Cue in music, something between the "Jaws" theme with "Jurassic Park." Now jump into the water, close your eyes and pretend it's 200 million years ago and that isn't a guppy zeroing in on your feet. It's a sharp-toothed pliosaur the size of a bus and he can smell you a long way off, judging by cutting-edge scanning technology and the physiology of crocodiles.
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Finding fossils remains as difficult as ever, but the latest imaging technology is enabling scientists to peer into the ancient bones, which has resulted in many a surprise. One is that pliosaur snouts contain intricate nerve systems akin to that of latter-day crocs and believe you me, the crocodilian have a very keen sense of smell. They also see unnervingly well.
The secrets of smell among the extinct pliosaur set were discovered by University of Bristol researcher Davide Foffa of the Earth Sciences department, who painstakingly collated 2,000 individual scans of a fossilized pliosaur skull that was "exceptionally well preserved," as he wrote, that had been found some five years ago in Dorset.
The pliosaur was the dominant marine reptile of the Upper Jurassic era 200 million years ago, insofar as paleontologists know to date. Meaning, one could always find some unknown beast even bigger and badder, but none have to date.
Though up to 12 meters in length, pliosaurs are believed to have dined mainly on fish, rather than say each other.
Little had been known of their biology or physiology until Foffa and his computer tomography machine came along.
"Looking at the CT scans, we found that there were some branches and unusual channels that we had never noticed before. We thought it was a good idea to follow them and trace them digitally," says Foffa. "At the end we discovered this extensive neurovascular web of channels."
"The structures suggest that this could be a sensory system, perhaps similar to crocodile pressure receptors or shark electroreceptors," he wrote in his paper, "Complex rostral neurovascular system in a giant pliosaur."
Foffa thinks they may have supplied blood and nerve connections to skin and soft tissue in the pliosasur snout. This would have helped pliosaurs hunt prey and manipulate food in the water, like a modern-day crocodile.
In the argot, the bone channels probably housed the maxillary artery and trigeminal nerve, which carried signals to and from the upper jaw and snout.
"We found that this kind of system we found in the snout could be linked to prey detection, in a way similar as crocodiles do. In crocodiles the trigeminal nerve goes to some receptor in the snout, which help them in detecting movement of prey," Foffa says.
Palaeontologists have long suspected pliosaur skulls contained small holes called foramina that lead to internal channels, but this is the first concrete evidence of it.
The particular pliosaur on which the discovery was made was around eight meters in length, with a large, elongated crocodile-like head, a rather short neck, and a plump whale-like body. Four powerful flippers helped propel the beast through water while its large jaws, containing teeth the size of cucumbers, seized and crushed prey.
It's believed the larger pliosaurs could have swallowed a cow in a single bite, not that there were cows 200 million years ago.
Pliosauroids survived the Cretaceous and Jurassic eras. Its name simply means "more saurian," being a derivation from the Greek words for "more" and "lizard." It's quite apt that its snout paraphernalia are reminiscent of that of crocodiles: the man who coined their name in 1841, Richard Owen, thought they were a missing link between dinosaurs and crocs. They aren't.