Gravity cannot reach us anymore

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    I'm a big fan of recycling. Any rubbish we have around the house is a candidate. Bottles and jars? In they go. Polystyrene and foam packing? That's in too. Food waste? Compost it. Bottle tops? Well, not really meant to, but I figure if I keep throwing them into recycling waste then someone, somewhere, will eventually get the message that they should be recycled, too.

    In keeping with this spirit, I'm not going to write anything new to go with this image: I'm going to recycle something from elsewhere. All you need to know before diving into this second-hand text is that the image above depicts a Pteranodon taking off, but obviously using its arms, not its legs, as the main launch propulsor. This may seem a bit odd, but read on and all will be clear.

    --

    The first stage of achieving flight, of course, is becoming airborne. As alluded to above, quite how pterosaurs did this has long been a problem and running starts, gravity, headwinds and/or different atmospheric conditions have been pulled in to help. Whilst there is little evidence for the latter, you can just about scrape an argument together that pterosaurs living in coastal or marine environments may have been able to find enough cliffs or wind to regularly employ them in takeoff, but the same certainly cannot be said for the increasing numbers of pterosaurs turning up in inland continental deposits. Inland settings are often very flat, windless and densely vegetated places that really limit the potential for finding suitable pterosaur runways. It’s particularly interesting that the real pterosaur giants, the azhdarchids, are most abundant in terrestrial settings too, as they presumably needed the longest, widest runways, strongest headwinds and sloppiest slopes to takeoff: it’s hard not to wonder just how many places these guys could conceivably take off from under such constraints. Adding further fuel to this quandary is the recent calculations by two teams of authors that suggest pterosaurs massing above 70 kg (Chatterjee and Templin 2004) or even 41 kg (Sato et al. 2010) were unable to launch at all, regardless of environmental assistance. These masses are strikingly low when the arguments on pterosaur mass outlined above are taken into account and, moreover, the widespread distribution, longevity and apparent volancy of all known pterosaurs seems to suggest their flight was not so environmentally limited. In short, then, our problem is thus: how did realistically massed pterosaurs become airborne without the luxury of a Mesozoic airport?

    The answer, it seems, comes from the fact that we’ve been looking at only half of the picture. It has always been assumed that a pterosaurs launching from a flat surface will have taken off in a bird-like fashion, using a leap or a run to attain the velocity needed for flight. While this assumption may appear quite safe and, indeed, the strength of pterosaur hindlimbs have been noted (Bennett 1996; Padian 1985), two American pterosaur workers, Jim Cunningham and Mike Habib, have long pointed out that assumptions of bipedal launch contradict other evidence (e.g. Habib 2008). For one thing, it’s notable that walking and launching are achieved using the same gaits in birds and bats: birds walk and takeoff bipedally, whilst bats do the same tricks as quadrupeds. We may expect, ergo, that pterosaurs may have also stuck to their quadrupedal gait whilst taking off. Similarly, it turns out that launching with the hindlimbs alone seriously pumps up the leg skeleton of the launcher: bird legs scale much faster with mass than other parts of their bodies - even their wings - to meet the demands of shoving their weight into the air with only one set of limbs. Pterosaurs, by contrast, do not have particularly robust legs for their size but do bear strong, overscaled forelimb bones that are particularly well-developed around the shoulders (Habib 2008). Under mechanical analysis, these bones are more than strong enough to catapult twice the weight of a given pterosaur into the air, whereas their hindlimbs would fail at much lower stresses.

    What this all points to, then, is the high probability that pterosaurs took off quadrupedally and, in all likelihood, from a standing start. Firstly, the pterosaur would crouch before shoving up and forwards with its hindlimbs to vault over its own arms. Almost simultaneously, the powerful forelimbs push upwards, changing the trajectory of the pterosaur body from one moving primarily forward to one moving forward and skyward. Whilst this is occurring, the wing finger is being extended out to open the wing and, as the animal becomes entirely clear of the ground, a partial upstroke is achieved as the arms are swept above the shoulders. The wing is fully open by the end of the upstroke and full flap cycles can begin, which the pterosaur would continue as it ascends to a suitable height. All this would take place in a very quick, highly synchronised fashion and even the largest pterosaurs would be clear of the ground in a second or so.

    Such a sight would certainly be worth shedding out some cash to see and it’s worth taking a quick moment to consider the prospect of a giraffe-sized monster azhdarchid launching itself into the air in this way. What’s more, while this may sound like the latest in the long line of crazy ideas that have been proposed about pterosaur habits, bear in mind that a number of bats (most famously vampire bats) launch in a very similar fashion and, because they employ the most powerful muscles in their body –those developed for flight – their takeoff is particularly powerful and efficient (Schutt et al. 1997). In fact, little vampires almost spring into the air vertically, a trick, it must be said, that would not be seen in larger pterosaurs. With greater masses to heft into the air, climbout angles would decrease as size and mass increased, meaning the largest pterosaurs would require a relatively clutter-free area immediately in front of their launch site. Still, it would seem odd for large, gangly, volant animals to hang around in woodlands or forests anyway, so this probably wasn’t much of an issue. The evidence for quadrupedal launching appears pretty convincing, then and, if sceptics need further evidence of this behaviour, there are rumours of a trackway that may show a pterosaur taking off in just such a fashion (Habib, pers. comm.. 2010).

