Walking With Dinosaurs (1999) - Controversy

Liopleurodon dwarfs Ophthalmosaurus in the Late Jurassic Tethys Ocean, 149 Ma, Oxfordshire, England.

Liopleurodon (in the television show only) was a true giant of a marine reptile carnivore. Adult males could reach 25 metres long, weighing in at a staggering 150 tonnes. The largest teeth were 30 cm long with jaws that were 3 metres long on total skull length of 5 metres. The flippers which could reach 4 metres in length - which helped power it through the water to catch even the fastest marine animals like Ophthalmosaurus.

They lived as solitary carnivores, most likely behaving in the same way as some apex predator sharks do in their habitats - swimming at depth, and looking for silhouettes at the surface to then attack with extreme velocity and fatal impact force. No individual solitary carnivore has ever been this large or this deadly.

Episode 3 - Cruel Sea

Liopleurodon Beached on an island

Liopleurodon featured in the third episode of Walking with Dinosaurs - Cruel Sea. At the beginning, one Liopleurodon snatched a Eustreptospondylus offshore, and took it underwater. Later apparently the same animal, an old male of immense size even for his species, attacked and killed a female Ophthalmosaurus that was unfortunate enough to be attacked whilst having difficulties giving birth. She was bitten in two. Then he fought a much younger female for territory, and won, injuring one of her flippers.

Later on however, he was beached by a fearsome Jurassic tropical storm, and became a living banquet for Eustreptospondylus. However, it was made clear that whilst the giant was still alive, his great jaws were lethal.

Instead of eat him alive - because the Dinosaurs themselves could be killed - the scavengers waited for the old Liopleurodon to pass away. The marine adapted lungs of the Liopleurodon were being crushed under the giant's own 150 tonne body. Death by exhaustion and suffocation, was inevitable. When the Eustreptospondylus were compared to the Liopleurodon, this again showed how enormous the television version was.

Walking With...Specials

Liopleurodon featured in Sea Monsters: A Walking with Dinosaurs Trilogy. In Sea Monsters several Liopleurodon are seen feeding on Leedsichthys, which are extinct giant fish much longer than Liopleurodon in truth. In Sea Monsters, the Liopleurodon are depicted at a much smaller scale than the huge old male portrayed in the episode Cruel Sea from the main series (less than half the size of that one in most shown)

Scientifically Accurate Size (as of 2020): and notes on Scientific Speculation

There are two accepted/recognised species; Liopleurodon ferox and Liopleurodon pachydeirus.

The largest species, also far better understood than the rarer L.pachydeirus, is Liopleurodon ferox. This well-known species, L.ferox, is estimated to have grown up to:

6.39 metres (approx. 21 feet) in length (vs 25 metres/82 feet in the TV series which popularised Liopleurodon globally)

6.39 metres: or 639 centimetres: or approx. 6,390 millimetres. General estimates for typical Liopleurodon ferox specimens = broadly speaking between 5 and 7 metres.

Clearly, this is notably smaller than the somewhat excessive 25 metres figure used for Liopleurodon in Walking With Dinosaurs. However, it is important to keep in mind that all science evolves rapidly, and particular hints of more spectacular possibilities in the fossil record, can sometimes lead even the most well-meaning experts in a subject to propose more unbelievable figures. Television shows are happy to run with the more spectacular estimates.

According to anecdotes from the primary scientific adviser for the episode, as listed in the credits, he had advised a figure of around 18-20 metres, though the producers and the director of Walking With Dinosaurs in 1999, wanted to essentially "tack on" another 5 metres as a margin of speculation so to speak. In the animal kingdom, we may observe many rarer individuals among various species, that are considered "giants" compared to the average sizes of animals you will see with most of a given species. This is highly logical, as mutations and variations in populations of the vast majority of animals will have a certain range.

Even the 18-20 metres figure being tentatively (though some might say, optimistically) suggested by the scientific adviser, and based on some promising, yet fragmentary fossil evidence found at the time, was rather huge. The fact that humanity has so much to learn about the present day oceans, leaves far, far more to be desired regarding our knowledge of the Mesozoic seas. However, scientific speculation can only or perhaps should only go so far, and the primary fossil evidence for Liopleurodon ferox was very clearly nowhere near 25 metres.

