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Why did elasmosaurids have such a long neck?

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It was once common knowledge that elasmosaurid plesiosaurs were bendy-necked beasts that swanned about near the surface, striking snake-like at slippery prey. It is now common knowledge that their necks were relatively rigid rod-like structures, the function of which remains something of a mystery. The truth, with regard to flexibility at least, is probably somewhere in between. The most recent study to provide estimates of flexibility in elasmosaurid necks gives ranges of motion in the region of 75–177° ventral, 87–155° dorsal, and 94–176° lateral, depending upon the thickness of cartilage present between adjacent vertebrae (Zammit et al. 2008). Visually, that looks something like this:

Elasmosaurid neck flexibility

Ranges of elasmosaurid neck motion as estimated by Zammit et al. 2008.

Elasmosaurids weren’t the completely stiff-necked creatures they’re sometimes made out to be — even a tiny amount of flexibility between vertebrae adds up when you have 70+ neck bones. But why did plesiosaurs have such a long neck in the first place? This is a difficult question to answer because 1. plesiosaurs are extinct and left behind no living descendants, and 2. there are no other extant aquatic long-necked organisms to provide analogues. To my knowledge (and correct me if I’m wrong) there are no long-necked fish, cetaceans, sea turtles, or any other long-necked organisms that spend their entire life underwater. At least not to the extent seen in plesiosaurs.

Elasmosaurids were weirdos, but they maintained this long-necked bauplan for 135 million years, so they were successful weirdos. The long neck also evolved independently in different plesiosaur lineages, some cryptoclidids have extremely long necks too, for example. This all indicates a strong selection pressure (or pressures) driving the evolution of the long neck in plesiosaurs, despite the great risk involved in exposing such a delicate part of the anatomy in an ocean filled with super-predators. The long neck was therefore obviously doing something(s) useful. However, we can only really guess what.

Here are the top possible functions for the long neck in elasmosaurids (I’ve ruled out those possibilities that would require flexibility greater than the estimates given above). Some of these ideas are reasonable and have been suggested before, while others are, ahem, unreasonable and quite ridiculous.

1. Stealth device. Fish are stupid. The long neck provided distance between the bulky body of the plesiosaur and the unsuspecting prey.

Elasmosaurid neck function

2. Getting into tight spots. Helpful for hunting in reefs, crevices, and kelp forests.

Elasmosaurid neck function

3. Sexual selection. The equivalent of a peacock’s tail – the longer and more brightly coloured the better.

Elasmosaurid neck function

4. Food storage. Hamsters have cheeks, plesiosaurs had necks. This might not be as ridiculous as it sounds. Leatherback turtles do something similar (despite their incredibly short necks) by having an extended oesophagus that wraps around the stomach. Their prey (usually jellyfish) is held in place in the oesophagus by backwards-pointing projections (papillae) while excess water is expelled. After temporary storage in the oesophagus the morsels are transported to the stomach. Perhaps elasmosaurids were jelly fish specialists too?

Elasmosaurid neck function

5. Bottom feeding. Hunting in soft sediment. I’m not sure how the long neck really helps here – maybe something akin to number 1?

Elasmosaurid neck function

6. A snorkel. An air supply for staying submerged for prolonged periods of time.

Elasmosaurid neck function

7. Surprise, mother flapper!

Elasmosaurid neck function

8. Energy saver. Moving costs energy, so a long neck might allow the plesiosaur to feed, slumped on the sea bed, hardly moving its body in the process.

Elasmosaurid neck function

9. Electrogenic organ. Plesiosaur necks housed electrocytes and so longer necks create higher voltage electric fields. For electrolocation (sensing prey), elecrofishing (stunning prey to be consumed at leisure), and/or electric defence (to protect from pliosaurs and mosasaurs). This hypothesis comes from here, and was raised to my attention by Darren Naish.

Elasmosaurid neck function

10. Wrench of death. Grab and twist – for pulling ammonites out of their shells. Originally suggested here – thanks again to Darren Naish for reminding me. Twist feeding has also been suggested for short necked pliosaurs, for which it makes morse sense to me.

