Scientists on Thursday announced the discovery of an almost complete fossil of the shark, called Aquilolamna milarcae, which lived in the Cretaceous period when dinosaurs ruled the earth.
Its unusual proportions – a wingspan of around 1.9 meters (6-1 / 4 feet) and a head-to-tail length of around 1.65 meters (5-1 / 2 feet) – amazed scientists .
The name Aquilolamna means “eagle shark”, a nod to its slender pectoral fins, which “acted mainly as an effective stabilizer”, according to vertebrate paleontologist Romain Vullo, lead author of the study published in the journal Science.
“There are many adjectives that can be used to describe this shark: unusual, unique, extraordinary, bizarre, bizarre. Yes, it is the only shark that is wider than it is long, ”said Vullo, affiliated with Géosciences Rennes, a research unit associating the University of Rennes and the National Center for Scientific Research (CNRS).
“Aquilolamna is indeed a perfect example of an extinct creature revealing an unexpected new morphology. This strongly suggests that other exceptional body shapes and morphological adaptations may have existed throughout the evolutionary history of sharks, ”said Vullo.
Like all sharks and associated rays and stingrays, Aquilolamna had a cartilaginous skeleton. It had the familiar torpedo-shaped body and tail of a shark, but its pectoral fins were quite unique. Researchers said the Aquilolamna appears to have been a slow-swimming shark that fed on plankton through filter feeding, as do whale sharks and plankton-eating basking sharks today.
The fossil, unearthed in the Mexican state of Nuevo Leon, did not reveal Aquilolamna’s filtering mechanism for eating.
Rays such as the manta ray, with their flattened bodies and large pectoral fins fused to the head, swim through the water as if they were flying through the air. Aquilolamna seems to have done something similar.
“While the locomotion of manta rays is like underwater flight, with flapping movements of their powerful pectoral fins, Aquilolamna’s long slender pectoral fins acted more like the wings of a glider or glider,” Vullo said.
Aquilolamna lived in the open sea at a time when the seas were populated by marine reptiles, squids with large shells called ammonites, various bony fish, and large sharks. The largest predator in its ecosystem was a shark called Cretoxyrhina, measuring 6 meters in length.
The group of fish that includes sharks appeared around 380 million years ago, long before dinosaurs.
Aquilolamna isn’t the only unusual shark to have swam in Earth’s oceans. Sharks and their loved ones came in many shapes and sizes – including a prehistoric one called Helicoprion which had a mouth like a spiral saw, another prehistoric called Stethacanthus which had a dorsal fin shaped like an ironing board, and the odd one. goblin and sawfish today. the Sharks. Reuters