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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]

Reference
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

A new domain for The Marine Reptiles Forum

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The marine reptiles forum, which was unfortunately hacked last year (2013) and has been offline for several months since, is now back up and running. Richard Forrest was able to salvage all the old posts and user information, and has restored the forum at a dedicated new domain: marinereptiles.org. The forum is home to an open community of fossil marine reptile researchers and enthusiasts, and is an  excellent place to discuss all manner of topics related to prehistoric marine reptiles. The site is run by Richard Forrest (plesiosaur.com), Mike Everhart (oceansofkansas.com), and myself, so we’ll do our best to minimise spam and approve genuine new members without too much delay. Registration is now open so see you there!

The marine reptiles forum

Written by Adam S. Smith

January 18th, 2014 at 5:33 pm

The Plesiosaur Directory wins the 2013 Golden Trilobite Award

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The Golden Trilobite is awarded annually by the Palaeontological Association to “high quality amateur and institutional websites that promote the charitable aims of the Association”. I’ve no idea who nominated my website this year, but my thanks go to whoever raised it to the attention of the the PalAss Council, because it was a welcome surprise to learn that the Plesiosaur Directory was awarded the 2013 Golden Trilobite.

The golden trilobite award

I’m obviously delighted and honoured for The Plesiosaur Directory to win this award, and I thank PalAss for  recognising the site in this way. The Plesiosaur Directory started life as a small Geocities hosted site way back in June 2001, under the full title of “THE PLESIOSAUR DIRECTORY: A REVIEW OF THE SAUROPTERYGIA”. The site transferred to its own domain in March 2006 (plesiosauria.com), and remained in a basic html format until 2011, when I finally learned a bit of php and launched a new version of the site. This has been steep learning curve for someone with no training, and things are only going to get more difficult, as my next task is to convert The Plesiosaur Directory to a database driven site (at the moment only the plesiosaur bites blog is database driven), which will make it far easier to update and manage. The site has received other accolades in the past, such as when the journal ‘Science’ featured it in the “best of the Web in Science” (2006, Vol 313, Issue 5791, P.1211), so I suppose this means I must be doing something right.

However, these accolades remind me that there’s so much work left to do. Frankly, I’m not satisfied with the site as it stands, and I’m fully aware there are a great many genera missing from the directory, and numerous pages are rapidly becoming out of date as palaeontology marches on relentlessly. Some of the content hasn’t been updated since 2001, and was therefore written by a 20-year-old student version of myself. Back then, I could barely string together a coherent sentence. There are all sorts of reasons why I’ve let things slowly slip a little. However, this award will spur me on to upgrade the code, fill in those missing gaps, update the various galleries and pages, and write blog articles more frequently. There’s certainly no shortage of topics to cover.

The Plesiosaur Directory isn’t the only site dedicated to plesiosaurs. There are, in my opinion, other sites equally deserved of such an award. The Plesiosaur Site (plesiosaur.com), in particular, run by Richard Forrest, contains a wealth of data on plesiosaurs. Especially useful is the database containing information on plesiosaurian collections, distribution, taxonomy, and references. A major inspiration. Richard also hosted The Marine Reptiles Forum on plesiosaur.com until it was hacked earlier this year. We hope to get that back up and running soon.

For more information on the Golden Trilobite, including previous winners, see here. 

Written by Adam S. Smith

November 10th, 2013 at 5:10 pm

Pliosaurus kevani – the Weymouth Bay Pliosaur

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I’ve been rather quiet again recently, however, as coauthor of an article just published in PLOS ONE, I’ve good reason to come out of my shell today. The new paper describes and names the Weymouth Bay Pliosaur, a spectacular almost complete skull over 2m long. As discussed in the open access paper (take a look), the specimen is sufficiently different from all other pliosaurs to warrant a scientific name of its own, Pliosaurus kevani.

Weymouth Bay Pliosaur

Pliosaurus kevani was named to honour Kevan Sheehan, the Osmington Mills café owner who collected most of the skull, piece by piece, over a period of eight years. Kevan collected chunks up to 60 kg each as they weathered out from the Jurassic aged Kimmeridge Clay Formation sea-cliff. The specimen was purchased with funding secured by Dorset County Council’s museum service from the Heritage Lottery Fund Collecting Cultures programme, and Dorset and Devon county councils. It was prepared between 2010 and 2011 by Scott Moore-Fay and went on public display in Dorchester County Museum in July 2011.

Richard Forrest, who was involved with the project from the beginning, first had the idea of putting together a ‘dream team’ of British plesiosaur specialists to study and describe the skull. This is the first collaboration of its kind among plesiosaur researchers (as far as I know), and I feel lucky to have had the opportunity to contribute to it under the driving force of our lead author, Roger Benson.

Weymouth Bay Pliosaur

Roger Benson (left) and Richard Forrest (right) collecting data from the Weymouth Bay Pliosaur – Pliosaurus kevani

The massive skull has a long snout, circular orbits, huge temporal openings for the jaw musculature, and a deep mandible. Large portions of the skull have been crushed flat during fossilisation, so one of my tasks was to reconstruct the skull to show how it might have appeared before it was flattened. After several versions and much input from Mark Evans, I’m pleased with how it turned out, and I think we’ve produced a pretty accurate reconstruction of Pliosaurus. On the basis of this reconstruction I’ve also had a go at restoring the life appearance of P. kevani in profile. Despite its large size and massive teeth, the head is rather gracile.

Weymouth Bay Pliosaur
Weymouth Bay Pliosaur

Pliosaurus belongs to a group of plesiosaurians known as thalassophonean pliosaurs. If you haven’t heard of them before, that’s because the name Thalassophonea, or “sea slayers”, was proposed just this year (Benson & Druckenmiller, 2013) for a natural group of derived giant pliosaurids including Pliosaurus, Liopleurodon, and Kronosaurus. Thalassophoneans were macropredators, that is, giant predators doing the sort of dirty work in the Middle-Late Jurassic and Cretaceous that rhomaleosaurids did in the Early Jurassic. The paper also discusses the evolution of pliosaurids. The earliest thalassophoneans have a long mandibular symphysis, but in later members the symphysis becomes shorter. This trend is related to a shift in the dietary habits of pliosaurs from primarily fish-eaters to macropredators. In conjunction with this trend, we demonstrate that pliosaurids tend to follow Cope’s Rule – they get larger throughout their evolutionary history.

Weymouth Bay Pliosaur

We also name two other new species of Pliosaurus in the paper, P. westburyensis and P. carpenteri, based on material in the Bristol Museum & Art Gallery from Westbury, Wiltshire. Again, there are morphological aspects of these specimens that distinguish them from one another, but don’t justify new genus names. So, add these new species to the existing list of valid Pliosaurus species and we find ourselves with a rather large number of species within a single genus. The others being: P. funkei, also known as Predator X, P. brachydeirus, P. rossicus, and there might be one or two more pending thorough description of the material. Some invalid species of Pliosaurus have recently been sunk too. Future research might show greater generic diversity among these species, but that’s really dependent on the discovery of more satisfactory fossil material.

Written by Adam S. Smith

May 31st, 2013 at 9:21 pm