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Mine’s bigger than yours! The Monster of Aramberri, Predator X, and other monster pliosaurs in the media

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During the past decade several dramatically named giant pliosaurs have hit the mainstream media, many claiming to be the biggest yet discovered. But only a trickle of peer-reviewed literature has been published to accompany these news stories. The lack of published data makes it really difficult to sift the facts from the fiction, and it’s easy to get the different stories muddled up, especially in the case of two identically sized congeneric pliosaur specimens from Svalbard: ‘The Monster’ and ‘Predator X’. So in an attempt to iron out the details and assess what we really know about all these specimens, here’s a short summary of the main players.

The Monster of Aramberri
Hit the mainstream media: 2002.
Estimated length in media: 18 m.
Conservative estimated length 15 m.
Material: Partial vertebral column, proximal end of a femur, part of the pelvic girdle, and cranial fragments. The fragment of rostrum collected in 1985 is now lost.
Where: Aramberri, Mexico.
Excavation: The original excavation in 1985 yielded a partial rostrum and vertebral column. The excavation site was reidentified in 2001 and additional material was collected during 2001 and 2002.
Peer-reviewed scientific references: Buchy et al. (2003).
Notes: The material was collected over a period of several years, but the discovery only hit the mainstream media in 2002 when more substantial pieces of the skeleton were discovered. An excellent account of the ‘Monster of Aramberri’ is given here by Richard Forrest. Buchy et al. (2003) described UANL-FCT-R2, the partial vertebral column discovered in 1985 [pictured below], but the majority of the skeleton has not been described and is in the process of being prepared. I’ve confirmed with Marie-Celine that the vertebrae described in 2003 are part of the ‘Monster of Aramberri’, but it is worth noting that the 2003 paper doesn’t explicitly mention ‘The Monster of Aramberri’ by name. Originally referred to Liopleurodon, it isn’t considered so any more (Buchy & Frey, 2003).

Monster of Aramberri vertebrae

Part of a figure from Buchy et al. (2003) showing some of the vertebrae and girdle elements of 'The Monster of Aramberri' of the

The Monster
Hit the mainstream media: October 2006
Estimated length in media: 15 metres
Conservative estimated length: 13-15 m
Material: anterior part of rostrum, two cervical and numerous dorsal vertebrae, a nearly complete coracoid and right forelimb, and several dorsal ribs and gastralia.
Where: Svalbard, Norway.
Excavation: Discovered in 2006 and excavated in 2007.
Peer-reviewed scientific literature: none.
Notes: ‘The Monster’, not to be confused with ‘The Monster of Aramberri’, was the first pliosaur from Svalbard to be excavated and the first to make the news. A second giant pliosaur (‘Predator X’, see below) was discovered at the same time, but was excavated the following season. Richard Forrest’s 2008 article on the plesiosaurs from svalbard provides a thorough discussion, including comments on ‘The Monster’, but it was written before the second pliosaur hit the mainstream media.

Paddle of 'the monster'

Partial forelimb of 'The Monster'

Predator X
Hit the mainstream media: March 2009
Estimated length in media:
15 m
Conservative estimated length: 13-15 m
Material: Partial skeleton including posterior skull region and anterior cervical vertebrae.
Where: Svalbard, Norway.
Excavation: Discovered in 2006 and excavated in 2008.
Peer-reviewed scientific literature: none.
Notes. The fossil material attributed to this pliosaur was first mentioned in stories covering “The Monster” in 2008, but the name ‘Predator X’ was coined after the specimen was excavated and it hit the media in 2009. According to an SVP poster by Knutsen et al. (2009) both ‘The Monster’ and ‘Predator X’ belong to the same taxon – they are congeneric and they are closest in their anatomy to Pliosaurus. They are both estimated to be the same size, and they are also both from the same geological formation, so with all these similarities it’s easy to confuse the two. ‘Predator X’ inspired the cover story for the 31 October 2009 issue of New Scientist, and was the main subject of a recent History Channel documentary of the same name, which also featured another giant pliosaur – the Weymouth Bay pliosaur. ‘Predator X’ will also appear in the BBC’s upcoming series Planet Dinosaur. Despite its widespread presence in the news and on TV, I was unable to find a suiatable photograph of the actual material.

