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    ‘Anthropomorphisation’ is a good word, and not just because you feel absolutely badass if you manage to spell it right first time. Summed up in those seven syllables is the inherent human condition to project our own sentiments onto other, non-human things. Ever called the weather miserable? Said that a doorway looks menacing? Well done then, folks: you’re keen anthropomorpisers. One of our favourite anthropomorphic acts is to cast roles for animals – it’s like hiring actors for a pantomime. We choose our favourite species and root for them through good times and bad, designate some baddies to boo and hiss at whenever they appear. It’s not always as straightforward as siding with the peaceful herbivores and disliking voracious carnivores: lions are the embodiment of nobility, after all. Robins are garden companions, hyenas are psychotic, carrion eating maniacs, foxes are clever and chimpanzees are clowns. Of course, very often these roles bear little semblance to reality: it’s well known that lions are actually infanticidal, chimps can be almost sadistically violent and hyenas are skilled, practised hunters (and, I should add, have one of the most fascinating vaginas I’ve ever heard of).

    The same thing happens to fossil animals, too. Dinosaurs, being everyone’s favourite extinct critters, are subject to this far more than anything else. Other fossil groups – things like brontotheres, or mosasaurs, say - aren’t given enough screen time to develop real personalities, but every kid in the world knows that Diplodocus is one of the good guys, but harassed by the merciless Allosaurus. Likewise, the armoured stegosaurs and ankylosaurs are goodies too, defending themselves against bullying theropods. I wonder if this attitude comes about because, when you’re four years old and doing the ‘dinosaur thing’ that all children do, the world is very objective and idealistic: things are good or bad, and that’s it. Other kids are either your friend or your enemy, and this is projected onto everyone’s favourite Mesozoic archosaurs. Of course, whatever the reasoning behind it, there is no clearer anthropomorphisation of non-avian dinosaurs than the two late Cretaceous A-listers Tyrannosaurus and Triceratops. Tyrannosaurus epitomises all that can be dangerous in a predatory dinosaur: it’s an enormous killing machine that, I was assured by numerous authors, could hold the eight-year old child reading their words in its open jaws. Triceratops, on the other hand, was the guardian of the dinosaur age. Look at it: it’s got a shield strapped to the back of its head and three spears to ward off enemies with – it’s like a Mesozoic knight. How many pictures are there of herds of Triceratops facing down Tyrannosaurus, protecting their babies with defensive rings of horns and frills? Loads, that’s how many. Triceratops is the nicest dinosaur going, the one we all felt sorry for when it was sick in Jurassic Park and would like to ride to school. What’s more, we don’t have to worry about being eaten by Triceratops - it might be 10 m long, but it only eats plants. Of course, there’s a ‘but’ coming up. If your inner child wishes to preserve this idealistic image of Triceratops and his spiky friends, you may wish to stop reading now. Alternatively, to find out that horned dinosaurs may have had a much darker side to their personality, please read on.

    Y’see, there is good reason to assume that Triceratops and his chums, known as ceratopsians in the business, were not strictly herbivores. There’s two lines of evidence for this: we’ll get to the direct stuff in a moment, but in the meantime we need to check out the business end of ceratopsian ingestion: their jaws.

    One of the most basal ceratopsians we know of is a little critter found in some abundance across Eastern Asia, Psittacosaurus. Its name literally means ‘parrot lizard’, and with good reason: all ceratopsians have a large, deep and very often highly recurved beak, somewhat in the manner of a parrot (this, of course, means that, with one or two exceptions, all ceratopsians have toothless jaw tips). A beaked non-avian dinosaur is not unusual, but ceratopsian beaks are incredibly deep and robust compared to the flattened, spatulate bill of hadrosaurs or the slender croppers of other beaked dinosaurs. Furthermore, despite the immense side of their heads, ceratopsian bills are very, very tapered: nothing like the shovelling mouths of ankylosaurs or hadrosaurs. I don’t think anyone’s ever worked out exactly how strong a ceratopsian bite was, but their beaks seem to indicate that they were capable of producing a decent amount of bite force: certainly the degree of beak curvature produces greater mechanical advantage than a flattened or procumbent beak. Add a sharpened proteinaceous sheath to this, and you’ve got a jaw tip you would not want to stick your hand into.

