Why should everything be made to look like insane escapades?

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    Typically, pictures that I draw are posted on this here medium pretty quickly after they’re finished, sometimes in such a flurry of activity that I later feel the urge to remove them, finish them properly, and upload them again. Not so with this image: this one has been lurking on my hard drive since April, waiting for an embargo lifted only hours ago before it could be revealed to the rest of the world. Yes folks, I’m pleased to announce that this is another press release image drawn to illustrate the findings of a brand spanking new scientific paper. Although my pictures are slowly trickling into other publications, this is only the second picture I’ve drawn to order. It accompanies a new paper in PLoS Biology (synopsis here) that presents findings of biomechanical and anatomical research that suggests pterosaurs could not skim-feed in the manner of the skimming bird, Rynchops. This idea is pretty entrenched in pterosaur literature and certainly needed some serious testing given that, as we’ll find out in a minute, it’s quite a bold claim that should’ve raised eyebrows a long time ago. As such, it was only relatively recently that Stuart Humphries of the University of Sheffield, Richard Bonser (University of Reading) and Dave Martill (University of Portsmouth) finally addressed the issue head on. I should point out that these chaps were not alone in their studies: there’s one more author on this paper, too. It might be early hours of the day, but please pop the corks from the Champagne and raise your glasses to toast what for me is a most momentous day: Mark P. Witton is now, officially, joint author of a technical, peer-reviewed publication. What’s more, I can proudly proclaim a reasonable chunk of the manuscript was researched and penned by myself, so my name has not been stuck on there to commemorate my making of coffee whilst real scientists did the hard work. Furthermore, PloS Biology has the highest readership of any biology journal in the world and several press agencies have been in contact with me and the rest of the team to write their own pieces on it, so it’s not turning out to be a bad entry into the world of technical publications. Time will tell how far our story runs, but for the time being, words fail to really sum up just how excited this makes me. I suppose, in case you can’t tell, it will suffice to say that I am very, very happy about this.

    But that’s enough self indulgence: what of the paper itself? Well, the story of this project has a bit of a prologue, beginning way back in 2002 with the publication of the pterosaur Thalassodromeus. This enormous Brazilian pterosaur has a peculiar, apparently laterally compressed jaw that was suggestive to its describers of a ‘skimming’ lifestyle. ‘Skimming’ is a highly specialised foraging technique employed by a group of birds imaginatively titled ‘skimmers’, or Rynchops in scientific circles. Skimmers feed by flying extraordinarily close to the water surface with their lower jaws (mandibles) trawling through the water to catch any prey items they may strike. They tend to do this in shallow waters around marshes and estuaries to concentrate their prey into a shallower water column, and you can expect a skimmer to snag a morsel of food every five minutes or so. This feeding method is pretty much unique to skimmers, with only the closely related terns showing any other skimming behaviour on occasion. You may justifiably wonder why this is, and the apparent answer is that skimming is more difficult than it looks. In order to compensate for the tremendous drag and impact forces that occur in skim-feeding, Rynchops has evolved a hyper-thin, knife-like mandible for cutting through the water, additional bracing around the jaw joint to prevent jaw disarticulation during skimming impacts and ultra-robust neck anatomy for the same purpose. Bear in mind that catching relatively small prey on constitutes a proportion of skimming impacts: skimmers also snag submerged obstacles and substrata that can wipe them out of the air and snap their beaks. For this reason, skimmers have extra-long extensions of their mandibular beaks formed from quickly regenerating soft tissues to allow snapping of their bill tips. As feeding strategies go then, skimming is up there with eating McDonalds food in not being for the faint hearted.

