Water Launching Pterosaurs

This post is a cross-post from H2VP (again), but should be of interest to pterosaur.net readers.

I gave two presentations at SVP this year, and the second (in the form of a poster) was on pterosaur water launch. Specifically, I presented a model that Jim Cunningham and I have worked out for a plausible water launch strategy in Anhanguera. If you want to see what this might have looked like, turn your cursors here to Mark Witton's website. The relevant illustration is on the far right.

I will not give too much detail on this presentation at the moment, as it is shortly bound for PLoS ONE. However, here are some of the highlights:

- A bipedal water launch model appears to fail for Anhanguera (and other pterosaurs), just as the bipedal model fails for their terrestrial launch.

- A quadrupedal water launch model, in which the wings are the primary mechanism used to free the animal from the surface and to push along the surface to reach launch velocity, seems to check out for all of the parameters we can currently estimate with any confidence.

- Anhanguerids probably took multiple hops across the water surface to launch, but our calculations suggest that most of the actual energy expenditure was spent escaping the surface tension.

- Our model makes testable predictions about comparative anatomy of pterosaurs, which is important when building these kinds of models from fluid theory. Our model predicts that water launching pterosaurs should have features such as: warped deltopectoral crests or dp crests with flared distal ends, enlarged scapulae, extreme disparity between forelimb and hindlimb lengths, and reinforced scapulo-notarial joints. We have a more extensive list of features that can be shared a later date, but the primary note here is that these predicted features do indeed seem to show up mostly in marine pterosaurs, and less so in terrestrial taxa, so there is a least a loose, pattern-matching form of validation that can be applied to our hypothesis.

We hope to have animations and a full paper out on the topic of pterosaur water launch in the near future (next few months) so stay tuned!

Aurorazhdarcho - a Jurassic azhdarchoid

Just a short post on this little fellow. I don't generally like blogging on new taxa as a lot of other people cover them and there's generally not much that can be said from an outside perspective that's not in the paper. I don't have much to add in that respect here either, but this is a nice thing for me to see out as I've seen the specimen knocking around in Dino Frey's office on a number of occasions over the last few years while being assured it would be described 'soon'. Well, now it is out and Aurorazhdarcho is born.

The specimen is obviously in superb condition (photos above and below lifted from Frey et al., 2011) though the head and neck are gone. Still, an impression remains on the sediment to show where they originally lay and given an idea of their original size and shape which is rather nice.

The most interesting thing though is the identification of this as member of the azhdarchoids. This most derived of pterosaur clades are otherwise known only from the Cretaceous, though a Jurassic origin is to be expected if (and for some, this is a big if) you accept that Germanodactylus is a dsungariptid and that this clade is the sister-taxon to the azhdarchoids. Certainly it has a few features that are unique to the group (that huge hindlimb for starters) and this identification looks good to me (though I have to confess I have yet to read the paper in full detail), though as ever with a specimen like this, the lack of a head is a real shame.



Frey, E., Meyer, C.A. & Tischlinger, H. 2011. The oldest azhdarchoid pterosaur from the Late Jurassic Solnhofen Limestone (Early Tithonian) of Southern Germany. Swiss Journal of Geosciences in press.

Dinosaur Revolution: Anhanguera

This is actually a cross-post from H2VP, but it seems quite relevant here, as well. Those of you that watched episodes 3 and 4 of Dinosaur Revolution (which aired exactly one week ago) saw the sequence focusing on the large pterodactyloid pterosaur, Anhanguera. This was one of the sequences I had the most input on, so I thought it might be fun to chat briefly about some scientific background that inspired the sequence.

Parental care in pterosaurs?

The sequence opens with a mother Anhanguera visiting her nest of offspring, whom she then kicks out of the test for their first flights (these end poorly for the first two babies, but the "hero" character survives to fly another day). We have relatively little evidence regarding the specifics of parental care in pterosaurs. What we do have is good evidence that pterosaur babies were able to fly very early in life, and that the eggs were of a soft-shelled structure, which implies that the eggs were buried in foliage rather than brooded in the manner of birds. This manner of egg-laying alone does not tell us much about parental care - "leathery" eggs are laid by some taxa that do guard young (crocodilians) and many that do not (most squamates, though some of those guard nests and young, too). However, the fact that baby pterosaurs were so well developed, and likely able to fly early in life, is at least suggestive that there was not an extended period of parental care. Baby pterosaurs probably set off from the nest relatively early (possibly immediately). Check out Darren Naish's blog post from February on pterosaur babies and eggs for more.

