A bit more about the AMNH Exhibit

Many thanks to Dave Hone for posting the great photos from Steve Cohen of the new AMNH Exhibit. I have been meaning to post about the exhibit over a month now, but April-May is the skeletomuscular course in the medical program at USC, so blogging has been on the back burner.

In any case, as Dave mentioned, I had a role in the new exhibit. In fact, I had a relatively substantial role. As full disclosure, I was a paid consultant on the exhibit (titled "Pterosaurs: Flight in the Age of Dinosaurs"). I worked with the staff there for a little over a year on the interactive flight simulations, and I did recorded interviews for use in the theater and iPad interactive displays. I also helped rather extensively with the script used for the theater presentation (which is mostly about flight). One thing that neither myself, nor Alex Kellner (the co-curator on the exhibit) were approached about were the promo images. I won't detail any politics on that front now, but some of you may be aware that there some issues that arose on that front. What I can say is that the animation and video folks were not involved in that process, either (and used entirely different models for their reconstructions), nor were the sculptors so far as I am aware. So the promo images seem to be a bit of an isolated entity.

In any case, the exhibit opened on April 5th, 2014. Here is the official website for the exhibit: http://www.amnh.org/exhibitions/current-exhibitions/pterosaurs-flight-in-the-age-of-dinosaurs

They ran a promo video here: https://www.youtube.com/watch?v=AsI8ZtsSVqY

On April 1st there was a media preview event, with a panel composed of myself, Alex Kellner, Mark Norell and Michael Novacek. It was well attended, and yield quite a bit of press for the exhibit. Some of the popular articles can be found at:

http://news.nationalgeographic.com/news/2014/04/140405-pterosaur-flying-reptile-museum-exhibit-paleontology-science/

http://www.nytimes.com/2014/04/11/arts/design/natural-history-museum-explores-the-wonders-of-pterosaurs.html

http://worldsciencefestival.com/blog/pterosaurs_take_to_the_skies_of_new_york_city

http://mentalfloss.com/article/56005/qa-michael-habib-pterosaur-flight-expert

http://www.livescience.com/44556-how-pterosaurs-ruled-the-skies.html

http://mentalfloss.com/article/56021/10-pterosaur-facts-new-exhibit-american-museum-natural-history

As always, there is some variation in the quality of coverage, but overall I thought the writers did a good job of talking up the exhibit while hitting some of the interesting science involved. There will likely be more coming from Scientific American, as well, since I have chatted with them pretty extensively in the weeks following the opening (but more on that when the article(s) hit print).

Some things to look forward to in the exhibit (which stays at the AMNH through early January, at which point it will travel to other museums):

- Excellent specimens. Dave covered this already (see previous post) so I won't belabor it here. They have some awesome stuff, though (including the Dark Wing, which is on display outside Europe for the first time).

- Motion capture interactive animations that allow you to control launch, feeding, and flight in Pteranodon and Jeholopterus. The floating position of the Pteranodon was originally quite bird-like. It was updated using the floating paper by Hone and Henderson at my suggestion. The Pteranodon launch is a water launch and looks pretty wicked. The flight simulation includes basic physics like stall, L:D ratio transitions, and basic rate of climb estimates.

- A full-scale fleshed out reconstruction of Quetzalcoatlus northropi hanging from the ceiling just above reach, with a cutaway to show plausible flight muscle attachment. It's a great sculpture. Sadly, it came together just a little too soon to incorporate the updated proportions from my project with David Krentz. They did, however, feature David's 3D digital model on a sign near the sculpture showing how our reconstructions of Quetzalcoatlus have evolved over time.

- An amazing sculpture diorama (full size) of Tupuxuara - the models are by Jason Brougham, who is fantastic at paleo-reconstruction. The pair is shown feeding on fish in a traditional pluck-grab mode. As some know, Mark Witton and I both prefer an alternative ecology for these animals, but the sculptures are still magnificent (and to be fair, their feeding ecology is contentious - they can't just side with me every time). 

If you are in NYC, the exhibit is well worth a visit (the specimens alone make it worthwhile).

Cheers,

--MBH

The Beauty of Big

One rather obvious trait of pterosaurs, compared to other flying animals, is that they had a tendency to get rather large.  There has been much to do about how they could get so large (as most readers of this blog know, I and quite a few others now prefer the explanation that pterosaurs were quadrupedal launchers).  However, it's a bit trickier to tackle the problem of why some of them became so large. 

What might select for giant size in pterosaurs?  It's probably not something that can be answered definitively, but there are some plausible options.  One of them relates to the issue of long-range travel.  I talked a bit about this potential advantage here. The gist is this: being large makes long-distance travel more feasible for most animals, particularly flyers.  Some reasons this happens include:

1) Large flyers can carry more fuel.

2) Large flyers travel at higher speeds, on average.

3) Large flyers are less affected by adverse weather conditions.

4) Large flyers use less fuel per unit body mass, per unit time.

This means that, on average, a big flying animal can go longer between stops on long migrations, and gets to their destination more quickly, than a small flyer.  This might be particularly important for a flyer which feeds on resources that are patchy in their distribution.  This, in turn, might suggest (very tentatively) that animals like azhdarchids had a tendency to travel long distances between food sources.

Of course, there are a host of other advantages to being large, as well: big animals are harder for predators to kill, can eat larger prey, and can (in some cases) better defend young.  For egg-laying animals, large size often improves fecundity.  So there is no way to say for certain exactly why some pterosaurs grew quite large, but it does raise questions of general biological interest.

It’s dumb, it’s awesome, it’s… Our lives with pterosaurs, part 2

If you’re wondering what’s going on here, or if you’re looking at the right blog, it’s probably because you haven’t read this yet. And yes, we are stooping this low.