    It is perhaps surprising, then, that the workers behind Thalassodromeus should have proposed skimming as a lifestyle for their sexy new pterosaur. In fact, these chaps went as far as to name their beast ‘ocean runner’ in Latin in reference to its supposed lifestyle. A look into the history of pterosaur research reveals that this was only the latest in a long line of proposed pterosaurian skimmers: as early as 1912, folk were proposing that Rhamphorhynchus was a skimmer, with Pteranodon, ornithocheirids, dsungaripterids and even the giant azhdarchids all postulated as skimmers by the turn of the millennium. Thalassodromeus, therefore, was merely one more form on the skimming bonfire, but one that, with a supposedly-knife like mandibular tip, was far more likely than the other postulated skimmers. However, the skimming hypothesis already smells a rotten here: as animals become bigger and heavier, flight becomes more costly. Some of these proposed skimmers were huge – could they really provide enough muscle to, erm… muscle their way against all those skimming forces?

    These were the questions that Stu, Richard and Dave set out to answer. At this very early stage, I was still finishing my degree and the plans for the experiment were set out to my total ignorance. Hence, by the time I was first introduced to Stu and Richard (I knew Dave already, being my thesis supervisor and all) in the first few weeks of my PhD back in 2005, some trial runs of the experiment had already been run. Stu, Dave and Richard had come up with the idea of testing the skimming capabilities of pterosaurs by literally pulling mock-ups of their jaws through water down a 10 m flume tank housed at the University of Portsmouth. We had two pterosaur jaws to test, that of the purported skimmer Thalassodromeus, the non-skimmer Tupuxuara and the mandible of Rynchops for comparative purposes. The jaws were underslung from a trolley that ran along the top of the tank, itself pulled along by a motorised winch at the tank end operated by Stu. Gathering all our data was a stress sensor recording the forces experienced by a 3 mm thick aluminium bar connecting the jaw tip to the trolley during the towing. It all sounds pretty slick, and it was, save for the fact that 10 m was enough distance to get the jaws up to speeds of 25 kmph (or almost 16 mph for those who refuse to go Metric), but not enough to slow it down. Hence, some poor sod had to stand on a ladder to catch the screaming hell-banshee that was the skimming dolly or else it, and all the paraphernalia and models it was carrying, would shoot off the edge of the tank into a rather expensive disaster on the floor. The day I met the skimming team also marked the first day of testing, and Dave and I took it in turns to do act as catcher for the dolly. All was going relatively well, with good data recorded for Rynchops and Tupuxuara, and then, as I climbed the ladder for my turn, Thalassodromeus, the ocean runner itself, was loaded onto the trolley.

    In all the press accompanying the publication of Thalassodromeus, one worker is recorded as saying it must’ve looked like a ‘vision of hell’. Well, hats off to him: he was right. There was something unerringly terrifying about the massive jaw tip of this thing hurtling towards you at great speed. Maybe it’s because there was water everywhere. The moment Thalassodromeus began to skim, the whole rig started shaking manically, throwing water about like a possessed jetski and drawing worried glances from the crew. Notching the speed higher, the rig became more unstable and, to everyone’s surprise, the aluminium bar was even bent on one run. This was replaced and, eventually, the time came to set max speed: 25 kmph. The catcher, a nervous looking PhD student, was braced and ready. At the other end of the flume, the pterosaur-cyborg beast glared at him, the water eerily calm before the violence that would follow. “You ready?” asked Stu, and I gulped my affirmative. The winch was pulled. Suddenly, the beast was roaring down the runway. The room echoed with the inhuman screaming of its wheels on the track. The jaw was convulsing madly. Water crashed over the tank walls. Then the screaming stopped with a loud bang: the Thalassodromeus was airborne; the whole rig arcing through the air and spiralling forward - only milliseconds seperated it from a watery grave. My clothes ripping against the metal tank and the waves pounding my body like Achilles in the River Scamander, I leapt forward and grabbed the plummeting contraption moments before it hit the water. We rushed the wounded rig from the flume to check its health: the aluminium bar was totally twisted, the electronics shot. The little blinking lights on the mechoreceptor faded to black. The rig lay dead in Richard’s arms. Stu called to the Heavens in anger. Dave cried. I was soaking wet. It was about then that we started wondering if ‘ocean runner’ was a name slightly too optimistic about the skimming capabilities of its owner. With testing brought to a dramatic but premature end for the day, we retired for back massages and herbal treatments from attractive Scandinavians to recover from the ordeal. Such is the life of courageous university researchers.

