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Thaumatodracon – the Wonder Dragon

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In 2012 I co-presented a poster at the SVP annual meeting on a new plesiosaur from Lyme Regis, UK (see my article about it here). The long awaited follow up paper was finally published this summer in the latest volume of Palaeontographica A (Smith and Araújo, 2017) and the beast now has a name, Thaumatodracon wiedenrothi, meaning ‘Wiedenroth’s Wonder Dragon’.

The Lower Saxony State Museum commissioned artist Luzia Soares to create a stylistic impression of Thaumatodracon. Copyright L. Soares 2017

Thaumatodracon was a top-predator that cruised around the shallow Tethys Ocean that covered Europe about 195 million years ago. It had a 60 cm long skull with dozens of sharp teeth, an estimated total body length of 6.5 m, and may have weighed around 2 tonnes. The specimen was collected from Lyme Regis in 1969 by Kurt Wiedenroth, an amateur German palaeontologist to whom we dedicated the new species name. The Niedersächsisches Landesmuseum Hannover (Lower Saxony State Museum) acquired the specimen later that year where it was subsequently prepared by Elijah Widmann during the 1990s.

Kurt Wiedenroth hunting for ammonites in Lower Cretaceous deposits near Hanover, Germany. Kurt discovered Thaumatodracon wiedenrothi in Lyme Regis in 1969. Photo courtesy of Sönke Simonsen.

The nearly complete skull and neck of this plesiosaur are exquisitely preserved, and Ricardo Araújo and I visited the Lower Saxony State Museum in Hanover in 2011, where we identified it as a new species that fills a gap in the fossil record of rhomaleosaurids. Diagnostic ones, anyway. The holotype of ‘Plesiosaurus’ macrocephalus, also from Lyme Regis, could well be a rhomaleosaurid, but since it is a juvenile it is difficult to diagnose. Our findings in Hanover were too late to include in my PhD thesis dedicated to rhomaleosaurids, but better late than never.

The preserved parts of the skeleton – the head and neck – are highlighted in dark grey

The holotype specimen, laid out in dorsal view.

Details and interpretation of the skull

In addition to a thorough comparative description, we conducted morphometric analyses to compare Thaumatodracon to all other rhomaleosaurid plesiosaurs. We found that the new taxon possesses transitional characteristics that are consistent with its intermediate position in the plesiosaur family tree. This is also more or less what we would predict to find because it is from the Sinemurian, which makes it stratigraphically intermediate between the older Hettangian rhomaleosaurid fauna (Atychodracon) and younger Toarcian rhomaleosaurid fauna (Rhomaleosaurus, Meyerasaurus).

The new genus is a nod to ‘Thaumatosaurus’, a powerful name that was once used interchangeably with Rhomaleosaurus. It was also widely applied to the holotype specimen of Meyerasaurus victor before I came along and made ‘Thaumatosaurus’ a nomen dubium (see my article about that here). So, I chose the name Thaumatodracon as atonement, but also because plesiosaurs were true wonders of the prehistoric world and Ricardo and I wanted to give this new species a name to reflects that.

Rhomaleosaurids have traditionally been regarded as pliosaurs. Although we called Thaumatodracon a pliosaur in our original poster presentation, the position of Rhomaleosauridae within Plesiosauria has since become disputed. Several studies now suggest that the rhomaleosaurid family diverged from other plesiosaurs before the pliosaur/plesiosauroid dichotomy, which is why we avoid calling Thaumatodracon a pliosaur in our paper.

The journal has requested that I do not share the PDF publicly, but I’m free to email it, so drop me an email if you’re interested: [email protected]

Smith, A.S. and Araújo, R. 2017. Thaumatodracon wiedenrothi, a morphometrically and stratigraphically intermediate new rhomaleosaurid plesiosaurian from the Lower Jurassic (Sinemurian) of Lyme Regis. Palaeontographica Abteilung A, 308 (4-6), 89-125. doi:10.1127/pala/308/2017/89

Written by Adam S. Smith

August 29th, 2017 at 5:28 pm

Monograph on Rhomaleosaurus thorntoni

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Many readers will be familiar with the giant plesiosaur on display in the marine reptiles gallery of the Natural History Museum, London. This is a cast of the 7 metre long holotype of Rhomaleosaurus cramptoni, the original of which is housed in the National Museum of Ireland (Natural History) and formed the basis for my PhD thesis back in (time flies!) 2007. However, The Natural History Museum, London, also has its very own massive (also ~7 m long) and quite real Rhomaleosaurus type specimen to rival the ‘Dublin Pliosaur’ in size. NHMUK PV R4853, the mighty Rhomaleosaurus thorntoni, is from the Toarcian (Lower Jurassic) of Northamptonshire. It was donated to the museum prior to 1922 but has never been described and figured in its entirety before.

