Debate still continues over the maximum size of this Pliosaur

Ever since Liopleurodon featured in episode 3 of the ground-breaking BBC series “Walking with..” this short-necked plesiosaur, more commonly referred to as a pliosaur has been regarded as a truly huge predator.  The programme showed Liopleurodon snatching an unwary Eustreptospondylus from rocks and chomping female pphthalmosaurs in half before finally coming to a sad end stranded on a Jurassic beach.  Just how big was Liopleurodon?

At the time the writers and researchers for the TV series estimated that an adult male Liopleurodon could reach lengths in excess of 25 metres and weigh more than 150 tonnes.  If this were indeed the case then Liopleurodon with its 18 inch long teeth could lay claim to being the biggest carnivorous animal ever.

Fossil Discoveries Do Not Back Claims

However, the existing fossil evidence does not back up the BBC’s claims.  There are four species of Liopleurodon known, the first and the holotype for the Liopleurodon genus (L. ferox) was named and described by the French palaeontologist, H. E. Sauvage in 1873.  Sauvage was working with very poor material, basing his scientific description on some smooth-sided teeth found in France.  This is how Liopleurodon got its name (means smooth-sided tooth).  These remains are dated to the Callovian stage of the Jurassic, other Callovian remains ascribed to Liopleurodon have been found in France and England, over the years much more evidence has been unearthed but reconstructions, if correct only put L. ferox at about 10 metres long.

How Big Was Liopleurodon?

The Oxford museum has a partial mandible believed to be from another Liopleurodon (L. macromerus).  This measures over 2.8 metres in length, but the mandible is not complete.  Estimates of over 3 metres have been given for the full length of the jaws, this could indicate that this individual was considerably bigger than L. ferox.  Liopleurodon macromerus is also known from Jurassic deposits close to the river Volga in Russia.

The fearsome Liopleurodon. The CollectA Age of Dinosaurs Liopleurodon model, A fantastic replica of a Jurassic pliosaur.

This area yields a number of marine reptile fossils each year, to read an article on a recent pliosaur find:  Russian Scientists unearth Pliosaur remains.

Other fragmentary pliosaur remains indicate that individuals may have grown to lengths in excess of 18 metres, but these cannot be ascribed with certainty to the Liopleurodon taxon.

Huge Pliosaur from Mexico

In 2002, a joint German/Mexican expedition announced the discovery of a huge pliosaur in Mexico.  The animal was estimated to be at least 15 metres long, and probably a not yet fully mature adult, so this reptile still had some growing to do!  This creature was nicknamed “the monster of Aramberri” after the location of the fossil find.  The remains showed evidence of predation so perhaps an even bigger pliosaur had killed this relative youngster.  At the time, this fossil (the best preserved bits were some articulated vertebrae), was described in newspapers as being a Liopleurodon, although these remains have not been placed within any pliosaur genera.  The rostrum with some teeth were also found but since this discovery in 1985 and its pronouncement  in 2002, this element of the specimen has been lost.  Ironically, the research team excavating the fossil reported cutting themselves on the ancient teeth, as they were so sharp.

The sediments from which this fossil was recovered date from the Kimmeridgian stage of the Jurassic, a much later stage than the Callovian.  This has led palaeontologists to speculate that this specimen does not belong to the Liopleurodon group.

Until further fossils are found it looks the speculation on the size of Liopleurodon is set to continue.

The inspiration for the scene in episode 3 of “Walking with..” when the Liopleurodon snatches the Eustreptospondylus from rocks came from another BBC documentary team, who had filmed Killer Whales risking beaching as they pursued young sea lions.

To view Everything Dinosaur’s range of prehistoric animal models including Liopleurodon models: Models of Marine Reptiles including Liopleurodon.

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