The Weymouth Bay pliosaur
Hit the mainstream media: October 2009
Estimated length in the media: 16 m
Conservative estimated length: 12 m.
Material: skull and mandible (missing the tip of the manibular symphysis).
Where: Weymouth Bay, Dorset, UK.
Excavation: Discovered in pieces over a period of time – specific details unclear. The specimen was purchased by Dorset County Museum in Dorchester.
Peer-reviewed scientific literature: none.
There is an excellent account of the Weymouth Bay pliosaur here by Richard Forrest. The skull as preserved is 2.1m long.

The Weymouth Bay pliosaur

The Weymouth Bay pliosaur and Richard Forrest


So there we have it, four mega-pliosaurs making big news in the space of a decade. All of them have conservative and realistic length estimates around the 15m mark, with the Weymouth Bay pliosaur possibly slightly smaller and ‘The Monster of Aramberri’ possibly slightly larger. But all the estimates are way too wooly to take seriously just yet. So all these monsters will remain jostling for top spot until the scientific papers are published, and until we have a better understanding of pliosaurid proportions.

There are or course plenty of other giant pliosaurs, which frequently pop up in discussions too, including additional real contenders for ‘biggest pliosaur ever!’. While I do plan to write more on giant pliosaurs in the future, I’ve stuck to the ones in the mainstream media for now. You might have noticed that Liopleurodon was conspicuously omitted from this post. Well, although it is entirely relevant to the present topic, it hasn’t been in the news recently so I decided to leave the magical Liopleurodon alone this time around. It will be nice to write about a pliosaur with an actual scientific name for a change, even if that’s opening a can of worms in itself!


Buchy, M.-C. & Frey, E. 2003. Was it really eating granite? We’re searching hard: history of the Monster
of Aramberri (and stories about it). First meeting of the EAVP – abstracts, 39.

Buchy M.-C., Frey E., Stinnesbeck, W. ; López-Oliva J.G. 2003. First occurrence of a gigantic pliosaurid plesiosaur in the Late Jurassic (Kimmeridgian) of Mexico. Bulletin de Societe géologique de France, 174, 271-278.

Knutsen, E., Druckenmiller, P., Hurum, J., Nakrem, H. 2009. Preliminary account of new Late Jurassic pliosaurid material from Svalbard, Norway. Journal of Vertebrate Paleontology, 128A.

Noè, L. F., Smith, D. T. J. & Walton, D. I. 2004. 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.

Written by Adam S. Smith

April 5th, 2011 at 6:32 pm

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Monstertalk Podcast – The Plesiosaur Hypothesis

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Monstertalk is a new sceptical podcast focussing on all things cryptozoological. The most recent episode (episode 004) delves into the idea that plesiosaurs may still be alive today, lurking in lochs and lakes around the world – the so called Plesiosaur Hypothesis.  I was interviewed as a guest on this episode and took part in a long discussion about plesiosaur palaeobiology. I’ll admit that I was hesitant to be interviewed at first because I don’t want to get too bogged down or involved in the living plesiosaurs ‘debate’.

MonsterTalk logo

The word debate goes into inverted commas because very few cryptozoologists really take the plesiosaur hypothesis seriously, any discussion on the topic is less of a debate and more of a debunk. The plesiosaur hypothesis is really only pushed by 1. the occasional fundamentalist creationist under the (false) impression that a living plesiosaur would somehow discredit evolution (which it obviously wouldn’t), and 2. the media. The media’s fascination with Nessie is especially irksome, no plesiosaur-based science news story in the popular press is self explanatory or interesting enough, it seems, without the inevitable comparison with a fabled creature that doesn’t look like a plesiosaur anyway. This perpetuates the public’s only frame of reference for plesiosaurs as Nessie and does nothing for palaeontology and even less for science education.

Loch Ness Monster hoax

It was partly with this in mind that I decided to accept the invitation to be interviewed on Monstertalk, but moreover it was an excellent opportunity  to talk about plesiosaur palaeontology and the real mysteries surrounding these fascinating creatures. Far more interesting than those mythical lake monsters I think, and I hope that’s how the podcast came across. I enjoyed the experience although I still haven’t had the courage to listen to myself twittering on. This episode is available to download as a free MP3 here: and the show notes are here: I highly recommend listening to the other episodes too. Enjoy!

