Paleontology often relies on superlatives to entice the public. Fossil species are touted as being the biggest, oldest, strongest, weirdest, or whatever other –est applies if the designation will help popularize a discovery. But, sometimes, hype precedes science.

In 2009, journalists heralded the arrival of “Predator X” – an immense, big-headed marine reptile said to have a bite four times stronger than Tyrannosaurus rex (the perpetual yardstick for all things prehistoric). The leviathan had only recently come out of the ground, and the researchers who discovered the aquatic hunter had not yet published a technical description of the beast, but news reports, a History Channel documentary, and even an unrelated schlock film declared the little-known pliosaur as the most badass predator of all time.

Six years after the fossil’s initial discovery, and three years after the peak of all the sensationalism, Predator X finally has a formal name. In the Norwegian Journal of Geology, paleontologists Espen Knutsen, Patrick Druckenmiller, and Jørn Hurum have dubbed the creature Pliosaurus funkei. (You’ll remember Hurum as the scientist star of the Predator X documentary, as well as the ringmaster who organized the media circus for “The Link” shortly thereafter.) But does the Jurassic ichthyosaur-cruncher live up to the media bombast?

Between 2004 and 2012, a University of Oslo team uncovered two big pliosaurs – short-necked, large-mawed, four-paddled marine reptiles – on the Arctic island of Svalbard. The only pliosaur material previously found there was a part of a tail vertebra, so the discovery of two pliosaurs was a major boon. The specimen ballyhooed as Predator X garnered greater fame, and the other enjoyed a brief moment in the media spotlight as “The Monster.” Both animals are specimens of Pliosaurus funkei, and both only allow partial views of what this marine apex predator was like in life.

Regular freeze-thaw cycles at the Svalbard locality severely fragmented the skeletons, Knutsen and co-authors report, and some of the fossils further “degraded” as they dried in the lab. In the case of the specimen used to establish the new species – PMO 214.135 – that material consists of jaw fragments, a smattering of vertebrae from the neck and back, and elements of the right forelimb. The second, larger specimen – PMO 214.136 – includes bones from the back of the skull, a few vertebrae, and “several fragmentary and unidentified bones.” Due to circumstances before and after their burial, there was frustratingly little left of the apex predators by the time the University of Oslo got to them.

The incomplete nature of both specimens complicates efforts to figure out how big Pliosaurus funkei was. With the smattering of petrified material in hand, Knutsen, Druckenmiller, and Hurum can only estimate the size of their animals based on measurements of other pliosaurs.

Both “Predator X” and “The Monster” were said to be about 50 feet long. When Hurum announced The Monster, in particular, he said it was “the biggest pliosaur found.” (He later backpedaled a little, but didn’t contradict the popular press estimates.) The new paper comes to a different conclusion.

The skull of PMO 214.136, Knutsen and colleagues estimate, would have been between about six and eight feet long when complete. That’s big, but comparable to the skull size of Kronosaurus – a pliosaur found in the Cretaceous rock of Australia and Colombia. The skull of the other Pliosaurus funkei was a little smaller – between five and six and a half feet long. That's still an impressive head, but not outside the range of what paleontologists have previously found.

Body length is another matter. Estimates of pliosaur size have been fraught by the fact that many species are only known from bits and pieces, and so paleontologists are left to estimate size based upon bones thought to act as a proxy for length. On the basis of vertebrae measurements, Knutsen and colleagues estimate that Pliosaurus funkei was about 33 to 42 feet long, which puts them “in the same size range as the largest specimens” analyzed by Colin McHenry in his Ph.D. thesis.

Without complete Pliosaurus skeletons, it’s difficult to know whether the newly named species fell on the longer or shorter end of the spectrum Knutsen and co-authors have hypothesized. Still, Predator X and The Monster were not the extreme record holders they were advertised as. Rather than being the biggest of all marine predators, Pliosaurus funkei is now cast by its describers as “one of the largest pliosaurs described so far” (a finding paleontologist Steven Salisbury anticipated in 2009 when he pointed out that pliosaurs over forty feet long were “not unheard of” prior to the Svalbard finds).

Our view of Pliosaurus funkei is grossly incomplete. This oceanic hunter was big and terrifying, that's beyond question, but the pliosaur fossils are not quite so big or spectacular as the media feeding frenzy suggested. And despite early claims that Predator X had a bite force of over 15 tonnes per square inch, such figures are suspect when we don’t even know what the pliosaur’s complete skull looked like. No bite force analysis was included in the description. Furthermore, Knutsen and collaborators “urge caution in drawing far-reaching conclusions of pliosaur ecology and behaviour” based upon their study. Pliosaurus funkei must have been an apex predator with a devastating bite, but there’s apparently little more than can be said with confidence. So much for “the most fearsome animal ever to swim in the oceans.”

Reference:

Knutsen, E.M., Druckenmiller, P.S. & Hurum, J.H. 2012. A new species of Pliosaurus (Sauropterygia: Plesiosauria) from the Middle Volgian of central Spitsbergen, Norway. Norwegian Journal of Geology, Vol 92, pp. 235-258.