    --

    Pretty neat, huh? If that doesn't stir your palaeontological loins, nothing will. Before we go, though, a word on the source of that text: eagle-eyed readers will have noted references to preceeding text that was not reproduced here and, clearly, there's a list of cited literature associated with the piece, too. Where did it come from, then? Well, folks, you've just read a short excerpt of the first draft of a book that I'm currently writing: yup, after years of people telling me to write a book, I've finally picked up a pen - er, keyboard - and got cracking. It exclusively covers pterosaurs, unsurprisingly, and is intended to be equal interest to researchers and interested layfolk. Princeton University Press will be publishing it next year and, with 100,000 words and 200 illustrations planned, it should be capable of holding open even the weightiest of doors. It's planned to be about A4 size and most pictures are in colour, so it should look reasonably pretty too. While we're all here, actually, anyone comments or suggestions about the style of the text above will be appreciated: too technical? Too patronising? Too verbose? This is, after all, a book aimed at you (yes, specifically you. By the way, you have a little food next to your mouth) so any comments will be welcome.

    Right, best get back to work. The hardest part of the whole thing awaits me: I've still not decided exactly how to start it. A tangential discussion of lamposts, perhaps? Or maybe how cookbooks always list 'chicken mince' as an ingredient and yet I've never seen it anywhere in the shops? I'm sure that's an allegory of something in pterosaur research. Probably.

    sandrino, Tetzauh, Babbletrish, and 17 other people added this photo to their favorites.

    1. sjonsvenson 44 months ago | reply

      One problem with recycling is that if we do it really efficient then palaeontologists and archeologist wil not find anything back ... so remember th throw the odd stuff away.

      ^_~

    2. Mark Witton 44 months ago | reply

      That's true. Maybe we should strategically bury things for future generations every now and then. We could do cryptic things to make it more interesting, too, like removing skulls, throwing joints into impossible postures, placing animals in environments where they have no right being and that sort of thing. Don't want to make life too easy for them, after all.

    3. Andy Morley 44 months ago | reply

      Looking forward to seeing the first book in what will probably become a series!

      Is there any talk of evolution of the take-off as these animals evolved and moved around the different environments? I imagine they didn't just decide one day to take-off in such a way, rather gradually developed something that prolonged falls from cliffs/trees/high places and then developed into the full winged front arm fling described above?

    4. Ralph Stickley 44 months ago | reply

      I am incredibly looking forward to this book! However, I am having a really hard time picturing what a take-off would look like. Some sort of step by step picture would be nice here...did Muybridge ever do Pterosaurs?

    5. Tetzauh 44 months ago | reply

      Really cool. I also have trouble visualizong the whole process, Maybe insets of the various steps, comic-book style?

    6. sjonsvenson 44 months ago | reply

      Or we could mix things up, subtly. Like burrying a dog's sceleton with a cat's head. dumping a clothes washer ... with dishes and table ware in it. ^__^

    7. mikehjt 44 months ago | reply

      Very cool, Mark. With all that is going on with pterosaurs, I'd been hoping someone would do a new book to carry on where Unwin's 'Pterosaurs: From Deep Time' left off.

      On the use of breezy style, if you explain early on that you are doing it to capture some of the excitement and discovery that is pterosaur research but that the rigor is there all the same, I think it will fly. But if you do go with that style (and you do it well), ditch "volancy" and just say 'ability to fly'.

      Really looking forward to the book. Is it done yet? :-)

    8. Mark Witton 44 months ago | reply

      Thanks for the comments and encouragment. To those wanting to visualise the launch procedure in more detail, you can watch this video showing just that thanks to the combined efforts of artist Julia Molnar and biomechanicist Mike Habib, who's work is heavily cited above.

      Andy: long time no speak, see or anything for that matter. We really should meet up at some point: I'm now very flexible with my time, so let me know when you're free. As for the evolution of this launch proceedure, it probably ties in nicely with the evolution of pterosaur flight and, possibly, the terrestrial locomotion of basal pterosaurs and their ancestors. I'll be covering it in my book: for those who know pterosaur literature, it's a reworking of Rupert Wild's 70s and 80s ideas of a hypothetical pterosaur ancestor. I'll say no more for the time being, at least until I get too excited about the idea and blurt it out prematurely.

      Mike: The book certainly will be breezy: I find it hard to write in any other way (it used to really wind up my English teachers at college). I may retain 'volancy' for variation in my vocabulay: my pterosaur flight chapter would otherwise have 'fly' or other similar words in every sentence. Thanks for the suggestion, though!

      "Really looking forward to the book. Is it done yet? :-)"

      As of this morning, I'm 3 per cent done on the text and 2 per cent on the illlustrations. The deadline is next July: should be all right to meet that. Probably.

    9. Babbletrish 44 months ago | reply

      First off, absolutely fantastic artwork, Mark! I saw the head and thought I was looking at an insanely detailed sculpture at first!