 

Pterosaurs in the modern day! What would it be like if some pterosaurs survived the K/T extinction to coexist amongst our modern biota and in modern environments? Such are the questions we're attempting to answer here. Just to remind you, the only pterosaurs under direct scrutiny in these posts are azhdarchids and nyctosaurids as they seem to be the only pterosaur lineages that were present at the terminal Cretaceous. We spent a lot of the last post discussing how we may try to exploit pterosaurs for our own benefit, and in this concluding post we’re going to consider how we may succeed at coexisting with wild pterosaur populations. (Adjacent image: when stork-like animals go wrong)

NOTE: The Blogger upload system has been a real pig this evening, and formatting this post has been nothing short of a nightmare. Apologies in advance for any choppy bits of text or other issues. I have tried to correct errors as I go, but please let me know if I've missed any. 

Meeting the neighbours

Humanity would probably bump into wild pterosaurs fairly often. Azhdarchid pterosaurs, in particular, achieved very wide distributions in the Cretaceous, being absent only from Antarctica (Witton and Naish 2008; Ösi et al. 2011; see map, above, for the distribution of azhdarchid fossils. From my Ph.D. thesis). Azhdarchid fossils show very strong ties to terrestrial environments,either being preserved in continental freshwater deposits and, when they do occur in marine sediments, they tend to be components of mixed terrestrial/marine biotas (adjacent graph is a sexier version of the same data presented in Witton and Naish [2008] on this topic. I’ve not updated it with new data since then, but the statistics will not have changed significantly to my knowledge). Their distribution across the globe suggests they were versatile animals capable of living in different habitats and climates, and their palaeoenvironmental signature hints that they would preferentially frequent terrestrial settings. Modern azhdarchids, then, may be fairly familiar sights to us if they were around today.

We may even find that some single azhdarchid species were found all over the globe. Some of the recent findings on their flight ability are rather arresting, with the 10 m span giants seemingly capable of flight speeds exceeding 100 kph (62 mph; Witton and Habib 2010). Mike Habib's recent SVP talk suggests that they could remain aloft long enough to travel almost halfway round the world in one sitting (Habib 2010) and, to paraphrase him directly, (imagine this being said VERY LOUDLY for full effect. Those who know Mike will understand why), geographic boundaries would mean nothing to these guys. This may mean that the sort of provincialism we see in some modern fliers may not apply to these forms and, indeed, cautionary words on the implications of this have been said with regard to azhdarchid systematics.

We may not find ourselves quite so acquainted with nyctosaurids, however. Their fossils are generally rarer than those of azhdarchids and, to my knowledge, largely constrained the Americas. Their rarity is of particular interest because Nyctosaurus, perhaps the best known of all nyctosaurids, occurs in the Smoky Hill Formation of Kansas, a deposit that has also supplied over 1000 Pteranodon specimens since 1872. I’m not sure how many Nyctosaurus specimens there are around the world, but I get the impression that it may be dozens, not hundreds or thousands (please let me know otherwise if I’m wrong, though). Assuming that this does not reflect other sampling or preservational biases, it seems that nyctosaurids were simply rather rare animals. Their remains, unlike those of azhdarchids, are also found exclusively in deep marine deposits, suggesting they spent much of their time away from land. Nyctosaurid anatomy agrees with their lack of landlubber status: the loss of the three, small manual digits used in walking and embarrassingly small legs do not suggest proficient terrestrial abilities. By contrast, the development of ossified tendons in the forearms of some nyctosaurid specimens (Bennett 2003; Frey et al. 2006) suggests that they put tremendous, continuous strain on their wings, and the wings themselves are super-long and probably very glide-efficient. The impression one gets, then, is of highly volant creatures that probably spent almost their entire lives in the skies over seas and oceans, so perhaps only sailors and fishermen would regularly see them if they were alive today.

Garbage monsters

In developed countries where little or no primary habitats remains, our modern azhdarchids may spend much of their times in rural areas, as this is probably the closest approximation of their natural habitat, and would, perhaps, provide the largest amount of live prey. The feeding habits of azhdarchids have been controversial since they were identified in the 1970s, but, in what is probably the only thorough exploration of their feeding habits to date, Darren Naish and I concluded that they were most likely ‘terrestrial stalkers’, long-legged predators of relatively small animals sought out in sparsely vegetated settings (Witton and Naish 2008). This idea may not be unfamiliar to many of you: not only have Darren and I waxed lyrical about it repeatedly in various blogs and lectures, but it’s now been immortalised on on TV and even in excellent, excellent comic book format (you can also download the full paper for free). Accordingly, I won’t go into details here, but, for the uninitiated, the seemingly proficient terrestrial abilities and long jaws and neck of azhdarchids seem well suited for hunting small game on land and, often, poorly adapted for anything else. The bulk of modern azhdarchid diets may not be too dissimilar to their Mesozoic ancestors, as these ancient forms were likely to primarily dine on small reptiles, amphibians and mammals that would appear, superficially at least, not too different from their modern representatives. Of course, modern azhdarchid diets would lack a certain non-avian dinosaur flavour, and that would presumably be substituted by various mammal species.

