A very odd looking shark with wing-like fins roamed the waters in the northeastern state of Nuevo León, Mexico around 93 million years ago. At that time, that specific part of Mexico was home to a body of water called the Western Interior Seaway that went from the Gulf of Mexico to the Arctic Ocean.
The shark species, which is called Aquilolamna milarcae (nicknamed “eagle shark”), looked quite similar to today’s devil rays and mantas which both have wing-like fins. In fact, the Aquilolamna milarcae had other similarities to devil rays and mantas such as what they ate – they feasted on plankton-like creatures. This suggests that the ancient shark lived in the same type of water that devil rays and mantas currently occupy.
As for what it looked like, Romain Vullo, who is a vertebrate paleontologist with the National Center for Scientific Research (CNRS) at Geosciences Rennes in France and the lead researcher of the study, explained in an email to Live Science, “One of the most striking features of Aquilolamna is that it has very long, slender pectoral [side] fins.” “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).”
Vullo went on to say, “Another interesting feature is that the head is short, with an indistinct snout and a wide mouth.” “The other parts of the Aquilolamna, such as its tail and caudal [tail] fin, are like [those] in many modern sharks. This gives to Aquilolamna a unique chimeric appearance.”
Another interesting fact was that it wasn’t a fast swimmer. Additionally, the fossil didn’t contain pelvic fins of a dorsal fin (the triangular fin that sticks out of the water), but just because they weren’t found with the fossil doesn’t mean that it didn’t have them. And none of the shark’s teeth were preserved which are normally needed to categorize species although the researchers did put it in the Lamniformes shark group.
As for why it went extinct, it’s currently unknown, but the deadly asteroid that hit Earth around 66 million years ago that killed the dinosaurs may have had a deadly impact on the sharks as well. (An image of what the Aquilolamna milarcae would have looked like and a picture of the fossil can be seen here.)
The study was published in the journal Science where it can be read in full.
In other ancient species news, recently found remains of an ankylosaurid that roamed around Mongolia’s Gobi Desert between 84 and 72 million years ago revealed that it was over 6 meters in length (20 feet) and based on its large forelimbs and forefeet, it was probably a great digger. Ankylosaurids had four short but very powerful legs, an armored body with wedge-shaped bony protrusions, and a tail club. It was also an herbivore.
Yuong-Nam Lee from Seoul National University in South Korea stated, “These armored dinosaurs, especially the Asian species, lived in arid to semiarid environments. They may have been able to dig out roots for food, and dig wells to reach subsurface water as modern African elephants do today.” While some small dinosaurs were believed to have dug burrows, overall, digging dinosaurs are pretty rare. (A reconstructive image of an ankylosaurid digging can be seen here.)
The study was published in Scientific Reports where it can be read in full.