    The second day of testing (actually a number of weeks later) went by pretty smoothly, and it wasn’t long before we had enough data to call a halt to the testing and start work on the manuscript. It was about this time that the idea occurred to us that we should also check out pterosaur skulls – after all, if Rynchops is so specialised for its skimming lifestyle, we should see similar traces of specialisation in pterosaur skimmers, right? So, while Stu and Richard crunched the numbers obtained from our fluming exercises, I went to work looking into the skimming adaptations of a whole bunch of pterosaurs. First and foremost, the shapes of pterosaur bills: turns out that not one, even Thalassodromeus has a bill even remotely like the razor-thin bill of Rynchops. Granted, Thalassodromeus has a tapered upper margin on its mandible like those of skimmers, but its mandibular tip is still incredibly fat – with all the drag this would produce, it’s no surprise it shook itself to pieces in the flume. Jaw joints were next: any adaptations to withstanding impact forces? Uh, no. Pterosaur jaws are really pretty flimsy – more like those of non-skimming birds than the doubly reinforced jaw of Rynchops. Necks? Also nothing special, although Thalassodromeus and Tupuxuara score points for being more flexible than most. Long-necked azhdarchids, by contrast, would’ve snapped their necks the moment they skimmed anything with more resistance than snot, and that’s probably enough to shoot their skimming prospects down on its own. As it was, while I was buried in books the results from the number crunching came back: turns out that Thalassodromeus and Tupuxuara were on the wrong side of the graph to be skimmers, whilst Rynchops was comfortably the right neck of the woods – er, marsh – to skim happily (lucky for us, really – it’d be a bit embarrassing if we proved that skimmers couldn’t skim). What we’d found was basically a problem of scaling: the bigger pterosaurs, in association with their relatively broad jaw tips, appear to have had insufficient energetics to both flap their wings – even incorporating some gliding into the equation – and skim at the same time. Interestingly, our modelling suggests that skimming is even more energetically demanding than it appears for Rynchops, highlighting the necessity for that blade-like bill to reduce drag. Using the mandible of Tupuxuara as a model, Stu then played around with some bigger pterosaurs: the 6 m Pteranodon and 10 m Quetzalcoatlus, both of which have been postulated as skimmers at one point or another. Neither made the grade, especially when we (just to cover our backs) extended their mass estimates from ‘consensus figures’ to the highest published mass figures out there. Conversely, our model suggested that small pterosaurs might be able to skim with the right equipment, but, as no known pterosaurs appear satisfactorily geared in this respect, we feel pretty damn confident in saying that no pterosaurs were regular skimmers. In fact, based on their jaw morphology alone, I’ve been wondering how the idea gained any following in the first place. Why do people latch onto these ideas when all the evidence is to the contrary? How do these proposals ever get through peer review to begin with? Mind you, I’m sure lots of people would say the same thing about many of my proposed pterosaur ecologies, so I shouldn’t get too high on this soap box. I just figure that some ideas about ancient animals are a bit too larger than life and could really do with more thought before publication. This is not to criticise people coming up with new hypotheses of course – I just think that suggestions of this nature should be mulled over, researched and tested more before they’re released to the world, s’all. I’ll stop ranting now.