Rhomaleosaurus cramptoni

Rhomaleosaurus cramptoni cast on display in the NHM, London


My newest paper, co-authored with Roger Benson (Smith & Benson 2014), provides a detailed description and photographic atlas of the entire skeleton of Rhomaleosaurus thorntoni, and it was published by the Palaeontographical Society just in time for me to distribute copies to colleagues at the SVP annual meeting in Berlin last November (2014). Few monographs of this kind, i.e. a comprehensive treatments of a single taxon, exist for plesiosaurians, especially up-to-date ones, so the paper should prove useful. The monograph includes 35 photographic plates depicting, essentially, every bone in the skeleton from multiple angles. We describe the skeleton in detail and figure the more complicated elements as interpretive illustrations. It’s just a bigger than average descriptive paper, really, but one that has been many years in the making (even more than it usually takes!). I’ve been waiting for the published monograph to be listed on the Palaeontographical Society publications page prior to posting this article, but since it is not yet forthcoming I decided to post this anyway. I’ll update this blog entry with a link to the volume once it is listed. [Edit – here is the link]:

Rhomaleosaurus ilia

Rhomaleosaurus thorntoni ilia (Plate 33 from Smith & Benson [2014])

The entire manuscript, including the photographs and figures, is completely new: this is not a rehash of my PhD thesis on Rhomaleosaurus. The skeletal reconstruction is brand new as well and I hope that it comes to replace my previous reconstruction of Rhomaleosaurus in time, which I was never completely satisfied with (figured in Smith [2007], Smith & Dyke [2008], and Smith [2013]). It is important to highlight that the new reconstruction represents R. thorntoni specifically, which we demonstrate is a distinct species, whereas the previous reconstruction represented Rhomaleosaurus sp. using R. cramptoni where possible and R. thorntoni as a proxy where not. As such, the original reconstruction was a mishmash of two different species, with related scaling errors. Most of the differences apparent between the new and old reconstructions are, however, due to stylistic improvements and a greater attention to detail, rather than genuine anatomical differences between R. cramptoni and R. thorntoni. The lateral view, especially, had some perspective issues with the ribs and limbs, which are corrected in the new reconstruction. There is still some margin for error in the proportions of the tail and neck in the new reconstruction because these are incomplete in the holotype (and only known specimen) of R. thorntoni, but I’m much more satisfied with it.

Rhomaleosaurus thorntoni

Rhomaleosaurus thorntoni reconstruction. Scale bar = 1m.

There is some doubt over the systematic position of rhomaleosaurids. They are traditionally regarded as pliosaurs, but they might not really be included within that clade, so for this reason we refrained from referring Rhomaleosaurus to Pliosauroidea in the title. We don’t include a cladistic analysis in our monograph to investigate this question, but we do summarise all previous ones and identify areas of relationship consensus within the clade Rhomaleosauridae. More cladistic work is required to confirm whether rhomaleosaurids are an early plesiosaurian offshoot, or pliosaurs proper.

Rhomaleosaurid cladograms

Ingroup relationships of rhomaleosauridae according to different researchers (text-fig 11 from Smith & Benson [2014])

So, where’s the PDF? Sadly, there isn’t one, and this has been discussed and debated in some detail over at SV-POW (here). I say ‘there isn’t one’, but what I really mean is that distribution of the PDF is forbidden, since a beautiful PDF does exist (I was annotating it in the final proof stages). I was hopeful that permission would be granted for me to share the final PDF along with the hard copies provided for authors to distribute, but it was not to be. Of course, I’m disappointed about the barrier this puts between my research and potential readers, and I’m concerned about the impact this might have on it being cited. However, the hard copy is a quality publication, which can be thought of as more of a book than a paper. Those individuals that require it for research purposes can always request one from me directly – I can’t make promises but drop me an email if you have a serious interest ([email protected]).