Azhdarchid jaws are generalised enough that we cannot rule out some ocassional bouts of scavenging, and it would be silly to ignore the importance of carrion feeding to some modern azhdarchid analogous, the ‘giant’ storks. Some of these birds – particularly the larger Leptoptilos species (e.g. the adjutant and marabou storks) – frequently forage on carrion (Kahl 1987) and, because we humans are disgusting slobs who do not dispose of our garbage properly, they have expanded their taste for lousy food to leftovers on rubbish tips. Other, more familiar birds are also keen rubbish raiders: I’m sure we’ve all seen local crows and gulls riffling through bins or splitting open refuse sacs. I see no reason why azhdarchids would not develop the same behaviours, so we may find some of them colonising urban areas and living off our waste. Perhaps this would mean that some modern azhdarchid species would be fairly resistant to the current global species decline, as the route to evolutionary success nowadays seems to mostly revolve around living off our garbage (well, it is the only resource we’re not running out of). (Image, above, shows said exploitation of waste in action)

If wild azhdarchids did take foot in urban settings, encounters with them may be a little daunting for human residents. As we discussed in the last post, pterosaurs seem to have increased their average body size over time, so later forms were much larger than the earlier. Perhaps we’d feel fairly confident stopping smaller (2.5 m span) animals from spreading rubbish all over our driveways, but would we feel the same about 4, 7 or 10 m span animals? Perhaps not. Plus, did I mention that these pterosaurs may have been gregarious? Several azhdarchid localities have yielded associated azhdarchid skeletons (Lawson 1975; Cai and Wei 1994) or very abundant azhdarchid remains (Nessov 1984; Ösi et al. 2005), suggesting that they were at least tolerant of each other, or perhaps even hanging around in little groups. All told, in this hypothetical world of pterosaurs, we’d probably need to seriously rethink our philosophy on garbage disposal. Probably best to keep the cat in, too.

They can eat my trash, so long as they don’t eat me

Speaking of modern pterosaur diets, an enormous elephant in the room needs to be acknowledged: would we be on the menu? This is a legitimate question, and not because we’re used to Tinseltown pterosaurs having a taste for human meat. Some azhdarchids were so enormous that they could consume people-sized prey (by which, I mean small adults, not just children). We don’t have particularly extensive fossils of giant azhdarchids to test this with, but we do have a key component for answering this question: a giant pterosaur skull fragment comprising the jaw joint and some bones from the roof of the mouth (shown on the left, in ventral view, in the image below). This belongs to the 10 m span Hatzegopteryx, one of the largest azhdarchids known, and is notable for its unusually robust construction of stout bony struts and enormous jaw condyles. By doubling its width we can attain minimum estimate of the complete jaw width, revealing a staggering maw 500 mm across (Buffetaut et al. 2002, 2003). (Image, below, shows the mirrored Hatzegopteryx jaw skull element. The ventral braincase and posterior jaw region of Thalassodromeus is shown for comparison and to scale. Thalassodromeus, by the way, has a jaw of 160 mm width and 700 - 800 mm long. Hatzegopteryx was mucking huge).

We should remind ourselves at this point that we’re a) talking about the minimum width here, so there's possibly room for a little more expansion; and b) these are, so far as we can tell, animals capable of flight, and yet had skull widths that many large dinosaurs would be jealous of. As with many pterosaurs, the asymmetrical nature of the jaw condyle would deflect the lower jaw laterally when opened so that much of the 500 mm jaw width could be used for swallowing food. The posterior palatal region is also highly vaulted, so there is additional swallowing space in the dorsal region oral cavity, too. Combine this with the likelihood of a large gulf between the mandibular rami occupied by distensible gular pouch (known from several exceptionally-preserved pterosaur specimens), and it seems more than likely that Hatzegopteryx could fit a person into its throat.

After that, of course, you’d need to be moved down the long neck, a length up to 3 m if we assume that the giants had necks of comparable proportions to those of smaller azhdarchids. Unfortunately for us, we have good evidence that pterosaur throat tissues were highly elastic and capable of encompassing large prey, so we may slip through an azhdarchid oesophagus without issue. The preservation of a recently-devoured fish in a complete juvenile Rhamphorhynchus specimen reveals just how large some pterosaur prey items were, and how stretchy their throats must have been to accommodate it (see detail of the trunk region of this specimen, below. After Wellnhofer 1975). The specimen in question was preserved in the process of digesting a fish that – as preserved – occupies 60 per cent of its trunk length, but may have been even larger as the anterior end had already been partially digested (Wellnhofer 1975). Pterosaurs, then, may have had small bodies, but they weren't afraid of packing their meals in. Our previous discussions on how giant pterosaurs could support our weight in flight have obvious connotations here, too: if one could support our weight externally, there seems little reason to suggest they couldn’t internally. We may fill their bellies, but we wouldn't impede their locomotion in doing so.

The outlook isn’t looking promising for us, then. Larger members of the populace may be a bit too massive to comfortably digest, but leaner or smaller folks may well be at risk. In any case, giant azhdarchids would be best avoided. If we did encounter one, would our chances of being eaten be high? Perhaps it would depend on context of engagement. On open ground, the 2.5 m long limbs and powerful muscles of giant azhdarchids would almost certainly chase us down and, hey, let’s not forget: they can fly. It's hard to outrun an animal that can fly fast enough to get a speeding ticket on most roads. We may be safe if we could get to cover or a cluttered setting, as the giant azhdarchid bauplan is hardly suited to moving through narrow confines or probing crevices. Without that, though, I don’t fancy our chances. Azhdarchids of this sort may be quite difficult to deal with too, short of simply killing them. Troublesome bears or cats can be moved far enough away from populous areas that they won’t bother people again, but we’d be hard pressed to stop relocated azhdarchids from simply flying back to wherever we caught them. The more I think about it, the more it seems that large azhdarchids would actually be quite a dilemma for us, and one that would probably see most of them being shot. All told, maybe it’s best for us all that they're extinct.

On that bombshell, then, I think that’s enough of this craziness for the time being. Hopefully, someone, somewhere, will have taken something useful from these posts and, if nothing else, we finally have a picture of a cowboy quad-launching a giant pterosaur. With that, I think my work here, and perhaps the respectable portion of my career, is finished. 