Elasmosaurid neck function

Other suggestions are welcome! Edit – I’ve updated the list with some new suggestions and will add more soon based on the comments posted below…

References

Zammit, M., Daniels, C. B. and Kear, B. 2008. Elasmosaur (Reptilia: Sauropterygia) neck flexibility: Implications for feeding strategies. Comparative Biochemistry and Physiology, Part A, 150, 124–130.

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Written by Adam S. Smith

November 23rd, 2014 at 6:28 pm

Book review: Kronos Rising by Max Hawthorne

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“After 65 million years, the world’s greatest predator is back” – Max Hawthorne
“Oh blimey, we’re gonna die!” – an Englishman in Kronos Rising.

Note – this review contains minor spoilers.

Kronos Rising, the new novel by Max Hawthorne, is a man vs monster story of a giant pliosaur that terrorises a seaside Florida town. Author Max Hawthorne was kind enough to send me a copy of the novel to review and I promised to write about it here.

Kronos Rising cover

You might expect some resistance from me towards fanciful notions of pliosaur biology and physiology, but this isn’t the case, I’m always game for some science fiction, no matter how far fetched. Kronos Rising is no text book and it would be ridiculous to review it as such. However, a few comments on the science won’t hurt.

The eponymous pliosaur in Kronos Rising is a new species of Kronosaurus, dubbed Kronosaurus imperator. It isn’t specified what or where the type specimen is, or if the name is recognised by the ICZN, but that’s all by the by! The pliosaur – for there is only one – is a badass, just because, and I’m fine with that. She (it emerges that this pliosaur is female) surpasses bassassery into the realm of super-villainry, for she has a vast array of powers at her disposal. These include: bullet-proof armour, echolocation, infrared vision, a directional and “phenomenal sense of smell”, “sensitive eardrums” with an acute sense of hearing, “amplified power of healing”, “resistance to disease and bacteria”, a swimming speed in excess of 45 knots (52mph), and a bad temper to boot. When it isn’t killing it dreams of killing (no, really!). And, of course, at over 80 feet long (just over 24m), it is huge. Hawthorne goes out of his way to give his Kronosaurus imperator all the bells and whistles and it makes for a terrible foe!

Pliosaurs, of course, were not quite so terrible in reality, no real animal would have all of these adaptations. One sense – the sensitive underwater olfaction the pliosaur uses to track down its prey – is supported by evidence outlined in a Nature paper (Cruickshank et al. 1991), so Hawthorne has clearly done his research and consulted the literature. Most everything else is is speculation. Pliosaurs didn’t have armour or heavy-duty scales and were probably rather smooth like cetaceans are today, a more useful adaptation to an aquatic lifestyle. I’ve written before about the fossil evidence for huge pliosaurs, and the maximum size estimates level off at around 15m. Hawthorne’s speculative 24m long Kronosaurus is therefore an overestimate, but not outside the realms of possibility. We can roll with this – it’s science fiction.

The fascination with large size in the novel extends beyond the obvious immensity of the Kronosaurus itself, to massive boats and guns, strapping muscular men, and anglers out to seek the biggest catch. I know Max Hawthorne is a record breaking angler himself, so perhaps this is a fisherman thing? There are nautical terms aplenty throughout the novel and for that I appreciated the glossary at the back of the book. Still, I found the technical detail sometimes bogged down proceedings – I’m obviously a landlubber.

The novel contains several surprise twists but is generally conventional in both plot and character development. The love story, for example, is spelled out from the get go. The main male and female protagonists share troubled histories over which they can bond and this gives them both depth and motivation, but many of the characters in Kronos Rising come off as rather one dimensional – stereotypes of the genre I suppose. The dialogue, especially some of the innuendo-charged flirtation, made me cringe at times, and the phonetically spelled Jamaican accent didn’t work for me either – it was distracting.

The pliosaur, I noted, only seems to kill men. Perhaps this is some sort of karmic retribution for the monstrous misogynistic acts committed by men against women in this novel? Or, maybe it is simply because there are so few active female characters.