The Palaeontographical Society funded some of my visits to the Natural History Museum to see the fossil material and this influenced my decision to select the Monograph of the Palaeontographical Society as a publication venue for this work. Plus, the format suits such an exhaustive treatment. I’d  like to thank the editor, Yves Candela, who made a significant contribution to the volume and coordinated the whole process.

Update: The monograph is now available for sale from the Pal Soc website here.


Smith, A. S. 2007. Anatomy and systematics of the Rhomaleosauridae (Sauropterygia: Plesiosauria). PhD thesis. University College Dublin, 278pp.

Smith, A.S. 2013. Morphology of the caudal vertebrae in Rhomaleosaurus zetlandicus and a review of the evidence for a tail fin in Plesiosauria. Paludicola 9 (3): 144–158.

Smith, A.S. and Dyke, G.J. 2008. The skull of the giant predatory pliosaur Rhomaleosaurus cramptoni: implications for plesiosaur phylogenetics. Naturwissenschaften, 95, 975-980.

Smith A.S. and Benson R.B.J. 2014. Osteology of Rhomaleosaurus thorntoni (Sauropterygia: Rhomaleosauridae) from the Lower Jurassic (Toarcian) of Northamptonshire, England. Monograph of the Palaeontographical Society, London: 168 (642), 1–40, pls 1–35.

Written by Adam S. Smith

January 8th, 2015 at 12:58 pm

A new Lyme Regis pliosaur

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Earlier this month I co-authored a poster at SVP 2012 describing a new pliosaur from the Sinemurian of Lyme Regis (Smith and Araújo, 2012). I was unable to attend the conference in person so my collaborator and friend Ricardo Araujo was on hand to present our preliminary findings.

Ricardo Araújo stands proudly next to our poster at SVP 2012. Ricardo is conducting a PhD on plesiosaurs at the Southern Methodist University, Texas.

The spectacular specimen was discovered at Black Ven, Lyme Regis, and was acquired by the Niedersächsisches Landesmuseum, Hanover, where it was expertly prepared in the 1990s by their preparator, Elija Widman. The fossil consists of an almost complete skull and vertebral column.

The Lyme Regis pliosaur as articulated

As explained in our poster, the fossil represents a new taxon that is both stratigraphically and morphologically intermediate between known Hettangian and Toarcian rhomaleosaurid pliosaurs. Which makes perfect sense. A legible (just about) jpg version of the poster is available here or by clicking the small version below, and a PDF of the abstract is available here. This is very much a work in progress though and more of a sneak preview than a final word. We have a paper in prep which will provide a more detailed description of the specimen.

Poster for SVP 2012

Smith, A.S. and Araújo, R. 2012. A new rhomaleosaurid pliosaur from the Sinemurian (Lower Jurassic) of Lyme Regis, UK. Program and abstracts, 72nd Annual Meeting of the Society of Vertebrate Paleontology, Supplement to the online Journal of Vertebrate Paleontology, 74. [PDF here]

[Incidentally, how does one cite an SVP abstract correctly these days?]

New plesiosaur replicas for 2011

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A couple of new plesiosaur figures will be released in 2011, both from blossoming company CollectA. As a UK-based company CollectA has a tendency to choose British taxa, sometimes rather obscure ones. So forget Elasmosaurus or Kronosaurus, CollectA have gone out of their way to produce the first ever replica of two wonderful British Jurassic taxa: Rhomaleosaurus and Attenborosaurus.

Rhomaleosaurus was the subject of my PhD project so it’s fantastic to see it turned into a toy. I’ve written a full review of this figure over at the dinosaur toy blog (here)

Rhomaleosaurus CollectA

I’ve discussed my favourite plesiosaur Attenborosaurus here on the blog before, as I’ve been closely involved with the Trinity College cast (see previous posts here and here). Again, it’s great to see a more unusual taxon reproduced in toy form and I’ll review this figure properly soon.

Attenborosaurus CollectA

That’s it for new plesiosaur figures for 2011, but who knows what the future might bring…

Written by Adam S. Smith

March 22nd, 2011 at 7:01 pm