References

• Bennett, S. C. 2003b.  New crested specimens of the Late Cretaceous pterosaur Nyctosaurus. Palaeontologische Zeitschrift, 77, 61-75.
• Buffetaut, E., Grigorescu, D. and Csiki, Z. 2002. A new giant pterosaur with a robust skull from the latest Cretaceous of Romania. Naturwissenschaften, 89, 180-184.
• Buffetaut, E., Grigorescu, D. and Csiki, Z. 2003. Giant azhdarchid pterosaurs from the terminal Cretaceous of Transylvania (western Romania). In: Buffetaut, E. and Mazin, J. M. (eds.) Evolution and Palaeobiology of Pterosaurs, Geological Society Special Publication, 217, 91-104.
• Cai, Z. and Wei, F. 1994. Zhejiangopterus linhaiensis (Pterosauria) from the Upper Cretaceous of Linhai, Zhejiang, China. Vertebrata PalAsiatica, 32, 181-194.
• Frey, E., Buchy, M. C., Stinnesbeck, W., González, A. G. and Stefano, A. 2006. Muzquizopteryx coahuilensis, n.g., n. sp., a nyctosaurid pterosaur with soft tissue preservation from the Coniacian (Late Cretaceous) of northeast Mexico (Coahuila). Oryctos, 6, 19-40.
• Habib, M. B. 2010. 10,000 miles: maximum range and soaring efficiency of azhdarchid pterosaurs. Journal of Paleontology, 30, 99A-100A.
• Kahl, M. P. 1987. An overview of the storks of the world. Colonial Waterbirds, 10, 131-134.
• Lawson, D. A. 1975. Pterosaur from the Latest Cretaceous of West Texas: discovery of the largest flying creature. Science, 185, 947-948.
• Nessov, L. A. 1984. Pterosaurs and birds of the Late Cretaceous of Central Asia. Paläontologische Zeitschrift, 1, 47-57.
• Ősi, A., Weishampel, D. B. and Jianu, C. M. 2005. First evidence of azhdarchid pterosaurs from the Late Cretaceous of Hungary. Acta Palaeontologica Polonica, 50, 777-787.
• Ősi, A.,Buffetaut, E. and Prondvai, E. 2011. New pterosaurian remains from the Late Cretaceous (Santonian) of Hungary (Iharkút, Csehbánya Formation). Cretaceous Research, 32, 4556-463.
• Wellnhofer, P. 1975. Die Rhamphorhynchoidea (Pterosauria) der Oberjura-Plattenkalke Süddeutschlands. Palaeontographica A, 148, 1-33, 132-186, 149, 1-30.
• Witton, M. P. and Habib, M. B. 2010. On the size and flight diversity of giant pterosaurs, the use of birds as pterosaur analogues and comments on pterosaur flightlessness. PLoS ONE. 5, e13982.
• Witton, M. P. and Naish, D. 2008. A reappraisal of azhdarchid pterosaur functional morphology and paleoecology. PLoS ONE, 3, e2271.

Our lives with pterosaurs, part 1

Not many mornings ago the lovely Georgia Maclean-Henry and I were discussing the the topic of 21^st century pterosaurs. Not, you understand, as a discussion of whether the reports of late-surviving, cryptid pterosaurs are genuine (they almost certainly aren’t, for reasons discussed in Darren Naish’s assassination of this idea), but a hypothetical premise that pterosaurs were commonplace components of our modern fauna, and what they would be like to live with. Though obviously speculative and completely juvenile, I thought this may be fun to blog on and discuss with others, so feel free to chime in at the end of the post with your own ideas. Who knows, we may even learn something in the process. (Image, above, shows what we're all now thinking).

Before we get going, though, some ground rules. Aside from the fact that we’re ignoring pterosaur extinction in this discussion, we’re basing everything else on fact as much as possible. For instance, we’re not ignoring the extinctions of specific pterosaur groups: if they went extinct before the terminal Cretaceous (when pterosaurs as a whole got the evolutionary chop), then they can’t exist in the modern day. Pterosaurs are also the only animals we’re hauling into the Modern: the biosphere is otherwise exactly as it is now, so there are no tyrannosaurs or anything running around as well. Also, the goal here is to consider pterosaurs as real animals, not hyper-aggressive movie monsters, so we don’t need to pay any attention to their Modern interactions with people in virtually all Silver Screen outings (which invariably boil down to said people being attacked and/or eaten) and start with a clean slate of ideas. Got that? On we go, then.

UPDATE: 24/04/12
Just one last rule, following on Mike Taylor's comment, below. I'm also focusing on pterosaurs as we know them in the fossil record, not as we may twist them through selective breeding or other genetic tampering. I guess this is an exercise in simply crashing pterosaurs into the Recent, considering what basic pterosaur palaeobiology would lend itself to in our modern world.

Roll call

The first part of this exercise, of course, is to determine what pterosaurs we would have running around today. Which lineages were present at the end of the Cretaceous that could, potentially, have survived until Recent times? Because pterosaur fossils are found within spitting distance, geologically speaking, of Tertiary rocks we assume that the last of their kind died out in the same mass extinction event that ruined the weekends for 75 per cent of life 65 Ma (Buffetaut et al. 1996), but the majority of pterosaur types were not witness to this event. Pterosaur faunas of the uppermost Cretaceous are almost entirely dominated by azhdarchids, the often gigantic, toothless and long-necked forms made famous by the likes of Quetzalcoatlus and Hatzegopteryx (see sketch, above, for a general guide to their appearance). These famous genera, incidentally, are some of the last pterosaurs we find in the fossil record, so giant pterosaurs are very much in for our consideration here. An incomplete nyctosaur humerus (if you’re not familiar with nyctosaurs, think Pteranodon, but weirder) from Mexico is the only record of non-azhdarchid pterosaurs in Maastrichtian strata (that is, name of the time interval representing the last 5 million years of the Cretaceous, 70-65 Ma), compared to literally dozens of azhdarchid occurrences (Price 1953). The pterosaur fossil record is noted for its incompleteness and preservational biases (Butler et al. 2009), but their reduced diversity at the end of the Cretaceous may not be an artifact of the fossil record as the number of pterosaur-bearing rock units at this time is relatively high, but diversity remains low. In short, then, while we may be able to identify dozens of different pterosaur groups across their evolutionary history, it seems that only the azhdarchids and nyctosaurs would have any hope of meeting us in the modern. (Image, below, shows a phylogenetic tree of pterosaurs using the major clades of Lü et al. [2010] mapped across time. The squiggly line shows the number of pterosaur-bearing rock units throughout the Mesozoic [borrowed from Butler et al. 2009] From my book).