Pterosaur Locomotion

There are three major types of motion shown in the sequence: ground locomotion, launching, and flight. As it turns out, the first two of these are really the same "mode" of movement. After speaking with David Krentz, he and I thought it would be interesting to show the baby Anhanguera hopping in a saltatorial fashion. There are no trackways that show this mode of locomotion in pterosaurs, but we also don't have any trackways that can reliably be mapped to ornithocheirids yet, and the limb proportions of ornithocheirds like Anhanguera are consistent with a saltatorial method of movement. This observation is noted in the paper that Mark Witton and I published in 2010. It is published in the highly acclaimed, open access journal PLoS ONE, and is freely available here.

The takeoff mechanism features the quadrupedal launch model that I proposed in 2008, and which was further used to make predictions about pterosaur ecology by Mark and I in the PLoS ONE paper. Julia Molnar generated a wonderful animation of quadrupedal launch for Anhanguera, and it has appeared across multiple venues, including National Geographic. She was subsequently kind enough to make it freely available on YouTube. I have inserted the video below. You can also pull it up by clicking here.

I have written about quadrupedal launch on other web resources previously, so I won't belabor the point here. In short, takeoff acceleration in animals tends to be generated mostly by the walking limbs, rather than the wings. As such, takeoff is really a form of running or leaping (usually the latter). The strengths of the limb bones in bending and torsion, particularly with regards to the moments sustained for leaping, are therefore highly indicative of launch mode. Pterosaurs turn out to be much more bat-like in this regard than bird-like: they had forelimbs which were much stronger than the hind limbs across a wide range of body sizes. By contrast, large birds have stronger hind limb elements (particularly the femur) when compared with the forelimb elements. Giant pterosaurs, such as Quetzalcoatlus, had very long, thin hind limb elements, which argues against a bird-like launch. However, because pterosaurs walked on their folded wings, as well, the incredibly robust forelimb musculature and structure could provide most of the launch power (and sustain the resulting forces) during a quadrupedal launch. Since pterosaurs were quadrupedal while moving on the ground to begin with, this is actually the most simple model, as well. Modern bats, particularly vampire bats and New Zealand short-tailed bats, use a quadrupedal launch.

There are a host of other problems with a bipedal launch in pterosaurs, including problems with angle of attack of the wing, trailing edge flutter, Wagner effects, insufficient height and time, and pitching instabilities. Depending on interest, I may do a summary of these observations at a later date.

There is not much to say specifically about the flight patterns. One nice thing was that the flapping amplitudes used were pretty reasonable. The wing cycles are probably a bit too large in some cases (particularly the Quetzalcoatlus models that do flybys), but it's usually much worse. The problem here is that large animals actually tend to fly with more shallow wing strokes, especially if they have high aspect ratio wings. This tends to make a distant albatross etc. seem a bit smaller to us than it really is, and the same happens when doing pterosaur models - they just don't look as huge if you model them correctly. In Clash of the Dinosaurs, I tried very hard to get the animators to reduce the flapping amplitude of the Quetzalcoatlus model to no avail - there was a general feeling from those working on the show that the giant size didn't come across with the lower-amplitude wingbeats that are predicted by anatomy and fluid mechanics. Oh well, such is life.

H2VP

On the note of shameless plugs, readers of pterosaur.net may be interested to know that Justin Hall and I have launched a paleo blog called H2VP that will focus primarily on functional morphology and biomechanics of fossil vertebrates. We will be discussing pterosaurs from time-to-time (though I will be posting the dedicated pterosaur work here), as well as other Mesozoic animals that pterosaur enthusiasts may have interest in (right now theropods are featuring strongly, and an article on Mosasaurs will be forthcoming soon).

The blog can be found at: http://h2vp.blogspot.com/

Crazyass pterosaurs and massive, shameless self-promotion

It's been a good while since I've posted anything here at Pterosaur.Net, and with good reason: a fair number of little projects, writing a book, moving house and the continued search for employment have kept me pretty busy for the last few months. One little project that I thought would be of interest to Pterosaur.Net readers, however, is my own website, the ego-trip/interactive CV/desperate bid for work that is Markwitton.com.