Two examples of Pliosaurs known to be bigger than Liopleurodon, include species of the Pliosaurus genus (e.g. Pliosaurus funkei), which could grow up to 10-13 metres long, and Kronosaurus, which could grow up to a length of 9-10.9 metres. It is therefore not so much of a stretch of the imagination to envisage the potential for 15 metre long giants among the Pliosaurs - though not 25 metres, as that is quite a leap.

On Speculations...

Though it is tempting to think of Liopleurodon or some other Pliosaur reaching such huge sizes, most evidence points to an animal a fraction the size of the colossal animal portrayed in Walking With Dinosaurs. Doubtlessly, there could still be major fossil evidence yet to be found of particularly large specimens, of Liopleurodon ferox.

Even so, the most promising fossil fragments of Liopleurodon ferox in particular, seem to suggest an animal no longer than roughly 7 metres (still a pretty scary marine reptile, and not something you'd want to swim alongside necessarily, though less than a third the length of the beast shown in WWD)

6.39 metres is therefore the reliable benchmark figure we have so far, although claims of fossil fragments suggesting far, far larger Liopleurodon, sometimes become rumoured. Making speculations of giants based on what was very fragmentary evidence at best, may well be criticised, though for the purposes of popularising marine reptiles with a new audience at the time, it was a forgivable addition one must speculate (though at the time, and ever since, the dimensions of the Liopleurodon portrayed, have been a source of considerable dispute and some palaeontologists and science editors in newspapers were rather unimpressed with what looked like blatant sensationalism, with some criticisms mentioned in the papers in 1999 in the UK)

Whether it was a poor choice, is a matter of debate, though the compelling and dramatic scenes in Walking With Dinosaurs certainly increased public engagement and interest about these less famous reptiles (compared to the Dinosaurs, for instance) A fair amount of artistic and dramatic license was always assumed with the depictions in Walking With Dinosaurs - best guesses based on the best available interpretations in 1999. It would be completely unfair to judge the series by the exact same expectations we'd have of media over 20 years after the episode first aired in the UK and globally.

Another hidden positive of the WWD Liopleurodon controversy, is how it inspires genuinely healthy discussion about the scientific accuracy of popular portrayals of prehistoric animals on the silver-screen. The very fact that there is active discussion of this obviously vital aspect of palaeontological reconstructions, is helpful. It reminds us to do our best to keep to the best available scientific evidence. The somewhat dubious decision to opt for the maximum size estimates, could well be called out as simply pandering to sensationalism for the sake of making good television - though in that case, it certainly did it's job, did it not? (are you not entertained?)

It is correct form to hold more outlandish and less excusable claims of a science programme to a higher standard of expectation and scrutiny, though it does stray into repetitive and outright unfair necromancy of criticisms that keep getting brought up over and over again about something that was released in 1999. Criticising the errors in something is perfectly fine, it is just how that is then contextualised that matters.

Contextually, it would actually be very strange if a programme from over two decades ago, got away with getting nothing wrong. Hindsight is easy, after all. Working on the best available fossil evidence and contextualising it with everything else understood about the palaeoecology and palaeoenvironment of any particular species, it soon becomes obvious that there will always be serious mysteries and gaps in our understanding.

Ultimately, Liopleurodon may have simply been a moderately sized Pliosaur, living alongside larger marine reptiles and fishes. However, one must remember that the absence of evidence, is not necessarily the evidence of absence, when speculating on low sample size, lower preservation tendency fossils.

It would be wrong to be too strident in our claims about species so old as this, and we don't even have enough largely complete specimens to be sure of an even partially complete ontogenetic/life cycle process, evidenced with many fossils from juvenile to elderly adult. We only have one largely complete, and beautiful specimen of Liopleurodon ferox. This is the well-preserved 6.39 metres long specimen.