    Behind this lies a sophisticated and totally unique chewing mechanism. Ceratopsians are one of two dinosaur groups that learnt to properly chew their food, but they have their own unique slant (almost quite literally) to it. Like their fellow masticators, the ornithopods, ceratopsians had constantly-replenishing batteries of teeth lining their jaws, meaning that when worn teeth could be shed and replaced by fresh ones. However, chewing ornithopods have pleurokinetic skulls – that is, the cheek region of the upper jaw can bulge ever so slightly when the lower jaw is adducted, meaning the food between their teeth is ground and torn laterally as they masticate. By contrast, ceratopsian jaws are not pleurokinetic and can only operate in the vertical plane. In fact, the tooth wear on ceratopsian teeth shows that the teeth occluded exactly in this manner. Because their cheek region is absolutely stuffed solid with teeth, their dentition essentially acts like a set of shears, chopping foodstuffs rather than grinding it. This method of mechanical digestion is not seen in any other animal and, as we’ll find out in a moment, is a bit perplexing.

    Operating this battery of food slicing mayhem is a half-decent set of jaw muscles. Now, I should point out that those reconstructions often wheeled out with ceratopsian jaw muscles extending onto their frill are outdated and very likely wrong. The bone surface texture of ceratopsian frills doesn’t show features you’d expect from muscle anchorage and, besides, most of these frills have dirty-big holes in them: you can’t anchor big jaw adductor muscles to nothing but soft-tissue. However, this does not mean the real regions of jaw muscle attachment are anything to be sneezed at: rather, ceratopsians have large, robust coronoid processes (that is, an upright extension of bone on the lower jaw) that would allow for anchorage of big external adductor muscles. Conversely, the sites for anchoring the internal adductor musculature aren’t huge (except for in some basal forms), but the jaw joint certainly is: it’s like the sort of hinge you’d see on a drawbridge. Such a structure would not be needed if ceratopsians had weak, flimsy bites.

    So, the take home message here is that ceratopsians have powerful, shearing bites. Further physical breakdown of foodstuffs would take place in a stone-filled gizzard, as known in Psittacosaurus. But what would they be gizzarding? Well, herein lies the problem. Ceratopsian jaws seem over-engineered for pruning leaves or cropping ferns, and their teeth appear better suited to slicing rigid, fibrous food into chunks than mechanically breaking down cellulose. Whatever they were feeding on, they were selective feeders: their beaks are far too narrow to harvest food en masse. It has been suggested that ceratopsians were connoisseurs of angiosperm trees, dining on fibrous branches as well as leaves and flowers. From the large size of the gut cavities in these animals, it does appear that vegetative matter of some kind made up a reasonable percentage of their diet – plants need big guts to break them down. However, amongst modern animals, the most successful shear-chewers do not eat plants. No sir, they eat meat (lightning flashes, thunder rumbles etc.).

    Yes sir, check out the teeth in your cat or dogs mouth later on: you’ll see they’re perfectly adapted for sliding past each other, scissor-style, for slicing meat into chunks. This presents us with the intriguing possibility that the bizarre dentition of ceratopsians was set-up for a similar purpose and, what’s more, that powerful beak takes on a whole new meaning if you imagine it being used to rip a carcass to pieces. All of a sudden, our Cretaceous crusader is taking on a rather dark image: eating meat involves aggression to get at the spoils, maybe even enough hostility to – shock – kill another animal. Should we risk upsetting generations of kids for this hypothesis? Well, yes, and I’ll tell you why: the stomach content of one Psittacosaurus contains the necessary bones to directly prove it. Alas, I’m short on details of this find – I’ve been after a reference for it for ages and am not sure it’s been published yet – but it’s hard to argue with genuine, bona fide gut content.

