An unusual, fossilized shark specimen found in northern Mexico shares characteristics with the manta rays it predates by 30 million years.
(CN) — Fossilized remains of an unusual species of manta-like shark that swam in the Gulf of Mexico 66 million years ago during the Late Cretaceous period show a link with manta rays that developed nearly 30 million years later, according to a new study published Thursday.
The study, published in the journal Science, reveals “an unexpectedly early evolutionary experimentation with underwater flight among sharks predating the rise of similar traits in manta rays and devilfish by more than 30 million years.”
The early fossil shark specimen is over 5 feet long with slender, “scythe-shaped” fins, whose 6-foot span exceeds the length of the animal. It has a short, broad head with a wide mouth.
The specimen was first discovered in 2012 in the Vallecillo quarry area in northern Mexico and was later purchased as a nearly complete skeleton for viewing by the Instituto Nacional de Anthropologie e Historia in a new public museum, the Museo La Milarca in San Pedro Garza Garcia, for its scheduled opening this year.
This manta-like shark feasted on plankton and soared through the ocean on its long, slender fins.
Lead author Romain Vullo of France’s University of Rennes and his colleagues named this new species of manta-like planktivorous shark Aquilolamna milarcae in their study.
Cartilaginous fish, a group that includes sharks, skates and rays, first appeared in Earth’s oceans around 380 million years ago and have since evolved, filling a diverse number of ecological roles.
These elasmobranchs, as they are known, are placed into one of two distinct categories – those with a more traditional shark-like body, for instance whales and basking sharks, and those with the flattened bodies and long sleek fins of rays. Aquilolamna milarcae falls somewhere in between.
According to Vullo and his team, the newly discovered extinct species shares many manta-like features, including unusually long, scythe-like pectoral fins and a wide mouth the researchers say likely adapted for filter-feeding of plankton. The shark also had a long, aerodynamic body and tail that reached its pinnacle in a distinct caudal fin like many other shark species.
The study suggests the unusual shark’s winglike fins evolved independently in each main lineage of filter-feeding elasmobranchs.
Vullo and his team interpreted the fossilized specimen as indicating that this species was a relatively slow swimmer, making use of both its long pectoral fins and tail to drift through the water all the while capturing suspended plankton with its wide mouth.