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Plesiosaur Bites

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

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Written by Adam S. Smith

August 29th, 2017 at 5:28 pm

Six years of new plesiosaur replicas (2012-2017)

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It is hard to believe that the last time I wrote about plesiosaur toys here was in March 2011, over six years ago (http://plesiosauria.com/news/index.php/new-plesiosaur-replicas-for-2011/). Since then, many more new plesiosaur figures have hit the shelves, well, online stores – you’ll do well to find any of these toys in actual brick and mortar stores. The least I can do at this stage is summarise some of the latest additions to my ever-growing collection of plesiosaur models over the past several years.

Safari Ltd

Safari Ltd have added two plesiosaurs to their Wild Safari line since they released their Liopleurodon in 2010: an Elasmosaurus (2013) and a Kronosaurus (2017). I was grateful for the opportunity to work closely again with the Safari Ltd sculptors as a consultant on these.

CollectA

In 2011 I praised CollectA as a “blossoming company” and the CollectA flower has continued to blossom in subsequent years. They have produced four plesiosaurs, including familiar and obscure taxa, Dolichorhynchops (2012), Pliosaurus (2015), Thalassomedon (2016), and Kronosaurus (2017). The company has a reputation for selecting species other than the usual suspects, and for that I’m glad, we have more than enough Elasmosaurus and Liopleurodon already.

Both Safari Ltd and CollectA released a large Kronosaurus in 2017. This presented picky collectors with a difficult choice since both models are very good. CollectA have also released miniature versions of the ‘Deluxe’ size Pliosaurus and their older standard size Liopleurodon as part of their growing series of tube collections.

Geoworld

2014/2015 saw the release of three plesiosaurians by Geoworld in their Sea Reptiles Collection: Kronosaurus, Liopleurodon and Elasmosaurus. They’re nothing special and pretty bad when it comes to accuracy but still irresistible to completists like me. I unboxed the entire Sea Reptiles Collection on the Dinotoyblog Youtube channel if anyone is interested.

Bullyland presented a single plesiosaurian offering in the last half decade: a Liopleurodon with an articulated jaw in 2016. Good to see the German company still in the picture, at least.

Lastly, to round up the group, De Agostini is a newcomer to the world of plesiosaur toys. The Italian company created some particularly cute plesiosaurians as part of their ‘Dinosaurs and Friends’ children’s book series. A family of Plesiosaurus (mummy, daddy and baby) and a father and son pair of Kronosaurus.

That’s not an exhaustive list but it is more than enough to keep collectors on their toes!

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Written by Adam S. Smith

July 23rd, 2017 at 4:19 pm

Book review: Kronos Rising: Kraken (vol. 1), by Max Hawthorne

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“[His] mind began to shut down in an effort to preserve his sanity” – Garm Braddock in Kronos Rising: Kraken (vol. 1)

Hawthorne’s mahoosive Kronosaurus imperator is back and this time she’s brought her buddies along for the ride. This sequel to Kronos Rising (which I reviewed here) is set decades after the events of the first book, in a world where pliosaurs now run amok. Oceanic ecosystems are in turmoil and it’s time to get military on these bastard reptiles! Beefcake brothers Garm and Dirk are at the heart of proceedings as they take steps to emerge victorious from the raging ‘Saurian War’. Little do they know the titular Kraken is waiting to arrive on the scene to cause even more havoc…

Kronos Rising: Kraken (vol. 1.) cover

I won’t comment in detail on the story, style, tone, characters, and so on. I have opinions, of course, but who am I, as a lowly palaeontologist, to judge? All I’ll say is that it wasn’t to my taste. What I can focus on, as I did in my previous review, is the science. The aspects of the book that only a pedant like me will get his undies in a bind over. So, that’s what I’ll do – it’s panty twisting time.

One of my criticisms of the original novel was the dubious status of the species Kronosaurus imperator. This is the sort of nit-pick that only the most hard-nosed academic would rest any importance on, but I noticed the issue is still not resolved in Kronos Rising: Kraken. It means the species is technically invalid – a nomen nudum. This strikes me as somewhat appropriate given Hawthorne’s proclivity for exposing his characters’ most intimate fleshy parts.