    So, rather than placid herbivores, we should imagine ceratopsians – like my Styracosaurus feeding on a small tyrannosaur carcass here (oh, the irony) – as bad-tempered, pig-like animals, shoving other dinosaurs out the way to access carrion, rooting around for small, defenceless vertebrates and maybe, should they come across a wounded, frail hadrosaur, pulling the poor thing apart with their monstrous beaks while it’s still breathing. Of course, plant-matter was probably still on the menu, but maybe as part of a much richer diet. If such a hypothesis is true, this casts a whole new light on ceratopsian skull lesions and pathologies: maybe these fellas had short-tempers when it came to queuing for access to food. It is extremely tempting to compare the horns and graven faces of ceratopsians with the tusked, sculpted skulls of modern pigs, and this is why, folks, I’ve adorned my styracosaur with bristly hair. This does have some basis in reality: Psittacosaurus (again) fossils have shown that at least some ceratopsians had long, bristly barbules lining the tail. Hence, I figured if they could grow on the tail, why not stick them across the face, neck and shoulders? Don’t get me wrong – I know skin impressions of large ceratopsians show they had scaled, leathery skin, but, well, consider it artistic licensing.

    So, brutish, omnivorous ceratopsians, then – undeniably controversial, but surely quite possible. I’m not sure if this idea is out in the technical literature yet (I certainly haven’t seen anything on it), but it’d be interesting to see what the palaeontological community makes of it. The idea of pleasant, herbivorous ceratopsians is just as entrenched in professional palaeontology at it is in kids books, so it could be rejected outright on the basis that we’ve known what ceratopsians ate for years. Personally, I find the idea of ceratopsians acting like giant boars far more interesting than them standing around chewing trees, but that’s just me. Anyway, to anyone daft enough to still be reading (well done if you are), seeing as I’ve nearly hit three pages and the clock almost reads midnight, I think I’d best stop there. Good night, folks. Don’t have three-horned nightmares.

    sandrino, BlowedUPtruck, dananddna, and 35 other people added this photo to their favorites.

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    1. Mark Witton 84 months ago | reply

      Cheers Mike. Yes, the tyrannosaur should also be fuzzy and this did cross my mind as I was drawing the image. However, I recall that tyrannosaur skin impressions show bigger individuals had scaly skin, so I thought I'd follow that line of reasoning. As this picture attempts to show ceratopsians in a different light, I thought I could make a bigger splash by being more adventurous with the Styracosaurus integument. It's funny that, nowadays, it's more controversial to draw a coelurosaur without feathers than it is to draw a feathered one - how times change, eh?

      Anyway, thanks for the comment. I would definitely like to see this idea discussed and tested properly - I certainly think the idea is compelling enough to warrant proper investigation. Although ceratopsian jaw mechanics have been looked at in the past, maybe a fresh approach with FEA and other high-faultin' computer wizardy could shed some new light on their bite forces and stress distribution. This might tell us, as their jaw morphology seems to suggest, whether or not their jaws really are overengineered for simply pulling plants apart. Here's hoping, anyway.

    2. MichaelPTaylor 84 months ago | reply

      Mark, first off, nice work. Second, you are a loon to waste these thoughts on something as transient as comments on a Flickr image. You should definitely write this up properly and push it out to a journal.

    3. Mark Witton 84 months ago | reply

      Thanks, that's very kind of you. I really would like to publish on things like this but am not sure about the right venue. Because of the lack of testing, I doubt most technical publications would be interested, but the subject matter seems a bit too specific for most general geology magazines: most general readers aren't too fussed over the size of the ceratopsian coronoid process, after all. Hence, I'm trapped in an empty, publication-less limbo. Any recommendations or suggestions?

    4. nickgardner 84 months ago | reply

      Because of the lack of testing, I doubt most technical publications would be interested, but the subject matter seems a bit too specific for most general geology magazines: most general readers aren't too fussed over the size of the ceratopsian coronoid process, after all. Hence, I'm trapped in an empty, publication-less limbo. Any recommendations or suggestions?


      Consider writing a trade article for this publication. What you have described above seems appropriate for this venue, no?

    5. Neil Phillips 84 months ago | reply

      How does the beak compare to skulls of raptors, vultures, owls etc? Or even to squid/octopus beaks? these are all used to rip flesh. I like the logic behind your reasoning - as much as it shatters one of the few things I learnt about dinosaurs as a child that have since been prove wrong! I can see Cerotopsids eating carrion no problem, and when you look at the paper released today about T. Rex 'definetely' being a scavenger you can imagine T.rex and Triceratops fighting over a carcass rather than protection of young!