With 65 million years separating us from the last pterosaurs, it is not unreasonable to assume that they may have developed into rather different forms by the time modern man appeared. Or would they? Evolutionary stasis spanning 9 – 10 Ma has recently been proposed for several non-pterodactyloid pterosaur clades (Lü et al. 2012) and, although admittedly suggested by rather fragmentary remains, several pterodactyloid lineages also do not appear to change dramatically over longer time frames. This may be true for azhdarchids as much as anything else: a vertebra representing the oldest known azhdarchid is known from Berriasian rocks of Romania (140 Ma) (Dyke et al. 2010) and looks, so far as I can see, no different from the vertebrae of Maastrichtian forms. Note that azhdarchid necks are very derived compared to those of other pterosaurs, so this comparison of their cervical anatomy suggests that the group was already fairly ‘evolved’ very early on in the Cretaceous. Maybe, then, modern pterosaurs would not be so dissimilar from the forms we know in the fossil record.

Bird brains

What sort of behaviour would we expect of our modern pterosaurs? To best answer this we may want to assess some likely basic aspects of pterosaur physiology and neurology, as this may provide  an insight into how active and intelligent they may have been. There’s scant discussion of pterosaur physiology in pterosaur literature, but their flight adaptations, erect carriage (in at least pterodactyloids, and probably some non-pterodactyloids too), insulating fuzz and relatively large brains all seem to correlate with modern animals that have elevated metabolisms. Pterosaur brains are known from specimens spanning much of their phylogenetic range, and they all seem fairly bird-like, but especially so in later forms (e.g. Witmer et al. 2003; image and caption, below, from this study). There are some differences, such as the pterosaur flocculus (the region of the brain primarily dedicated to motor coordination) being relatively enormous, (perhaps because the muscle-laden wing membranes of pterosaurs were being directly controlled and shaped during flight, requiring some extra computing power [Unwin 2005]), and bird brains are, on the whole, a little larger, but they are otherwise fairly similar. 

It may not be unreasonable, then, to predict that all pterosaurs – including our hypothetical modern ones – would be active, fairly intelligent beasties that, with warm bodies and big brains to fuel, may spend much of their time foraging. This leads us to a further analogy with birds: the requirement for lots of food does not sit well with flight, as a full belly is more mass to shift about. Hence, pterosaurs – like birds – may have dumped their waste as often as possible, presumably in the same form of acidic paste that common to all archosaurs. Such waste can be very damaging to architecture and car paint, so the existence of giant pterosaurs dropping vast quantities of crap on our cool stuff is not an appealing one. Plus, we’ve all been hit by stray bird guano on occasion, which is unpleasant enough, but imagine the same experience when the offending animal is several hundred times the size…

My pet pterosaur, and pterosteaks

As with most things in life, it probably wouldn't be long before the economic potential of Modern pterosaurs was tested. Could we farm them for meat and eggs, or breed them as household pets? Pterosaurs would probably be lousy sources of food for several reasons. The amount of meat offered from pterosaur carcasses is tiny compared to their overall size, providing minimal returns to pterosaur farmers for the space required to rear them. Pterosaurs have tiny, tiny bodies, with their edible soft tissues tightly concentrated around them. Even the biggest azhdarchids probably only had bodies 70 cm long (Witton and Habib 2010) with around 60 kg of flight muscle (Paul 2002), despite standing tall enough to look into a first floor window. Ornithocheiroids are even more disproportionate, with torsos barely longer than their humeri (near-enough the shortest bones in their wings). Some pterosaurs may offer better options, such as the relatively long bodied ctenochasmatoids, but they were long gone before the KT boundary, and therefore out of the game here. 

Keeping ourselves stocked with pterosaurs may require a lot of careful planning as their development times appear more extended than we're accustomed to with modern livestock. Because pterosaurs lay parchment-shelled eggs like most modern reptiles, it’s assumed that they required similarly long incubation periods of two or three months (Unwin and Deeming 2008). Once hatched, it seems that neonate pterosaurs did not rocket to full adult size like modern birds (a trait we’ve artificially enhanced in poultry to have large, fully-grown chickens within weeks of hatching), instead slowing their growth rates once they reach half size (Chinsamy et al. 2008). It's predicted that, for some pterosaurs, this threshold may take several years to reach (Bennett 1995; Chinsamy et al. 2008) As such, we could be looking at several years between pterosaur generations, which is a little on the slow side for big business. We don’t know much about pterosaur clutch sizes or reproductive rates, so it’s not clear how many animals you’d need to sustain a harvestable, breeding population but, regardless, it seems that you’d need a pretty substantial operation to get any profit out of space-demanding animals with awkward reproductive mechanisms.

So, pterosaurs would probably make for lousy food sources, but what about pets? It would certainly be cool to keep your own little azhdarchid that you could take out for a flap, train to fetch the morning paper and perform tricks, but the ‘little’ part may be a problem. Pterosaurs are said to demonstrate Cope’s Rule, the controversial idea that the average body size of individuals within a given lineage will increase over time (Hone and Benton 2007; see graph from this study, above, showing the increase in average pterosaur wingspans over time). Whether you agree with the notion of Cope’s Rule or not, it’s hard to ignore the steady increase in average pterosaur body size throughout the Mesozoic, leading to the smallest known Maastrichtian taxon (the oddly-proportioned Montanazhdarcho) being 2.5 m across the wings. A 2.5 m span may seem small compared to its 10 m span contemporaries but, for a homeowner, it would still be far too large to have in the house. Standing upright, said diminutive azhdarchid would have a shoulder height of over a metre and, with its long neck, be nearly as tall – if not taller - as you. That’s hardly a little animal, and probably one that would scare the bejesus out any other pets you have, and may even see them as potential lunch. Perhaps best to leave the pterosaur wrangling to zoos, then.