Generally the anatomical descriptions are very good (n.b. I’m talking about the reptiles now!) and Hawthorne has done research to ensure the scientist characters use the correct language and terminology. However, he’s also not afraid to take liberties. For example, in the book, pliosaurs lay spherical eggs in nests, whereas we know sauropterygians gave birth to live young. The pliosaur’s teeth are described as sharply ridged with razor-sharp ends, whereas the course ridges on pliosaur teeth aren’t sharp, and pliosaur teeth really taper to a blunt bone-crushing apex. The fictional monsters skin consists of a “thick hide covered with rock hard scales”, yet it “absorbs 30% of the oxygen they need from the water”. In reality, there would have to be a compromise – skin has to be thin to absorb oxygen. In my Kronos Rising review I compiled a long list of the pliosaur’s superpowers. We can now also add camouflage onto said list. Don’t get me wrong, these are not complaints per se, I’m just saying. The key word to remember here – fiction. Let it go, let it go!

As with the previous novel, there’s a worrying infatuation with large size, be it the size of the creatures, the vessels, the machinery, the architecture, Dirk’s penis, Garm’s penis. “What can I say? Size matters!” chuckles one of the characters in the book. If you, too, believe size matters, then this is the book for you!

While Kronos Rising: Kraken (vol. 1) didn’t float my boat, aficionados of maritime monster fiction should probably pick up a copy and judge for themselves. Can thousands of Hawthorne’s fanatic ‘Legions of Kronos’ be wrong? Kronos Rising: Kraken (vol. 1), is available from Amazon.com here and Amazon.co.uk here. The official Kronos Rising website is located at http://www.kronosrising.com and you can also visit and like the Kronos Rising Facebook Page here, where Hawthorne makes a special effort to engage with readers, and sometimes puts forward his own interesting pet paleontological hypotheses. Lastly, thanks go to Max for the review copy – I hope you don’t regret the kind gesture!

A quick additional note. The original Kronos Rising novel now has a swanky new front cover, featuring amazing artwork. Check it out!

Kronos Rising new cover

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Written by Adam S. Smith

July 14th, 2016 at 1:24 pm

Investigating plesiosaur swimming using computer simulations

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One of the many areas of controversy in plesiosaur palaeobiology is the topic of how they swam. The question goes back almost 200 years to the 1820s when the first complete plesiosaurs were described from the Jurassic cliffs of Lyme Regis, UK. Plesiosaur swimming is a particularly difficult topic to study for a number of reasons. Plesiosaurs are extinct so there are no modern descendants, they have a unique body plan with no modern analogues, and swimming animals tend not to leave a good trace fossil record. All of this leaves us in a sticky predicament, but there are avenues we can explore to come to a greater understanding of plesiosaur locomotion.

Previous researchers have tried to answer the question of how plesiosaurs swam by conducting detailed osteological analyses, while others have approached it experimentally using robotics, or humans with fabricated paddles. These studies have started to settle on some consensus but there is still some uncertainty. The topic can also be explored experimentally through computer simulation and I was fortunate enough to be involved in such a study in collaboration with colleagues at the Georgia Institute of Technology. Our findings were published today in the open access journal PLOS Computational Biology (Liu et al. 2015).

Meyerasaurus swimming

Rendering of the Meyerasaurus victor plesiosaur model used in the study by Liu et al 2015.

What did we do?

We built a full-size, 3D, virtual plesiosaur, placed it in a simulated fluid, and gave it articulated joints so that it could propel itself through the fluid. We ran thousands of simulations to find the optimal ranges of limb motion and gaits – those that moved the animal forward the furthest. We did so multiple times under different specified parameters to see how different available ranges of joint motion effected the results. To investigate the potential contribution of the different limbs, some of the simulations used all four limbs while others used the forelimbs or hind limbs only. You can check the open access paper for the technical details.

What did we find?