I've never designed a website before, resulting in a pretty simple design but, happily, I reckon it's fairly easy to read and navigate. I'll wager that Pterosaur.Net readers will find the full details of my upcoming Princeton University Press book, simply called (for the time being, anyway), Pterosaurs of most interest: you can find a full contents listing, sample imagery and an entire sample chapter, that dedicated to the recently-discovered weirdo pterosaurs from China, the boreopterids. Long term denizens of this blog may remember that Dave Hone mentioned Zhenyuanopterus, a recently discovered boreopterid, on these pages in March of 2010, and you can see a couple of the same critters lazily decorating the top of this post. They're crazy looking animals, bearing tiny, piggy-little eyes and buttloads of needle-like teeth that look useless for anything but straining pasta. But what sort of pterosaurs are they? How many boreopterids are there? Where and how did they live? Point your browser here to find out. (Snazzy Markwitton.com logo shown below)


Other pages of note include new illustrations, technical drawings and details of the 2010 London Royal Society/University of Portsmouth pterosaur exhibition and other sculptures. Oh, and a full list of my technical publications, including links and downloadable pdfs, can be found here. Please take a look and, by all means, drop me a line if you have any comments (especially if you have any functionality issues: I'm sure there's some kinks to work out. The same goes for typos I may have missed, for that matter).

No promises to post anything here anytime soon, I'm afraid: I'm moving house in the coming weeks and am quite desperate to get this book of mine finished, so I simply won't have the time. I genuinely don't know how regular bloggers manage to keep up their output: they must never sleep. Or eat. Or get distracted for long periods in the shower by their toes. In any case, I hope to get back to regular posting at some point in the future, but can't quite say when. Until then, thanks in advance for taking a peep at my site, and I hope you enjoy what you find.

Interview with John Sibbick

Over on my main blog I have an interview with palaeoartist John Sibbick. This is rather relevant to P.net as John was the artist for the very important pterosaur encyclopedia of Peter Wellnhofer back in 1991. John was good enough to share a bunch of his artwork, including some of his originals for this book and a rather nice Dimorphodon skeleton. So click on the link and go and enjoy.

A Pterosaur Revolution?

Back on my Archosaur Musings, I've been talking about dinosaur discovery rates for the last day or two and it seemed worth musing for a few lines on the same phenomenon with regards to pterosaurs. New pterosaurs are being discovered at only about a quarter of the rate of new dinosaurs, though given that there are far fewer pterosaur researchers than there are for dinosaurs, and the overall greater rarity of pterosaurs, this in fact probably represents an overall relatively higher rate of pterosaur discovery even if the absolute numbers are lower. That is already quite significant to my pterosaur-centric mind and belies the pterosaur revolution we seem to be undergoing.

On a slightly cloudier note, the ongoing controversy and problematic taxonomy of a number of groups or genera does mean that it's likely that a number of these new taxa will be sunk back into obscurity. While obviously this is the fate of some taxa in all groups, to my eye the pterosaurs to tend to do a bit worse in this area that do say the dinosaurs. Still, when just a few years ago Dave Unwin surmised there were only around 110 valid pterosaur genera after nearly 200 years of research, the fact that we have been able to add around 20 more in the last three years alone is stunning. Next year might well provide a bumper harvest too with the next Flugsaurier volume due.

While they're never going to get the same attention as dinosaurs, the last decade for pterosaur research really does point to a quiet revolution. We have more active researchers now than ever before (and by a fair margin) and we seem to be drawing in more attention from other workers (that is, there are quite a few dinosaur and archosaur guys who dabble with pterosaurs when in the past they wouldn't have done so) and we're getting together regularly too and producing whole volumes of papers. We're seeing not just a huge increase in the numbers of new genera, but even entire new clades like the boreopterids and chaoyangopterids, unexpected late surviving toothed taxa, and of course Darwinopterus makes quite a difference. There are also major increases in our knowledge of older taxa - there are lots more anuroganthids and azhdarchids than a few years back, and other discoveries are adding massively to our knowledge. You'd struggle to find even a handful of really good specimens with soft tissues a decade ago but now we are positively blessed, and we now have 4 pterosaur eggs (and three of them with embryos) when before 2004 we had none.

At the risk of a little hyperbole, I really think we are in the midst of something special happening with pterosaurs and I genuinely think that in a few decades we will look back at the time between around 2000 and 2020 as the time when we really got to grips with these taxa and much of our knowledge settled into a familiar pattern. There will of course be more surprises and changes to our ideas, but this is very probably the beginning of a new age of pterosaur science and their renaissance (which dinosaurs had in the 80s and 90s) is begun.