    Even once we knew what we wanted to say, it took a long time to get this paper together. At one point, we had a pretty major re-write after several reviewers suggested the initial submission was overly brief. If one thing’s become apparent since I started all this academic stuff, it’s how long everything takes. Other projects turn up, personal commitments take you out of the loop for a while, silly pieces of bureaucracy suck your time away… It all conspires to push projects like this on and on, and it’s nearly been two years since the first run in the flume tank. Still, it’s all been worth it: a neat little paper that I hope will be well accepted, a place in a top journal, lots of press interest and the promise of being on Radio Four this Thursday (21:00, 26/07/07, pterosaur fans). Plus, and most happily for me I suppose, there’s another press image to put on my C.V. This was an interesting picture to draw, actually: there are pictures a-plenty of skimming pterosaurs, but we naturally didn’t want to show this as it conflicts with our findings. Problem is, how do you draw a pterosaur not skimming? All right, that has a rather obvious answer, but how can you show a pterosaur not skimming meaningfully? You know, to make the point that it can’t and all? The answer came to me from bitter personal experience: school discos. As anyone who’s ever met me will know, I am not really the dancing type. No, I can’t get funky for love nor money, and I’ve never been able to. Hence, while all the fun and excitement was going on at school dances, I tended to sit on the side, watching the spinning, dancing and twirling of my chums as I sucked on a Coke and waited for home time. Nothing quite says ‘I can’t dance’ more than a guy sitting on his own at the side of the dancehall, so I figured nothing would say ‘I can’t skim’ more than Thalassodromeus, the fallen wave-runner, sitting on a riverbank whilst Rynchops, having the time of his life, whizzes by in a skimming frenzy. Although I’m pretty happy with it, I’m especially glad that Rynchops has come out all right: it’s rare that I draw anything from modern times that you can directly compare the real McCoy, so the fact that it looks pretty Rynchops-like is a relief.

    And on that note, I’ll finish. All that’s left is to thank Stu, Richard and Dave for inviting me in on the project and congratulate anyone still reading this marathon essay – this is the longest post on this site by a long way. As always, thanks for reading.

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    1. Mark Witton 82 months ago | reply

      The 'Thalassodromeus flume of doom incident'?

      Brilliant.

    2. Richard Hing 82 months ago | reply

      “As anyone who’s ever met me will know, I am not really the dancing type. No, I can’t get funky for love nor money, and I’ve never been able to.”

      I’ve met him, and I can vouch for the fact that Mark can and will dance, even if it takes three years to get him in the mood, and not only that but he does a mean Mick Jagger impersonation at karaoke.

    3. Darren Naish 82 months ago | reply

      The 'Thalassodromeus flume of doom incident'?

      When I get round to writing a blog post, that'll be the title.

    4. Neil Phillips 82 months ago | reply

      I have to say that was a rather enjoyable read. Iwas actaully on your facebook and say the thing flash up when i refreshed the page! but I got called away half way through reading this. Congrats on being published and i think the, as Darren put it the 'Thalassodromeus flume of doom incident' (good stuff!), is going to be one of those stories that everyone will hear

    5. Neil Phillips 82 months ago | reply

      Also I should say I knew it was a skimmer striaght away and its a very good drawing of one, but then I'd expect no less from you

    6. Kimhotep 82 months ago | reply

      Congratulations! Fascinating findings. Poor Jiffy, I suppose his fancy schnozz will be chalked up as a sexual display, then.

      Have there been any photos of the skimming experiment setup? Very Mythbusters-esque, and I am impressed there were no spontaneous explosions. I did actually LOL at your success in finding that skimming birds can in fact be scientifically proven capable of skimming. Very fortunate indeed! Perhaps now you can address those pesky bumblebees who supposedly can't support their own weight in flight.

      I like to assume that your middle initial does in fact stand for 'Pterry'.

    7. Mark Witton 82 months ago | reply

      Thanks for all the nice comments. Hopefully, the 'flume of doom' story will become the stuff of palaeontological legend - we should've made something of it in the press releases.

      "I am impressed there were no spontaneous explosions".

      We tried our best, but the splashing water really made it difficult to keep the powder dry. As for photos, We did video the runs to calculate veolocity, but I don't think we took any photos. I have mocked up a little diagram that I was going to use in a talk, but it's not quite the same.

      "I like to assume that your middle initial does in fact stand for 'Pterry'."

      If it didn't before, it almost certainly will now.

    8. sandrino 82 months ago | reply

      Congratulations Mark!

    9. Microecos 82 months ago | reply

      Awesome illustration. I would expect T-drome to be wistful about that skimmer but he seems perfectly Zen. Thanks for helping us figure out these improbable fliers!

      You should upload that video, flume of doom could be a big winner on YouTube.