Written by Adam S. Smith

September 5th, 2009 at 9:00 pm

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‘Sea Monsters – Prehistoric Creatures of the Deep’ book review

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I recently read and reviewed Mike Everhart’s new book for the online Journal Palaeontologica Electronica, I reproduce it here:

Sea Monsters book

Sea Monsters – Prehistoric Creatures of the Deep, is the official companion to the recently released IMAX movie of the same name. As Everhart explains in the preface to this book (and in the final chapter), both the movie and this book have their roots in the ‘Sea Monsters’ cover story featured in the December 2005 issue of National Geographic Magazine. The story introduced readers to Mesozoic marine reptiles, presenting information on a wide range of species throughout the Mesozoic Era, and from fossil locations all around the world. For the purposes of the movie, it was necessary to select a single geographical location and point in time. As scientific consultant to the Movie, Everhart sold the ‘Oceans of Kansas’ as the perfect setting for the movie; after all, Late Cretaceous seas were “probably the most dangerous seas ever on this planet”. And so it was that The Western Interior Seaway and many of its ferocious inhabitants were resurrected on the (very!) big screen. Sea Monsters, the book, allows readers to dig a little deeper into the history and science behind the movie.

Sea Monsters is a large format and highly visual volume. As one would expect from a National Geographic publication and official companion to a 3D movie, the selling point of this book is the imagery. Each of the 191 glossy pages in this book feature stills from the movie, numerous computer-generated artworks (including reproductions of those presented in the 2006 National Geographic Magazine cover story), historical photographs and photographs/illustrations of fossils and skeletons. For the most exciting visuals, however, don the complimentary pair of 3D glasses (to be found in a pouch on the inside back cover) and open up the 3D sections: between each chapter is a selection of three-dimensional stills from the movie, many of which occupy double-page spreads.

Chapter one asks: “what is a sea monster?” The question isn’t really answered (there is no meaningful answer), but allows Everhart to divulge into the diversity of prehistoric marine reptiles, with short sections on the origins and habits of ichthyosaurs, plesiosaurs, turtles, and mosasaurs; and to outline their place in prehistory. The end of this chapter focuses on the Western Interior Seaway, setting the scene for some of the following chapters, which will describe the environment and food webs of the Late Cretaceous period. Chapter two looks at the historical context of marine reptiles, and in particular, the major scientists and ‘fossil finders’ involved in the discovery of the many creatures preserved in the deposits of the Western Interior Seaway. Chapter three reviews the fauna – all of the key ‘characters’ in the movie are outlined and illustrated. Chapter five provides an overview of the extinction theories proposed to explain the disappearance of many of the groups 65 million years ago. The last chapter comprises a ‘making of’ section. Much like Sternberg’s famous fossil fish within a fish, nestled amongst each chapter are short self-contained sections; these ‘Close Up’ and ‘Album’ sections provide a little more detail, or a ‘case study’, on some aspect mentioned in passing in the main text.

The scientific content is basic and aimed towards a popular adult audience. Although a separate children’s book is also available (Sea Monsters: A Prehistoric Adventure
by Marfe Delano Ferguson), the style and depth of text in Sea Monsters- Prehistoric Creatures of the Deep, is certainly accessible to older children. The tone of the book is in keeping with the aims of the movie, to simultaneously entertain and educate. Marine reptiles have long been overlooked and overshadowed by dinosaurs in vertebrate palaeontology books and children’s books on prehistoric life, but this is slowly changing: look out dinosaurs, here come the sea monsters!

The book is available from Amazon for a very reasonable price.

Sea Monsters – Prehistoric Creatures of the Deep
By Michael J. Everhart

Written by Adam S. Smith

December 5th, 2007 at 12:17 pm

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Arctic pliosaur is new species

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Another giant pliosauroid plesiosaur fossil from Arctic Svalbard Islands appears to represent a new species. The specimen was discovered and initial excavations took place in Summer 2007. The treasure trove of marine reptile fossils were first discovered in 2006 by a team from the University of Oslo, Natural History Museum, led by Dr. Jørn Hurum and Hans Arne Nakrem; they discovered ichthyosaurs and a large pliosaur, which became known as the ‘Monster’ in the popular press. The new pliosaur was uncovered when the team returned to the locality – it seems to be the same species as the original ‘Monster’. The collected parts of the fossil include teeth, skull fragments and vertebrae, but the specimen is only partly uncovered and so the dig will continue next year. A more detailed review of the findings will also be presented next year.

arctic pliosaur

Image by Tor Sponga, copyright Natural History Museum, University of Oslo, Norway

Written by Adam S. Smith

December 5th, 2007 at 12:08 pm

Posted in Uncategorized