Did Pliosaurs keep growing throughout their lifespans like some reptiles do today? Would there be some long-lived Liopleurodon approaching 8 metres? 9 metres? 10 metres? These things are surprisingly hard to estimate, especially as we lack enough postcranial (fossil evidence beyond just the skull) fossils from more fossil specimens of this particular species, to really be sure with greater confidence, what figures to propose for upper size estimates. Without a more complete understanding of the life cycle of an animal, and how bodily proportions appear over the ontogenetic cycle, it is impossible to know for sure. It would be a strong and deadly marine predator, regardless.

Walking With Dinosaurs - The Evidence (book)

American Palaeontologist Thomas R. Holtz, Jr. (note: not the main adviser on the episode Cruel Sea, though the main adviser for episode 6 Death of a Dynasty and one of the series consultants for the entire series)

- from: "Walking with Dinosaurs - The Evidence" (scientifically advised WWD book, 2000)

"This [25 metre] size created much debate ... as no palaeontologist thinks Liopleurodon really got this big. Although several complete skeletons have been discovered, these are individuals of between 5 and 10 metres in length. It is less complete remains discovered in the Oxford clay that indicate lengths greater than this, though here we move into an area of rough estimates and guesswork. A vertebra at Peterborough Museum would seem to indicate a pliosaur of between 17 and 20 metres, and various fragments of snout and lower jaw in other museum collections suggest specimens of similar size." End quote.

Note: that being over two decades old, such insights are, while still largely helpful when learning about Liopleurodon, potentially a little dated now in the 2020's. It shows an interesting behind the scenes perspective, though.

Classification and General Evolutionary History

Taxonomic Classification (Systematic Palaeontology):

Phylum Class Superorder Order Suborder Family Clade
Chordata Reptilia Sauropterygia Plesiosauria Pliosauroidea Pliosauridae Thalassophonea
Haeckel, 1874 Laurenti, 1768 Owen, 1860 Blainville, 1835 Welles, 1943 Seeley, 1874 Benson & Druckenmiller, 2013

Liopleurodon lived during the Late/Upper Jurassic Period, in the Callovian, Oxfordian and Kimmeridgian Stages (in chronological order, left to right; followed by perhaps the Tithonian Stage, if it is to be believed it lived into the very last Jurassic stage)

Etymology and a Brief Scientific History

"Liopleurodon", means "smooth-sided tooth", which derives from Ancient Greek words: leios ("smooth") + pleura ("side" or "rib") + odon, ("tooth")

The genus Liopleurodon was named in 1873 by French Palaeontologist and Ichthyologist Henri Émile Sauvage, based on rather limited fossil evidence (three teeth, none of which being from the same sites or individual animals logically)

Liopleurodon fossils have been found mainly in England and France.

Fossil specimens that are broadly contemporary (Callovian to Kimmeridgian Stages of the Jurassic Period) with those from England and France referable to Liopleurodon are known from Germany. Some fossil evidence of Liopleurodon may also have been been found in Argentina and Mexico.

External Links and Further Reading

External Links



Further Reading

- Notes sur les reptiles fossiles. - Bulletin de la Société Géologique de France, série 3 1:365-386 - H. -E. Sauvage - 1873.

- The first relatively complete exoccipital-opisthotic from the braincase of the Callovian pliosaur, Liopleurodon. - Geological Magazine 140 (4): 479–486. - Leslie F. Noe, Jeff Liston & Mark Evans - 2003.

- A new species of Kimmeridgian pliosaur (Reptilia; Sauropterygia) and its bearing on the nomenclature of Liopleurodon macromerus. - Proceedings of the Geologists' Association 115: 13–24. - L. F. Noè, D. T. J. Smith, D. I. Walton - 2004.

- A Giant Pliosaurid Skull from the Late Jurassic of England. - PLoS ONE 8 (5): 1–34 - Roger B. J. Benson, Mark Evans, Adam S. Smith, Judyth Sassoon, Scott Moore-Faye, Hilary F. Ketchum, Richard Forrest - 2013.

- Foffa, D.; Young, M.T.; Brusatte, S.L. (2018). "Filling the Corallian gap: New information on Late Jurassic marine reptile faunas from England" (PDF). Acta Palaeontologica Polonica63 (2): 287–313. doi:10.4202/app.00455.2018

See Also

Liopleurodon Gallery

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