    10. Neil Phillips 77 months ago | reply

      Hi, I'm an admin for a group called The David Attenborough group, and we'd love to have your photo added to the group.

    11. Peryton 77 months ago | reply

      He seems to be sad for not being able to skim

    12. dorat2008 76 months ago | reply

      Dear Mark

      This is to ask you if I can use this great image in order to participate in an Athens video art festival. My video visualizes an ecological fairytale I wrote in Greek that I also narrate. I think that art owes to be concerned with the key issues of our age, like environmental pollution and has to also keep us all concerned with such issues. The images I used and yours among these are a hymn to life and to our planet (it also has to do with Adam and Eve and a new paradise) . In the introduction to the video I say that:
      the following video includes images from www.flickr.com (artist’s names), in order to visualize my story. There is no relation between the artists’ original intentions and my use of their images. The present use is exclusively for artistic, non-commercial purposes.
      Also, in the end there is detailed mentioning of the sites from which the images were taken. Please accept my many thanks to you as an artist. I consider you a co-creator of this video.

      Yours,
      Dora

      p.s.My account doesn't allow me to send more than ten messages, so this is the only way to contact you.

    13. the mad LOLscientist 72 months ago | reply

      =LOL= I almost can't look at a pterodactyl without thinking of the airliners on The Flintstones. The pilot of this model must have had a hell of a time landing it in a crosswind! (Of course it doesn't help that any illustration of a pterry on the ground looks like the thing has crashed.)

      Congratulations! Oh, and disco itself may not be dead (dammit!), but it sure killed a lot of us!

      ROFLingMAO @ "Thalassodromeus flume of doom incident"

    14. patrickdodds1 70 months ago | reply

      You are invited to display your image.
      Who You Lookin' At?
      Better Than Good
      Invitation Only

      If you accept this Invitation,
      please give awards to other images.

    15. David_from_St._Louis 69 months ago | reply

      Mark,

      Just being a good scientist (aka: a fly in the ointment), a few questions and comments come to mind:

      1. I'm impressed by the similarity of the cross-sections of Rynchops and Thalassodromeus. Any comments on that, especially noting the change in Thalassodromeus with regard to its close relative, Tupuxuara? It looks, at least, as if Th. was _trying_ to be a good skimmer. : )

      2. As I recall, and you note, the tip of the rostrum and mandible in Thalassodromeus was broken off and lost, so any reconstruction is a a matter of guesswork. Right? Did you try alternate reconstructions to cover more possibilities?

      3. Airspeed only equals waterspeed when airspeed (wind) is zero. Since there is often a breeze at shorelines, feeding strategies could have employed skimming upwind, thus reducing waterspeed down to acceptable (less splashy) ranges. Why was this not considered in your conclusion?

      4. In some pterosaurs it was not likely the lower jaws that were designed for skimming, but the upper ones, which, in the case of the Triebold specimen of Pteranodon, is much longer than the lowers. Both of which, by the way were needle sharp. Were any upper jaws tested for pterosaurs?

      6. And lastly, if they couldn't skim with those needle-sharp beaks, what do you suppose they did for their supper?

      David Peters

    16. Mark Witton 69 months ago | reply

      Hi Dave,

      Here's my proverbial fingers trying to remove the fly from the ointment:

      1) Um, are we looking at the same cross-sections? Thalassodromeus has a big, chunky mandibular symphysis about half-as-wide as it is tall: Rynchops has something more far more blade-like, maybe one-fifth or sixth of it's height. All right, they're both tapered along the occlusal surface, but they're in different leagues when it comes to streamlining.

      2) Happily for us, Veldmeijer et al. (2005) described a complete Thalassodromeus mandibular symphysis. We used a cast of this as the basis for our reconstruction, so we're pretty confident that we got it right.