The biggie: could I ride a pterosaur to work?

Almost certainly the most important consideration in this concept: were pterosaurs strong enough fliers that we could saddle them up fly them places? Well, possibly.

Pterosaur.Net regulars are no doubt aware that some pterosaur workers now think that pterosaurs launched quadrupedally, using their powerful flight muscles to propel themselves into the air (Habib 2008). Part of the rationale for this idea is the strength of the forelimbs compared to the hindlimbs, as the launching limbs tends to be proportionally large in any flying vertebrate you care to look at over a certain mechanical threshold. As with most animal skeletons, it seems that the pterosaur forelimbs came equipped with large mechanical safety factors to accommodate for any atypically heavy loads that may be placed on the limbs. The humeral safety factors against bending in the largest azhdarchids – which we would possess in the Modern in our hypothetical scenario here, remember – are around 2.5 – 1.8, depending on how heavy you consider the animal to be between 180 - 250 kg (Witton and Habib 2010). Thus, the pterosaur skeleton could take weight of a person without crumpling, but could it take off? It seems so: Marden (1994) calculated that a giant azhdarchid would find launch no more strenuous than a 1 kg vulture, suggesting that one could, theoretically, take on the extra burden of a person on its back. Perhaps only relatively small folks would be suitable pterosaur jockeys to reduce the strain as much as possible but, hey, that’s still something, right?

This is not the end of the story, however. While the azhdarchid may be able to sustain flight with a jockey when flapping vigorously, it would not be able to endure this indefinitely. Mike Habib predicted for our 2010 study that a giant would have a few minutes of burst flight, tops, before it had to rest in a gliding phase. To avoid merely landing at the end of this, an alternative source of lift would be needed, and this is where a potential fly in our ointment appears. Long distance travel for azhdarchids was probably achieved by soaring (Witton and Habib 2010), which would be reliant – as it is with modern birds and bats – on climbing to high altitudes (many thousands of metres in some cases) on uplifts of air before gliding on. This would be a significant problem for our jockeys. Mammals are far less tolerant of hypoxia than birds (and, perhaps, by extension, pterosaurs) and, at altitudes that even little birds like sparrows are alert and lively, mammals are comatose (Faraci 1991). Hence, to fly with azhdarchids we may have needed to curb their flight styles a bit, keeping them at lower altitudes and, presumably, making more frequent use of areas of uplift. Alternatively, we supply them with oxygen tanks and warm clothing to keep them alive, but this all adds weight and reduces our azhdarchid's flight ability. Hmm... perhaps this is more complex than we thought.

Gosh, look at the time. There’s a lot more we could mention about riding pterosaurs, but I think we’ll stop there for now. This has already gone on too long and I’ve not even covered the most exciting bit: living alongside wild pterosaurs. Would we be potential pterosaur prey? Could they be pests of annoyances to us? All things to be discussed soon...

References

Buffetaut, E., Clarke, J. B. and Le Lœuff, J. 1996. A terminal Cretaceous pterosaur from the Corbiéres (southern France) and the problem of pterosaur extinction. Bulletin de la Societe Geologique de France, 167, 753-759.

Butler, R. J., Barrett, P. M., Nowbath, S. & Upchurch, P. 2009. Estimating the effects of the rock record on pterosaur diversity patterns: implications for hypotheses of bird/pterosaur competitive replacement. Paleobiology, 35, 432-446.

Bennett, S. C. 1995. A statistical study of Rhamphorhynchus from the Solnhofen Limestone of Germany: year-classes of a single large species. Journal of Paleontology, 69, 569-580.

Chinsamy, A., Codorniu, L. and Chiappe, L. 2008. Developmental growth patterns of the filter-feeder pterosaur, Pterodaustro guiñazui. Biology Letters, 23, 282-285.

Dyke, G., J., Benton, M. J., Posmosanu, E. and Naish, D. 2010. Early Cretaceous (Berriasian) birds and pterosaurs from the Cornet Bauxite Mine, Romania. Palaeontology, 54, 79-95.

Faraci, F. M. 1991. Adaptations to hypoxia in birds: how to fly high. Annual Review of Physiology, 53, 59-70.

Habib, M.B. 2008. Comparative evidence for quadrupedal launch in pterosaurs. Zitteliana, B28, 161-168.

Hone, D. W. E. and Benton, M. J. 2007. Cope’s Rule in the Pterosauria, and differing perceptions of Cope’s Rule at different taxonomic levels. Journal of Evolutionary Biology, 20, 1164–1170.

Lü, J., Unwin, D. M., Jin, X., Liu, Y. and Ji, Q. 2010. Evidence for modular evolution in a long-tailed pterosaur with a pterodactyloid skull. Proceedings of the Royal Society B, 277, 383-389. 
Lü, J., Unwin, D. M., Zhou, B, Chunling, G, and Shen, C. 2012. A new rhamphorhynchid (Pterosauria: Rhamphorhynchidae) from the Middle/Upper Jurassic of Qinglong, Hebei Provine, China. Zootaxa, 3158, 1-19.

Marden, J. H. 1994. From damselflies to pterosaurs: how burst and sustainable flight performance scale with size. American Journal of Physiology, 266, 1077-1084.

Paul, G. S. 2002. Dinosaurs of the Air: The Evolution and Loss of Flight in Dinosaurs and Birds. John Hopkins University Press, Baltimore, 472 pp.

Price, L. I. 1953. A presença de Pterosáuria no Cretáceo superior do Estada da Paraiba. Divisão de Geologia e Mineralogia Notas Preliminares e Estudos, 71, 1-10.

