is not sure that the shark was a planktivor, but that’s the hypothesis of Vullo and his team, based on that the fossil had no teeth. This is surprising, as most ancient sharks are identified only by their teeth, as they are better preserved. than the skin and cartilaginous skeleton. The team raises the possibility that. A. milarcae is either a relative of or the same animal as Cretomanta, another elasmobranh who it is identified so far only by its dentition.
“When you work on a single specimen, even if it is very well preserved, you always lack some information, and here, the main information we want is the dentition,” said Vullo. “I would like to answer this: why was the dentition Aquilolamna, and check if it really is Cretomanta. ”
It is a Cretaceous approach Guess who?, where, instead of eliminating candidates for fossil sharks, more come to the surface. While this would be a misfortune for someone playing the game, it is an advantage for paleontologists, who continue to learn more about the biodiversity of the Earth’s prehistoric seas.