      3) There is often a breeze at shorelines, but not always (I've spent countless hours walking the Portsmouth coastline of late, so feel quite confident in saying this). I think Jim Cunningham has a similar model proposed for skim-feeding azhdarchids (although note that these critters, what with mainly living inland and all, dwell in even more wind-variable settings than pterosaurs hanging around the beach). Ignoring that for the sake of argument, if you check out the graphs in our paper you'll see that any pterosaur with a wingspan over 2 m is really going to struggle work up the energy to skim, so you'd need the sort of thing worrying New Orleans at the moment to make this idea work.

      As a rule, I find these ideas of wind-related pterosaur habits hard to swallow: you know, they could only take-off with wind, they could only feed with wind, etc. I think they reek of special pleading, a way of trying to shoehorn a lack of understanding of pterosaur palaeobiology into a shoe that really doesn't fit. Luckily, folks like Jim and Mike Habib have approached things like pterosaur launching with fresh eyes and found ways to get sensibly ladened pterosaurs into the air without the remotest hint of a breeze. The same approach is needed with foraging strategies: I think if the biomechanical evidence and, more importantly, anatomical evidence is really against an idea (as is the case with skim-feeding), using things like local weather conditions to try to prop said idea up is really scraping the bottom of the barrel. I'm not saying you don't have a valid point about windspeed and all that - I'm sure it would help a hypothetical skim-feeding pterosaur - but for the time being, there's not a scrap of anatomical evidence to suggest that pterosaurs skim-fed in the first place, so it's a moot point.

      4) I'm confused: how are the premaxillae meant to play a role in skim-feeding? Surely an animal skimming the water with it's upper jaw would just bump food out of the way? Skim-feeding is done with the mandible so the upper-jaw can clamp down the moment anything edible is detected: so far as I can see, you can't skim-feed with your upper jaw.

      5) Um... pass. Well, sort of. We have an idea what Pteranodon was eating: tiny little fish. I guess that makes sense: thin, slender jaws - small prey items. How it was getting them I'm not so sure, though. I'm not convinced about dip-feeding: it's lacking dip-feeding adaptations in its jaws and neck. As for Thalassodromeus, again, I'm not really sure. It's got a pretty robust(-ish) skull, so maybe it was going for comparatively big but sort-of squishy or slippery prey items (little soggy vertebrates? bars of soap?). That might explain its tapered occlusal margins: lots of pressure put on one point. It has no means to process food to speak of, so it's clearly not grabbing shellfish like Dsungaripterus probably was with its occlusally-tapered jaw tips. So, whatever it was gabbing, it was swallowed as it was taken. Beyond that, I don't really know: we're totally lacking postcrania for this chap, so the conservative, boring thing to do is wait for more material to turn up. I hope that's not a cop-out: Pteranodon would probably spill its foraging secrets if poked enough, but for virtually-unknown animals like Thalassodromeus, I think we have to be manly enough to admit that there's just not enough information to work with for the time being.

    17. David_from_St._Louis 68 months ago | reply

      Mark,

      I appreciate your comments. Bottom line is this: if Pteranodon and Rhamphorhynchus were found with fish in their bellies, there were only two possibilities as to how they got there. I'm sure they didn't volunteer. So, now, how do these pterosaurs get the fish? Again two possibilities.Did they sit and wait on the surface? Or did they actively pursue?

      You mentioned both were tapered on top, but in different leagues with regard to streamlining. Some of the reasons why early airplanes went from two thin wings to one thick wing was added strength without much of an increase in drag. Consider the scale difference between a skimmer and a giant pterosaur!

      Please send images of the Veldmeijer et al. 2005 mandible. I could not find it on the web.

      As long as their is often a breeze at shoreline, there need not be one all the time. Pterosaurs would call the breezy times "breakfast and dinner" and the none breezy times, rest. I'm not one to pretend that pterosaurs needed a breeze to fly, but if waterspeed is the deciding factor here, that can be eliminated by choosing a specific dinner time. This is not, in most circles, considered "scraping the bottom of the barrel."

      To that point, Mike Habib and I are having discussions on hovering pterosaurs. We have evidence for a two-point touchdown, so galloping, hurdling takeoffs and breezy days may not have been necessary in either case.