Unwin, D. M. 2005. The Pterosaurs from Deep Time. Pi Press, New York, 347 pp.

Unwin, D. M. and Deeming, D. C. 2008. Pterosaur eggshell structure and its implications for pterosaur reproductive biology. Zitteliana, B28, 199-207.

Witmer, L. M., Chatterjee, S., Franzosa, J. and Rowe, T. 2003. Neuroanatomy of flying reptiles and implications for flight, posture and behaviour. Nature, 425, 950-953.

Witton, M. P. and Habib, M. B. 2010. On the size and flight diversity of giant pterosaurs, the use of birds as pterosaur analogues and comments on pterosaur flightlessness. PLoS ONE. 5, e13982. 

Does Air Density Make a Difference?

This is essentially a cross-post from H2VP (with some additions)

One thing I have been asked with some regularity is whether or not a somewhat denser Mesozoic atmosphere, particularly in the Cretaceous (compared to the modern one), could explain the giant size of Late Cretaceous pterosaurs or large dinosaurs.  In short, the answer is: probably not.

There is a reasonably good body of information regarding atmospheric composition during the Mesozoic.  During the Cretaceous, both oxygen and carbon dioxide levels rose slightly, and the total atmospheric density would have been slightly greater as a result - but the difference would have been relatively mild for large vertebrates.

Here is an example of a paper published on the effects of Cretaceous oxygen concentrations on plants: http://jxb.oxfordjournals.org/content/52/357/801.full, and there is a manuscript examining the effect of paleoatmosphere conditions on insects: http://jeb.biologists.org/content/201/8/1043.full.pdf.  There is a relatively recent paper on the Late Cretaceous atmosphere and its potential relationship to mass extinction as well: http://jxb.oxfordjournals.org/content/52/357/801.full

As you can see, plants and insects probably felt the effects of slightly higher oxygen and carbon dioxide concentrations, and indeed the insects of the Cretaceous included some relatively large species, as would be expected.  A slight increase in atmospheric density would have relatively little impact on the maximum size of dinosaurs or pterosaurs, however, and there is not actually any need for an extreme explanation for their size, anyway - despite being larger than living animals with similar lifestyles, none of the giant dinosaurs exceeded the expected maximum size for a walking animal, and no pterosaurs exceeded the limits for biological flight.  Quite a few pterosaurs exceeded the estimated limit for continuous flapping flight in a vertebrate animal (limit is roughly 25-30 kg, give or take), but that only means that they could not flap continuously over long distances and would have switched to soaring flight for long trips; it does not forbid them from flying.

There are three reasons why changes in atmospheric conditions have greater impacts on insects than vertebrate flyers.  First, the tracheal system that insects use for respiration is highly sensitive to oxygen partial pressure.  Second, since insects are typically small, they are often highly reliant on unsteady aerodynamics, which are much more sensitive to air density than steady dynamics.  Finally, insects are almost purely aerobic flyers, while many vertebrates can utilize some degree of anaerobic power (in large flying vertebrates, anaerobic power dominates).  Using anaerobic flight muscle provides a very large burst of power, without using oxygen, after which the muscle quickly fatigues.  Large vertebrates can therefore flap for short bursts, followed by periods of gliding, even when oxygen levels are low.  This option is typically unavailable to insects.

Dr. Witton dismisses more evidence for the existence of giant pterosaurs in the Lower Cretaceous

I really liked my English Literature teachers at school. They were extremely laid back, personable folks who treated us like adults, which is a big deal when you’re 16 years old. They encouraged individuality in our interpretations of books and, indeed, my experience with them had me seriously considering teaching English if this palaeontology lark went nowhere. They even bought us books at the end of our A’ Levels that they thought matched our personalities: I got Joseph Conrad’s Heart of Darkness - make of that what you will.

Unfortunately, they didn’t have the easiest ride when teaching me as I used to wind them up without end. Not, you understand, by drawing inflated phalluses on my exercise book, or by never handing assignments in, talking in class or constantly underachieving: no, I was routinely criticised for making them laugh with my essays. Apparently, nicknaming Hamlet ‘Hammy’ wasn’t standard practise and, so I hear, nine essays out of ten did not compare the cast of Volpone to characters from Only Fools and Horses. Likewise, passages in The Handmaid’s Tale weren’t often compared favourably to lyrics from Eurythmics numbers and, generally speaking, calling The Great Gatsby’s Tom Buchanan a douche wasn’t the done thing. Thing is, none of my teachers had any problems with what I was saying, but the way that I expressed myself was just not on. ‘Don’t write like this’, my teachers told me time and again, ‘your examiners won’t appreciate it’. This confused me as a 16 year old and still does now. Do exam markers have no sense of humour? I’ve yet to meet someone who marks GCSE’s and A’ Levels, but, from this, I imagine they must resemble the enjoyment-hating Blue Meanies from The Yellow Submarine, stamping out positivity with rocket-propelled gloves, clown-controlled explosives and apple-lobbing men in top hats. At least, I hope they do: it’s a much more interesting picture than a bunch of sour-faced miseries sitting in grey office cubicles, angrily scribbling over exam copy books in red pen.