I couldn’t say with certainty where the creature came from in the first place. There are some flash-back scenes to the Late Cretaceous describing how a small population of prehistoric critters came to find themselves enclosed in a caldera during the explosive end to the Mesozoic Era. Incidentally, I should note that the heyday of the apex pliosaur was during the Middle-Late Jurassic and Early Cretaceous, and they became extinct before the end Cretaceous mass extinction event. Nevertheless, exactly how this location and its pliosaur inhabitant remained isolated (under water?) for 65 million years, and the details of the events leading to the release of its occupants into the present day ocean, are unclear. I guess this ambiguity was intentional but it is somewhat unsatisfying. With regard to plot twists I appreciated the tension generated by bringing the combustible mix of characters together in the climax.

In conclusion, this is a novel with obvious echoes of Jaws and Jurassic Park, and it is great to see pliosaurs get the attention they deserve, but I was never completely reeled in by Kronos Rising. There’s surely an audience out there for it, the glowing reviews of Kronos Rising on Amazon.com and elsewhere are testament to that, and indicate that I’m in the minority here! So, pick up a copy and find out for yourself!

Buy Kronos Rising from Amazon.com here
Visit Kronosrising.com
‘Like’ Kronos Rising’s Facebook page

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Written by Adam S. Smith

October 31st, 2014 at 12:03 pm

Book review: Sticks ‘N’ Stones ‘N’ Dinosaur Bones

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“I’ll tell you a story — and some of it’s true —
that explores and explains
what the Bone-Hunters do.”

You’re probably already familiar with the Bone Wars, or the Great Dinosaur Rush, but you won’t have seen this real-life rivalry between two prolific 19th century palaeontologists portrayed quite like this before. Based loosely on historical events, this fanciful version of proceedings, written by Ted Enik, sees both parties in the ‘war’ inventing dinosaur species by the dozen. So, how come I’m reviewing it here? Well, the link may be tenuous, but a plesiosaur makes an appearance at the beginning and end of the book, and that’s all I required to give in to curiosity…

Sticks n Stones

The book opens with a factual introduction that sets the scene, after which, the story takes the form of an engaging Dr Seuss-like poem. The rhyming, rhythmical text is snappy and funny, and at 33 pages long this is a sizeable volume. The story is supplemented on every page with charming stylistic artwork by G.F. Newland. For example, in a preface to the book, we see our plesiosaur restored, and in another early scene, we see our plesiosaur skeleton being unearthed. There’s a passing resemblance of the two main protagonists to their real-world counterparts, O.C. March and E.D Cope, which is surely no coincidence.

Sticks n Stones

Enik states up front that this is a whimsical “take” on events, though it isn’t stated explicitly what is and isn’t made up, so it might be worth saying a few words here to tease out fact from fiction. The story starts off steeped in reality. Our protagonists really did exist, as did the Bone Wars, and the two palaeontologists went to great lengths to outdo each other, as described in the book. However, after this early set up, the story quickly goes off the rails in terms of factual accuracy! While Cope and Marsh might have been liberal when erecting new species, they never made up species out of pure cloth, as happens in Enik’s story. Obviously, Cope did not describe a “NeverTopThisOne-Ginormous-asaurus”, nor did March announce a “WhoAreYouKidding?-Extravaga-saurus”. However, I’ve taken these suggestions on board as possibilities if I ever have an opportunity to name another new species of prehistoric reptile myself! Also, to my knowledge, neither palaeontologist ever used mechanical arms in their digs, though it is a good idea!

Sticks n Stones

The plesiosaur that makes an appearance is, of course, Elasmosaurus, which was pivotal in the real-world Bone Wars. Elasmosaurus was originally reconstructed wrongly by Cope in 1868 with the head on the end of the tail. Despite scrambling to recall all preprints, and despite successfully replacing the erroneous reconstruction with a more accurate one with the head on the right end of the vertebral column, it was all in vain. According to lore, Marsh became aware of the mistake, and swiftly proceeded to place Cope in a headlock and deploy a bout of ‘noogies’ lasting the rest of Cope’s life. Not true (well, perhaps metaphorically so), but Marsh did repeatedly make the most of Cope’s blunder, using it as ammunition in their rivalry and mocking Cope and his “incompetence” at every opportunity. This served to fuel the animosity between the two men, which Jane P. Davidson (2002) has described as “not only a professional rivalry but a genuine hatred of one another”. The story of the Elasmosaurus is so rich and peculiar that I was surprised Enik didn’t make more of it in Sticks ‘n’ Stones. The Elasmosaurus in Enik’s fictional tale is more incidental to the story, a background character portrayed in the artwork, but not referred to in the main prose.

