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Giant Prehistoric Sea Reptiles Hunted In The Same Way As Modern-Day Killer Whales

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Rachel Baxter

Copy Editor & Staff Writer

clockOct 15 2018, 14:25 UTC

Artist's impression of a Tylosaur by Charles R Knight for the American Museum, 1899. Wikipedia Public Domain

Millions of years ago, massive toothy reptiles swam the seas devouring any unfortunate ocean dwellers that got in their way. Now, a newly analyzed fossil suggests that these animals – called mosasaurs – may have battered their prey with their snouts, just like orcas do today. 

This idea has been proposed by University of Cincinnati biologist Takuya Konishi, lead author of a recent study published in the Journal of Vertebrate Paleontology that reanalyzed a fossil first discovered back in 1991 in western Kansas. The bones were originally thought to belong to a baby Platecarpus, a medium-sized mosasaur that grew to about 7 meters (24 feet) in length.

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But Konishi had suspicions the bones belonged to something else. It turns out that the fossil is actually the remains of a teeny tiny Tylosaurus mosasaur, which died very shortly after it was born. Much of it was likely consumed by other aquatic predators, but parts of its skull found their way to the seafloor, becoming buried for 85 million years.

Tylosaurus was the biggest of the mosasaurs, growing to a whopping 13 meters (42 feet) in length. It was an apex predator of the sea – think Jurassic World’s marine attraction (and unlikely hero).

While an adult Tylosaur’s skull would have been about 2.2 meters (7.2 feet) in length, the baby sea lizard’s measured just 30 centimeters (1 foot). The creatures gave birth to live young rather than laying eggs, so we know the little Tylosaur was a free-swimming baby, not an embryo when it died.

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If it had reached adulthood, it would have been an impressive predator with the ability to take down big prey. But how would it have done this? Well, having analyzed the fossil, Konishi thinks it would have used its bony snout to collide with its dinner and essentially stun it, before ripping its body to shreds. He will present his findings at the Society of Vertebrate Palaeontology conference later this month.

A protruding bony snout appears to be characteristic of the Tylosaur. Some mosasaurs had sharp teeth for munching on fish, while others had very strong jaws designed to crunch up the tough shells of turtles.

"It's a subtle feature perhaps by horned dinosaur standards, but for us it really signifies what kind of mosasaur you're looking at," Konishi explained in a statement. "If you have this protruding snout in this part of western Kansas, you're a Tylosaurus."

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And it seems the unique snout of the Tylosaur acted very much like that of an orca. Orcas, or killer whales, are famed for being accomplished predators, taking down anything from great white sharks and the calves of huge whales to helpless seal pups and speedy salmon.

Orcas stun their prey by whacking into it with their snouts, tails, or bodies. Tory Kallman/Shutterstock

"Killer whales don't hunt big prey by biting. They hunt by ramming and tearing them apart after the prey is weak," Konishi said. "They are chasing fast-moving animals so they use inertia. If they were swimming full speed at you, they would generate a lot of force. And their snout is conspicuously protruding."

It’s interesting to see that an ancient giant lizard and a modern-day marine mammal separately evolved this dramatic hunting tactic. Hopefully, the baby mosasaur fossil will help scientists find out even more about the evolution of this exciting yet intriguing group of long-extinct ocean giants.


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