A bizarre ancient marine reptile has been formally identified – decades after its fossils were first discovered in Canada.
The 12-metre creature, Traskasaura sandrae, was a long-necked plesiosaur – a type of predator that lived alongside the dinosaurs – with a bizarre anatomy and a rare top-down hunting style.
“The fact that it had some very odd traits – it was a very weird-looking animal – made it basically impossible for researchers at the time to decide what it was and who it was related to,” Prof F Robin O’Keefe, a palaeontologist at Marshall University and lead author of the study, told BBC Science Focus.
The first fossil was discovered in 1988 along the Puntledge River on Vancouver Island, after lying in the ground for 85 million years. It was strikingly complete – skull, neck, limbs, and tail – but degraded on one side. “It looked good from far away,” O’Keefe said, “but the closer you got, the sadder it became – like melted ice cream. That made it almost impossible to identify.”
It wasn’t until a second, juvenile skeleton was unearthed that things began to fall into place.
“It was really well preserved, and this allowed us to verify some of the odd traits of the adult fossil to make sense of what we were seeing,” O’Keefe said. “It was the addition of this second skeleton that made it possible to assign this thing to a new species.”
Among its many oddities is its shoulder structure, which opens downward – unlike any other plesiosaur known.
Its flippers, meanwhile, are shaped like inverted aeroplane wings, with the more curved surface on the underside rather than the top. “This helped to accentuate the upstroke when it dived down,” O’Keefe said.
That’s significant because it suggests Traskasaura hunted in a highly unusual way: by diving down on its prey from above.
“If you think about reptiles swimming around in the water, light always comes from above, so animals tend to hunt upwards because they’re looking at prey silhouetted against the light on the surface,” O’Keefe said. “This animal didn’t do that.”
Its prey likely included ammonites – extinct, coiled-shelled relatives of modern-day squid and octopus – which it would have crushed with its heavy, sharp teeth.
Despite its menacing size and terrifying appearance, Traskasaura was by no means the apex predator of the ancient oceans. “It was big, but it didn’t have a very big neck or head,” O’Keefe said. “So if a mosasaur that’s got big teeth got a hold of it, it could have really torn it up.”
Still, Traskasaura were likely having a good time of it, with an abundance of food in the ocean at the time. But it wasn’t to last. Like all plesiosaurs, the species met its end at the mass extinction around 66 million years ago.
“They were doing really well, the ecosystem was relatively healthy, and then an asteroid hits and kills off all the big animals,” O’Keefe said.
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About our expert
F. Robin O’Keefe received his Bachelor’s degree in honours Biology from Stanford University in 1992 and his Ph.D. in Evolutionary Biology from the University of Chicago in 2000. He has held a faculty position at Marshall University in West Virginia since 2006, where he has taught over two thousand undergraduates in courses ranging from human anatomy to comparative zoology and earth history.
An acknowledged expert on marine reptiles from the age of dinosaurs, O’Keefe was awarded the 2013 Drinko Distinguished Research Fellowship for his work on plesiosaur reproduction.