      Secondly, all this talk of strategically burying things for future civilizations to find got me thinking about this thing I wrote about time capsules, and what I would place in a time capsule to commemorate the just-ended 2000s decade (with tongue firmly in cheek). The problem, I think, is assuming that the significance of the items will either pass down into history or be immediately apparent, and that the people of the future will understand without question why the items are important and what they mean...

    10. sjonsvenson 44 months ago | reply

      @Babbletrish, I think significance is not as important as we think now.
      Considder the remains we found from people of, say 50.000y ago. Their discarded stone tools and thrown away food remains and bones and clammshells as well as their burial gifts. The discards which they most likely asumed were utterly unimportant and insignificant tell us how they lived and what thier cumunities looke like (more or less). Their valuable and well selected burial gifts tell us they cared for the dead but tel us nothing about how they cared for the living.

      So if you ever make a real time capsule, make sure you drop in a couple of garbage bags among the valuables ^_^

    11. mikehjt 44 months ago | reply

      "To those wanting to visualise the launch procedure in more detail, you can watch this video ...."

      Extremely cool. It does make it clear just what you're talking about. And then the full speed at the end is spectacular.

    12. Babbletrish 44 months ago | reply

      ^ That was kind of my point. I was putting nothing *but* ephemeral trash in the capsule. XD

    13. siamesetigerari 44 months ago | reply

      I like this, it's pretty cool. Looking forward to your book! The prose tone is just right, detailed enough without walloping me with so much detail I need to start checking the dictionary, looking for a glossary or take a class. Excellent argument for quadrupedal launch, it makes sense to me.

    14. Marco Tedesco 44 months ago | reply

      Another pterosaur book!!Another beautiful Mark-Wittonian artwork!! Go straight on the Stairway to the pterosaurological Heaven, Dr.Witton!

    15. adamspong 42 months ago | reply

      Mark, this quadrupedal launch theory is compelling, especially given the example of the bat. But I don't understand why a standing start would be implicated by this view. Could you elaborate on that perhaps? Standing would be fine for the smaller guys, but wouldn't the larger pterosaurs still need to build up substantial speed? Wouldn't a *quadrupedal* running start be consistent with this launching mechanism? You suggest that the larger ones would need open space in front of their launch site, but do you also imply that they'd need a head start? I would be interested to know how much we can determine about the speed required here.
      By the way, I would be very excited to see a book on pterosaurs with your excellent artwork.

    16. b1b5addaf6068a2151d478e3fb26f28b 40 months ago | reply

      I see that this excellent question was posted a couple of months ago, but I might as well post an answer for others to read should they stumble by. There are three reasons why a standing start is proposed for large pterosaurs, as implicated by the quadrupedal launch scenario:

      1) Running launch does not actually correlate with size in living animals. The only running launchers today are members of Aves (birds), and most of the running launchers are semi-aquatic, suggesting that running launch is related to compliant surface takeoff, not body size. Some large birds run a long distance to launch (albatrosses), while others of equal size take only very short runs (bustards), and still others don't run at all (wild turkeys, the males of which clock in as one of the largest flying birds alive - bigger than an albatross by a good margin).

      2) A pterosaur launching quadrupedally would not gain any advantage from running, as it would need to stop the run, enter a crouch to preload, and then leap to maximize launch efficiency. The run does not add anything.

      3) Running is not required - power analysis suggests a standing launch time of 0.45-0.60 seconds for Quetzalcoatlus northropi. If they could launch from a standstill then there is no reason to add extra steps. While running would not add anything, a series of bounding motions could allow a build up of speed over distance - but again, there's no need for those from the ground, so it's unlikely (water, however, changes the rules a bit...)

      Cheers,

      --Mike Habib

    17. adamspong 39 months ago | reply

      Interesting, thank you. The contrast of a standing turkey with an albatross is instructive.
      Next question (the most important one): could the largest pterosaurs fly effectively with the weight of, say, an adult human on their back????

    18. threefingeredlord 39 months ago | reply

      Being without a camera at the moment, your paleo-art/writing is the only reason I have to be logged on to Flickr :).

      Whenever I see your art in newspapers/magazines, I always rip it out and save it, so I'll certainly be purchasing your book when it's out!

      Adamspong's question will continue to haunt me until I find the answer lol, will it be in the book?

    19. Mark Witton 39 months ago | reply

      adamsprong: Mike Habib tells me there's enough strength in azhdarchid limbs to launch twice it's normal weight into the air. So, assuming you're not some kind of human heffer, you could strap a saddle to it (though fitting it would be difficult: how do you negotiate the wing membranes with the saddle straps?) and ride that puppy to work/school/the movies. Thinking about it, if you decked it out with some bangles, jewelery and LEDs you'd look the business wherever you turned up. MTV should do a new show: 'Pimp my Azhdarchid'.

      threefingeredlord: That's very nice of you to say: I'm hoping to put some more of my book online soon, so watch this space.

    20. jada1-txt me-619-456-3164 [deleted] 9 months ago | reply

      cuteee picc ^.^ .

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