      With regard to your confusion regarding skim fishing with the longer, sharper, premaxilla, as in Rhamphorhynchus and Pteranodon: there are examples among birds of spear-fishing. The Anhinga targets slower-moving species of fish and stalks them underwater, finally striking out with its long neck and spearing the prey with its beak. It then brings the prey above water and jerks it off its bill, manipulating it in order to swallow the fish head first. Not saying pterosaurs went underwater. It just shows how a sharp beak can work.

      Finally, the post-crania of Thalassodromeus cannot be too far removed from that of its sister taxa, which are well known.

    18. Mark Witton 68 months ago | reply

      Regarding bill thickness: the Thalassodromeus jaw is simply a really naff hydrofoil. It's entirely the wrong shape in cross section, more akin to a slightly lopsided diamond than a blade. Check out this image in our paper: the two are really nothing alike. I see your point about mandible strength and all, but maybe there's a pretty low limit on the maximum size a skim-feeding animal can get before skim-feeding flight costs outweigh power available?

      Again, with wind and shorelines: for the last week-or-so in Portsmouth we've had nothing but howling gales, and I think there's a similar situation all around the country. It's like walking around one of those new sexy Dyson hand-driers I like playing with in public loos. There's been virtually no let-up at all, so how would a wind-dependent feeder deal with days and days of violent winds that could impinge flying? In my experience, lots of birds will just sit out truly horrendous conditions, squatting down with their bodies aligned to the prevailing wind direction. After all, there's no point trying to fly if you simply get blown off course the moment you take into the air. Similarly, days and days can pass when there's virtually no breeze at all, even at the coast. How would a wind-dependent feeder cope with this? Pterosaurs probably had high metabolisms, so probably needed to refuel regularly: I find it difficult to see how they (and particularly smaller critters like Rhamphorhynchus would cope with several days without feeding. I could be wrong, but I don't know of any animals that are so tied to weather conditions for feeding. That's not to say that animals are not climate dependent - we all are, to greater or lesser degrees, but climate is not as fickle on a daily basis as weather. If you know better and there are animals with high metabolic rates that are weather-dependent feeders (and in that I mean animals that need certain conditions to feed at all, not those that just vary their diets due to changes in weather), please let me know and I'll consider myself proved wrong.

      SKim-feeding and projectile-feeding are not the same thing - nothing alike, in fact. I can't see 'skim-spearing' working, either: the angles are all wrong. To spear something, you want to strike it directly with full force of your momentum behind it, not at an acute angle to your movement (which is what would happen in skim-spearing). Maybe, hypothetically, 'dip-spearing' would work, where an animal stabs a prey item on the wing (this is, after all, just dip-feeding but without an open mouth), but I could see this being rather tricky. Dip-feeding allows for a little bit more slop in what is already a pretty-difficult job what with all the forward momentum, relatively stationary prey, projection of the head and jaws and all. A dip-spearer would have to be incredibly precise in its strike or go hungry: maybe this is why no dip-feeders have, so far as I'm aware, become volant projectile-feeders. Possibly. Either way, I've not come across any evidence of pterosaurs being projectile feeders like hammerkops, egrets or herons. Their necks just don't appear adapted for it. That said, I could see some pterosaurs taking something more of a shoebill approach to projectile feeding: you know, launching everything - head, neck, torso, kitchen sink - at a prey item with a lot of running, flapping wings and big splash at the end. Maybe.

      I'll send you Veldmeijer's paper. As for Thalassodromus postcrania, I agree entirely with you and disagree at the same time. We just don't know, do we: it's not at all unreasonable to assume that it's likeTupuxuara, but it could, for all we know, be different enough to have serious functional implications. Another case of 'wait and see', I suppose.

    19. wbt9000 60 months ago | reply

      Hello and Congratulations. I'm just getting around to seeing this and am interested in your original works. Do you sell them? Not that I'm a man of means, but they really do strike me.

    20. OptimisticPainter 29 months ago | reply

      Congratulations Mark!

      You can also claim to the first ever paleo illustration of a wall-flower!

      Matt

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