We generated a lot of results in the form of videos. The simulations with the most plausible ranges of motion have a flying stroke with a large up-down component. This is essentially a form of underwater flight similar to penguins and turtles. One of the key questions we wanted to explore was how the forelimbs and hindlimbs moved relative to each other. Our results were inconsistent in this regard, which is significant in itself. The ‘forelimb-only’ simulations are just as fast as simulations using all limbs, which implies that the forelimbs were the powerhouse in plesiosaur swimming while the hindlimbs were more passive, at least during steady cruising.  However, in ‘hindlimb-only’ simulations, where the hind-limbs were asked to do all of the work, the rear flippers flail around a lot but the motion isn’t transferred into thrust or forward motion. Instead, in these simulations the whole plesiosaur rocks around the centre of body mass – apparently a rear-drive plesiosaur is a no-goer. This physical constraint probably explains why no other animals have adopted this unusual body plan, and it also explains why the gait is so variable in our simulations – the hind limbs provide so little thrust during cruising that how they move relative to the forelimbs is irrelevant.

plesiosaur swimming with all four limbs in large range

An example of one of the simulations. This one shows optimal swimming in a simulation of all four limbs using the widest joint range parameters. The parameters in this particular simulation are probably beyond the biologically possible limits of the joints, but other simulations had more conservative ranges (see the paper for all the videos).

 

plesiosaur swimming with all four limbs in large range - tip traces

To help us understand the limb strokes we traced the tips of the limbs. This one shows the limb tip traces for the above simulation, viewed posterolaterally. The hind-limbs in this simulation used only a small proportion of the available range.

 

Out of curiosity (and not included in the paper), we also manually simulated some specific limb strokes as hypothesised by previous plesiosaur researchers: rowing,  figure-of-8 flying, and modified flying. However, none of these manual simulations were as efficient as the best simulations found in our study through optimisation.

Does the method work?

Can we be sure that the method works and how do we know? Without a time machine we can never be completely certain that simulations of extinct organisms are correct. However, we can test the methods by applying them to models of animals for which their swimming is already known. In this case, our method was applied to several modern day animals including a turtle, a fish, and a frog (Tan et al. 2011). In each modern day animal the simulations were consistent with the biological reality, which suggests that the virtual reality is mirroring actual reality. This gives us confidence in our method.

New questions raised

Our simulations may shed light onto some old questions, but they raise new ones. If the hind limbs weren’t used for steady swimming, why are they so similar in shape and size to the forelimbs? Our study focussed entirely on propulsion but not on steering or stability, so we suggest that the hindlimbs may have helped the animal change direction more efficiently. Another alternative is that the rear flippers may not have been used in steady cruising – the sort of swimming our method focussed on – but may have instead been used for sudden short-lived bursts of speed. This sort of behaviour would be unstable over long distances (and so our method would reject it), but the hind flippers may have helped the plesiosaur lunge at prey or avoid a larger predator.

Plesiosaur tip traces

Tip-traces of the most efficient limb strokes resulting from simulations with all four limbs. The top simulation explored a narrow range of available motion, the middle simulation explored a medium range of available motion, and the bottom simulation explored a wide range of available motion (probably exceeding the biological limits of joint motion).

The future

We hope to explore the above questions about the function of the hind limbs in the future. There’s plenty of scope for other related studies on different plesiosaurs or other extinct swimming animals. For example, we selected a plesiosaur with a generalised morphotype for this study, but plesiosaurs as a group are highly variable. We’d like to look at some of the more extreme morphotypes in the future, the long-necked elasmosaurids and short-necked pliosaurids, to see how the proportions of the body impact the simulations. We also focussed all of our attention (and computing power) on how the limbs move, because that was our main focus. However, we acknowledge that the tail and neck may also have been important in locomotion. This is something else we hope to explore in the future. In the meantime, every journey must start with a first step, or – in this case – a first flap.

Liu S, Smith AS, Gu Y, Tan J, Liu CK, Turk G. (2015) Computer Simulations Imply Forelimb-Dominated Underwater Flight in Plesiosaurs. PLoS Comput Biol 11(12): e1004605. doi:10.1371/journal.pcbi.1004605

Tan J., Gu Y., Turk G., and Liu C. K. 2011. Articulated swimming creatures. ACM Transactions on Graphics, 30(4), 58:1–58:12.

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Written by Adam S. Smith

December 18th, 2015 at 7:42 pm