    6. MichaelPTaylor 84 months ago | reply

      Mark, I think you should not worry too much about the "lack of testing": you can make your case well using comparative figures, showing how the ceratopsian skull is similar and dissimilar to known carnivores and herbivores. You might also throw in a back-of-the-envelope calculation regarding the relative bite pressures (not forces) of, say, Triceratops and Edmontosaurus. I don't see any reason a technical journal wouldn't take that if you do it convincingly. In any case, the ceratopsian beak certainly looks way over-engineered for a black rhino analogue.

    7. Mark Witton 84 months ago | reply

      Neil: Raptor beaks certainly share broad characters with those of ceratopsians. Both tend to be deep and narrow with recurved ends, but these characters are unsurprisingly far more developed in raptorial and scavenging birds than they are horned dinosaurs. Ceratopsian beaks aren't quite as recurved as those of predatory birds for one thing, though they appear relatively deeper. However, just like raptors, the ceratopsian mandible is overbitten by the beak. Presumably, this allows for terrific grip on soft foodstuffs, like big, bushy plants or meat: the convoluted apprehension pattern produced by a staggered gripping system won’t remove a nice, neat chunk of food like our incisor-based single-point bite system will, but you’d have a had time pulling that food out of the closed ceratopsian beak. Hence, combined with a bit of pulling and twisting, ceratopsian beaks could no doubt be used to wrench meat from a carcass just as well as pulling Mesozoic hedgerows to pieces. This is my take-home interpretation of ceratopsian beaks: because they appear so robust, suited to strongly gripping masses of soft food and, ultimately, distinct from the beaks and jaws of other herbivores, the question of omnivory changes from why omnivory to why not omnivory?

      Mike and alkalynic: Thanks to you two, I’m now giving serious thought to writing this up properly (and to think, it all started as a way to pass the time during hours of exam invigilation). Cuh. Hope you’re happy.

      Seriously, if you reckon there’s scope for publication with this, I’ll give it a go. I’ll decide on a venue when I’ve got something more concrete together. It might take a while with both a PhD and silly, nagging ‘real life’ issues to contend with, but, well, it’ll give me something to write about in the evenings that’s a change from big, leathery winged reptiles. Thanks for the support guys, and watch this space, I suppose.

    8. Rich Butler 83 months ago | reply

      Some more details about the psittacosaur stomach contents would be useful. All the psittacosaur stomach contents I'm aware of are gastoliths, which are highly suggestive of herbivory (as is the propalinal jaw mechanism - also seen in other basal ceratopsians - and the morphology of the wear facets). Are you sure you're not confusing this with the discovery of juvenile Psittacosaurus bones in the mammal Repenomamus?
      Richard Butler

    9. Mark Witton 83 months ago | reply

      Hi Richard,

      I must confess, the bony stomach content of psittacosaurs is, I'm afraid, little more than a rumour that I hope to hear more about in a peer-reviewed publication soon. It has been known for some time - Luis Rey illustrated his version of Psittacosaurus omnivory back in the late 1990’s and a few other mentions of its are to be found scattered across the internet. My best source for it is Darren Naish, who started this whole ball rolling a few years back while we discussed ceratopsian jaws in front of a Triceratops skeleton.

      I guess we could take the absence of reputable reports on this as a sign that someone made a mistake interpreting the gut content, but it seems equally likely that this is just one more important specimen awaiting description on someone's shelf. There does seem to be an ethos nowadays among Chinese workers that nothing but feathered theropods will reach the press, so I fear the latter theory could be the awful truth. I mean, have you seen the new coffee table book, The Jehol Biota? Pages on pages of theropods, and about four on all ornithischians, including psittacosaurs with soft-tissues and the world's smallest ankylosaur - it really boggles the mind. Whether someone has just started a rumour that they wish would go away or I'm just paranoid, It certainly would be nice to know the real story on this one.

    10. Rich Butler 83 months ago | reply

      Thanks for the additional information Mark. I must admit that, seeing as the paper hasn't appeared, I remain skeptical. More papers are published on the Chinese theropods than ornithischians; however, new psittacosaurid species and specimens from the Yixian and elsewhere are being published upon on a regular basis, and I struggle to believe that the Chinese would neglect this (an easy mid-ranking - Proceedings B or similar - publication).

