Quadrupedal Launching In Bats And Pterosaurs

I can't recall when I first heard about 'quad-launching' as a serious suggestion for pterosaurs getting airborne, (I was under a rock, palaeontologically-speaking, between '06 and '12) though Mark Witton's excellent 'Pterosaurs - Natural History, Evolution, Anatomy' was the first time I remember anyone going to any effort to depict it pictorially. Indeed, all of his book's pterosaurs are shown mid-launch for their profile images, as if Mark is making a concerted effort to familiarise readers with the concept. Most of the other books on my shelves tend to hedge their bets, offering up a selection of methods, including (but not limited to) dropping from elevated perches, facing into the wind and spreading their wings, and taking a run up whilst flapping.

My biggest problem with quad-launching was that I found it hard to visualise. I've never seen anything get airborne like that. Given that birds are obligate bipeds and their legs are not connected to their wings by a continuous flight surface, they are free to either jump into the air, as with pigeons, or propel the animal along the ground with an energetic run-up, like swans and geese. Many palaeontologists agree that pterosaurs were obligate quadrupeds and that their fore-limbs and hind-limbs were, in life, connected by the wing membrane. Birds are, therefore, a poor analogue for launching pterosaurs, and it is for these, and other anatomical reasons, that palaeontologists believe that pterosaurs' primary launch method probably involved a highly-energetic 'push up'.

A recent post at Pterosaur Heresies again demonstrates its author's frustrations with the problems he sees with the forelimb launch mechanism. The article points out that vampire bats achieve a considerable height from an initial leap before they perform a single flap, and that pterosaurs would be unlikely to achieve such a feat. In a bid to attempt to understand bats taking off from the ground (only a few species can do this) I looked at video footage of a fringed myotis taking off. Adams et al, in their 2012 paper, looked at how bats use their uropatagium to facilitate launch, and made available the following video:

There are four video links in the online paper, showing launches from various angles. In order to get a better idea of what's going on, I rendered the bat as a very-basic stick figure, traced from screenshots of the first online video. The wings' tracings show the stroke, and the head shows the positions of the animal relative to the ground.

Sequence showing a bat (Myotis thysanodes) taking off from the ground, mapped from screen-shots of film footage. This section of the sequence totals around two-and-a-half seconds. (Sequence drawn by author, traced from footage available with Admas, Snode & Shaw 2012.)

In the next image, the seven stages are overlaid in order to get a slightly clearer view - though I think both diagrams are useful when taken in together. The bat accelerates quickly, with its wings in contact with the ground in stage 1-3 (in 1 and 2, they are still flush to the floor). In stage 4 it begins the upstroke, is preparing for its first proper downstroke at 5, and has achieved that downstroke by stage 7. It's already flying and is only a few inches off the ground. My understanding, at least for M. thysanodes, is that when it jumps its inertia carries it a little higher than it would appear when standing with its arms stretched out beneath it, but it's enough to get the first flap in, and by then it's already airborne.

The same bat's take-off sequence, overlaid in order to better show the small area required for a successful launch. Black numbers denote head positions during launch; red numbers denote left wingtip positions. (Sequence drawn by author, traced from footage available with Admas, Snode & Shaw 2012.)

About a year ago I began work on a graphic novel showing the birth, life and death of Nyctosaurus. I may have underestimated how long this would take to put together, so it's still filed under 'ongoing'. But in order to understand quad-launching, I put together a couple of graphics showing an adult Nyctosaurus getting airborne, both of which inspired the bat graphics:

Overlaid launch sequence for a male Nyctosaurus gracilis. (Copyright © 2014 Gareth Monger)

And the looong version:

Launch sequence for Nyctosaurus. Nicked from my deviantART profile, hence the whole lo-res thing. Copyright © 2014 Gareth Monger)

So there you go. Now that I've done the bat thing, I might refine the Nyctosaurus graphics. I might even put together a cel animation at some point. There's nothing overly scientific in all that, however it might prove useful for those of you out there who are into your leather-flappers and pterosaurs.


References:

Adams RA, Snode ER, Shaw JB (2012) Flapping Tail Membrane in Bats Produces Potentially Important Thrust during Horizontal Takeoffs and Very Slow Flight. PLoS ONE 7(2): e32074. doi:10.1371/journal.pone.0032074

Elgin, R.A., Hone, D.W.E., and Frey, E. 2011. The extent of the pterosaur flight membrane. Acta Palaeontologica Polonica 56 (1): 99–111.

A new blog necessitates an introduction

Hi, and thanks for checking in on my blog. I daren't say anything too earth-shattering here, as this is my first post, but I'll say enough so as to introduce myself and let you know my master plan or, as homage to recent Doctor Who developments, 'Mistress Plan'.

I graduated in BA (Hons) Scientific & Natural History Illustration in 2002, having spent a good deal of it drawing, painting and modelling Mesozoic reptiles. It was during this time that I also began illustrating commercially, but I'll save those details for a CV page in the near future. Suffice to say that I've continued to illustrate, occasionally for money, but recent months have seen me change direction slightly. Whilst straightforward one-offs, or occasionally batches for publishers, are great, there simply isn't that much work out there for the would-be full-time palaeoartist and it is for that reason that I'm going the self-publishing route. And this time I'm not jacking in the day job. I've done that before. It didn't end well.

So, I'm writing a book, doing it all myself. I don't have to hunt down that rarest of things: a palaeontology book project without an illustrator. This is actually my second book. The first was a compilation of email correspondence between me and a real-life email scammer. It came about by accident, after I sent a throw-away reply from a redundant email account to one of those dodgy emails from someone in Burkina Faso. Inexplicably, the exchange continued for several weeks and, at the suggestion of a couple of people following the updates on Facebook, I threw it together and uploaded it to a print-on-demand service, here.

It was one of those annoying little distractions, but it was a good learning experience. As far as books go, it won't share shelf space with Dickens, but you might find it next to The Heart Felt Letters. My current project is palaeontologically themed, focusing on those famous cousins of the dinosaurs, the pterosaurs - hence the name of this blog. Now, there are many excellent overview-style books, such as the slightly-dated Wellnhofer's Illustrated Encyclopaedia of Pterosaurs or Mark Witton's must-have Pterosaurs: Natural History, Evolution, Anatomy, and I am keen not to repeat that format. So I can't cover pterosaurs as a whole, but I can pick one and tell its story.

And tell its story I will, literally. And graphically. Imagine a wildlife documentary, set in the Late Cretaceous but storyboarded as per a graphic novel. That's what I'm aiming for. And the star? Nyctosaurus gracilis, which is a smallish pterosaur, closely related to the giant Pteranodon. Like Pteranodon, it possessed a crest, though Nyctosaurus's crest is proportionally much larger; the distance from its beak tip to the top of the crest is approximately equal to the length of one of its wings. It looks weird. Weird and magnificent and perfectly adapted to a life on the wing. Uniquely (as far as we know) it had lost manual digits I, II and III, retaining only the long wing finger, and even this was reduced to three phalanges. Crazy head gear and crazy wings. Surely the perfect candidate for a graphic novel about the life story of a pterosaur?

The book's already well underway, suffering the usual bumps in the road which life likes to throw at worthwhile projects. The next stage is the tough bit: getting on with it.

Nyctosaurus: Life and Death of a Late Cretaceous Pterosaur is scheduled for release some time in 2014, and hopefully before Flugsaurier '15.  It will be published by Ecen Books.