Sticks n Stones

Given the light tone of the book, it would be inappropriate and unfair to cast too critical an eye over the cartoonified Elasmosaurus, so I won’t. Ahh, go on then, I can’t resist, just a little analysis. The swan-necked posture was certainly impossible in all plesiosaurians – the vertebrae don’t articulate that way. The neck is also short by a fair few vertebrae – I count 48 neck vertebrae in one illustration, 28 in another. There were, in fact, no less than 71 neck vertebrae in Elasmosaurus! To go any further with this unjust analysis would be remiss, this is not a text-book, and any book that raises the profile of plesiosaurs and palaeontology in general is good news!

Sticks n Stones

Overall, this is an entertaining and distinctively illustrated romp of a story that I enjoyed thoroughly. I’ll be passing my copy onto my young niece and nephews who, no doubt, will appreciate it just as much as I do.

Available from Amazon.com here and Amazon.co.uk here.

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Written by Adam S. Smith

April 19th, 2014 at 4:24 pm

Book review: Plesiosaur Peril by Daniel Loxton

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In Plesiosaur Peril, author Daniel Loxton plunges us into the Jurassic ocean, to recount a day in the life of a baby Cryptoclidus. The book is the third in Loxton’s ‘Tales of Prehistoric Life’ series, which includes the stories Ankylosaur Attack and Pterosaur Troubles.

Plesiosaur Peril

In this short children’s story we follow a juvenile Cryptoclidus and the rest of her pod as she goes about her daily chores. She seeks some gastroliths, gulps salty sea air, hunts for food, and eventually follows some prey that leads her astray. Of course, this isn’t an ocean paradise free of danger. The villain of the tale is Liopleurodon and our heroine soon finds herself in a perilous situation – you’ll have to get your own copy to discover if curiosity killed the Cryptoclidus!

Plesiosaur Peril

The book is aimed at children aged 8–12 so the paragraphs are short, snappy, and easy to read. There’s a healthy balance between text and imagery, and the visuals, also by Daniel Loxton (with Jim W.W. Smith), illustrate the story beautifully. They consist of a combination of real world photography and computer-generated digital art, which blend almost seamlessly.

Plesiosaur Peril

The fossil remains of Cryptoclidus and Liopleurodon are known from the Oxford Clay Formation of Europe (165 million years ago), so the two species certainly lived alongside each other. It is apparent from the accurate appearance of the plesiosaurs that they were thoroughly researched. Darren Naish is credited in the acknowledgements and presumably takes credit here. The proportions and anatomy are just right, and the same is true for the other prehistoric creatures that show up throughout the story: ichthyosaurs, ammonites, belemnites; all beautifully rendered and well-researched. They are the best I’ve seen in any book of this kind.

Plesiosaur Peril

Quite sensibly, the story itself isn’t bogged down in facts and figures, however, the last page of the book provides some insights into both plesiosaur species for those wishing to dig a little deeper. In particular, this section outlines some of the evidence for the events recounted in the story. Darren Naish has also posted a detailed online article on his Tetrapod Zoology blog, covering some of the behaviour depicted in the book, beating me to it by several weeks! So, instead of covering the same ground, I direct you there.

Plesiosaur Peril

In conclusion this is a lovely and visually striking book that makes the perfect bedtime story for any child with (or without, for that matter) an interest in prehistoric life. I look forward to seeing what the future may hold for the ‘Tales of Prehistoric Life’ series.

Plesiosaur Peril is available from Amazon.com here and Amazon.co.uk here,  and also from Amazon.com via the Plesio-store here.

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Written by Adam S. Smith

April 16th, 2014 at 5:37 pm