    11. felynz 80 months ago | reply

      Beautiful artwork! I've always thought that ceratopsians were probably omnivorous, like pigs or peccaries, but I have not seen that POV expressed in print before. What an insightful, informative article this is!

      I always laugh when I read some simplistic nonsense like "Oh, don't worry, they won't hurt you, they are PLANT EATERS". HELLO? Ever heard of rhinos? Hippos? Buffaloes? Domestic bull, for chrissakes? Some of the mosy truculent and aggressive animals alive today are herbivores, and many herbivores are eager to consume carrion. There are many species of suids today, which fill a niche for an agile, aggressive, intelligent, social omnivore. Why would there not have been such animals during the Mesozoic?

      I love your artwork, Mark. You really bring these creatures to life.

    12. Nentuaby 76 months ago | reply

      I've always wondered why even the classical herbivorous ceratopsian is considered so cuddly.

      Have you EVER met a sweet-tempered large herbivore? No. Excepting the dairy cow (which is bred to be, simply put, mentally retarded), they're all pugnacious brutes. From the elephant in must to the surly yak to the dreaded hippopotamus, they'll gore you to death even if they won't eat you.

      And the ceratopsians DO look a lot more like a pig analogue than a full time flower eater.

    13. Mark Witton 76 months ago | reply

      (Somewhat belatedly), felynz: thanks for your nice words about the pictures.

      felynz and Nentuaby: couldn't agree with you more.

    14. GWolf707 66 months ago | reply

      Hmmm. Interesting...you do like to cause trouble don't ya Mark :D

      What does it say about me though that I find the quills more interesting than the omnivourousness...ness.

      Also, (forgive me if this got mentioned, only skimmed thorugh due to time) there is a precedent these days with hippos. We've thought of them as pure herbivours for years, now we have evidence not only of them scavenging, both from other species and dead hippos, but I believe I heard about a hippo being sighted attacking a gazelle, or a gnu or something. So it wouldn't be like this were the only time we missed out on something like this

    15. Mnynames 65 months ago | reply

      Let me start by saying you do absolutely fabulous artwork, apparently I've been snatching them up for some time when they appear with various online articles, never knowing the origin.

      I don't know about you, but where I went to school, it was the T. rex who was the hero dino that everyone wanted to either be or ride to school on...perhaps I just ran with a tougher crowd, or it's something to do with the typical American mentality, I dunno. Personally, this was one of the few instances where I sided with the herbivores, as Triceratops was always my favourite. Well, Pentaceratops was, actually, but most other kids didn't know what that was, so I usually just said Triceratops. That said, I also always felt that straddling a Triceratops neck as one sees depicted from time to time would very quickly result in being squished by that massive crest the first time the poor beast looker up. I'd advise a howdah...they certainly were big enough for one. (Nowadays, I think my ideal dino mount would be a robust Ornithomimid like Dromiceomimus, as I think they'd be faster and more agile. Last I checked though, no one is quite sure what they ate, with most suggesting some form of omnivory).

      Personally, I never thought of Ceratopsians as particularly cuddly, as they seemed like Saurian Rhinoceros analogs to me, and we all know how pugnacious they can be. Someone else has already mentioned the aggressiveness and carrion-eating tendencies of the Hippo, which certainly seem applicable, but even the half-lobotomized Cow is on record as killing animals and consuming flesh (Often other farm animals, like chickens and ducklings). Deer too, have been observed hunting and killing small animals such as Rodents and Lizards, although it is far from common behaviour.

      Your words here have been some of the most fascinating I have read regarding dinosaur behaviour in a very long time, and frankly, they just make me think Ceratopsians are even cooler than I had previously imagined. Keep it coming!

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    19. cavenewt 5 months ago | reply

      It occurs to me that ripping flesh from a carcass would also have requirements for a certain amount of flexibility in the neck department. Has anyone ever considered that?

    20. Atarah Derek 4 months ago | reply

      Hippos eat carrion. Why shouldn't other large animals traditionally seen as herbivores? Grass alone is not necessarily enough to sustain that bulk, especially for an animal that is naturally quite aggressive, which a ceratops likely was, given their need for horns. Carrion provides a good protein source that's not prone to running away, and when you're that big, smaller, more traditional scavengers aren't inclined to interrupt your dinner.

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