Nowadays, the only scribing I do with intentional dryness is for scientific papers (and even this has been described as too florid by some referees). It produces a strange, sub-schizophrenic feeling when writing and reading it, almost like the ‘Witton’ character cited in other papers isn’t really me: he’s some faceless, professional authority on pterosaurs, someone working in a studious, clean office and certainly not writing papers crashed out on his sofa with repeats of Top Gear on the TV and holes in his socks. But no, these people are one and the same and, to prove it, this post features some suitably dry text I had rejected from a chapter I’m coauthoring on Wealden Supergroup pterosaurs with Dave Martill and Steve Sweetman. For those who don’t know, the Wealden Supergroup is a historically significant series of Lower Cretaceous deposits found across southern England and is one of Europe’s top sites for terrestrial vertebrates of this time. The text evaluates claims that some Wealden pterosaur material represents pterosaurs of gigantic proportions and, because it’s hardly significant enough to warrant its own paper and we discussed other claims for gigantic pterosaurs in the Lower Cretaceous several weeks back, it seems like ideal fodder for the Pterosaur.Net blog. Before it starts, though, it’s worth pointing out that if these and my previous musings on these topics are correct, giant (say, 7 m spans and above) are an exclusively Upper Cretaceous phenomenon. OK? Great. Without further ado, then, I hand you over to my concise, authoritative sounding alter ego, Dr. Witton. If anyone needs me, I’ll be in the lounge watching TV and playing with my feet.

Giant pterosaurs in the Wealden Supergroup?


Martill et al. (1996) and Howse et al. (2001) reported on several bone fragments from the Wessex Formation that allegedly revealed the presence of giant pterosaurs – possibly rivalling the 10 – 11 m wingspans of the largest known forms (Langston 1981) - amongst the Isle of Wight assemblage. The most pertinent of these fragments were a poorly preserved distal humerus (ICWMS 1995.631; 75 mm wide, A and B in the adjacent image [from Martill et al. 1996]) and a fragment of proximal first(?) wing phalanx (ICWMS 1995.629; 53 mm minimum width,C and D in the adjacent image) that, although fragmentary, are the largest articular ends of any pterosaur long bones yet reported from the Wealden.

The identity of these bones as giant pterosaurs is questionable, however. Both Martill et al. (1996) or Howse et al. (2001) report the allegedly giant remains as those of indeterminate pterosaurs, but the distal profile of ICWMS 1995.631 corresponds well with the distal humeri of ornithocheiroids (Hooley 1913; Wellnhofer 1985; Kellner and Tomida 2000) and is almost certainly a member of this clade. Accordingly, greater constraint can be placed on its size than previously realised. ICWMS 1995.631 is 17 per cent wider than the (63 mm) distal width of the Istiodactylus humerus reported by Hooley (1913; BMNH R706) but only 5 per cent wider than the same dimension (71 mm) reported for Anhanguera by Kellner and Tomida (2000; NSM-PV 19892). It is also substantially smaller than that of a large Pteranodon (102 mm; Bennett 2001; YPM 1175). The wingspans of these forms can be relatively well constrained at 5 m in the former cases and between 6 – 7 m for the latter. The transverse dimensions of these bones will not equate to proportional increases in humeral length either as pterosaur long bone articulations increase with positive allometry compared to length (for a good graphic example, compare the 5 and 10 -11 m span Quetzalcoatlus humeri figured by Wellnhofer [1991], p. 141). Thus, ICWMS 1995.631 would be negligably longer than the Istiodactylus and Anhanguera humeri mentioned above, suggesting it too was around 5 m in wingspan. It represents, therefore, a relatively large ornithocheirid but a ‘medium’ sized pterosaur overall.

The size of the individual represented by the possible first wing phalanx ICWMS 1995.629 is harder to determine as the specimen itself is hard to identify. Although the thinness of the bone wall indicates it is a pterodactyloid bone, the specimen lacks any features of note bar the expansion of one end and an oval cross section. Such attributes could apply to several pterosaur long bones: the distal half of the humerus, either end of the radius or ulna or the proximal wing metacarpal but, crucially, do not apply to the proximal phalanx of the wing finger. In at least some pterosaurs, these bones have cross sections that resemble rounded triangles, not ovals (Wellnhofer 1985). The identity of ICWMS 1995.629 as a giant pterosaur is dependent on its identification as a proximal wing phalanx as, if it represents another of the elements listed above, its proportions are unremarkable. With an identity as a proximal wing phalanx doubtful, its status as a pterosaurian giant is also unlikely.

Thus, there is no evidence that the Wealden Supergroup contained pterosaurs of particularly gigantic size. While the 5 m span Wealden forms are much larger than any modern flying animals, their wingspans are quite typical of Lower Cretaceous forms and much smaller than the true giants that would evolve later in the Cretaceous.

References

• Bennett, S. C. 2001. The osteology and functional morphology of the Late Cretaceous pterosaur Pteranodon. Palaeontographica Abteilung A, 260, 1-153.
• Hooley, R. W. 1913. On the skeleton of Ornithodesmus latidens; an Ornithosaur from the Wealden Shales of Atherfield (Isle of Wight). Quarterly Journal of the Geological Society, 96, 372-422.
• Howse, S. C. B., Milner, A. R. and Martill, D. M. 2001. Pterosaurs. In: Martill, D. M. and Naish, D. (eds.), Dinosaurs of the Isle of Wight. Palaeontological Association, Field Guide to Fossils 10, pp. 324-335.
• Kellner, A. W. A. and Tomida., Y. 2000. Description of a new species of Anhangueridae (Pterodactyloidea) with comments on the pterosaur fauna from the Santana Formation (Aptian -Albian), Northeastern Brazil. National Science Museum, Tokyo, Monographs, 17, 1-135.
• Langston, W. Jr. 1981. Pterosaurs. Scientific American, 244, 92-102.
• Martill, D. M., Frey, E., Green, M. and Green, M. E. 1996. Giant pterosaurs from the Lower Cretaceous of the Isle of Wight, UK. Neues Jahrbuch fur Geologie und Paläontologie, Monatshefte, 1996, 672-683.
• Wellnhofer, P. 1985. Neue pterosaurier aus der Santana-Formation (Apt) der Chapada do Araripe, Brasilien. Palaeontographica. Abteilung A, 187, 105-182.
• Wellnhofer, P. 1991. The Illustrated Encyclopedia of Pterosaurs. Salamander Books Ltd., London. 192 pp.

Gorgonophilia, Star Trek and how they relate to giant pterosaurs in the Lower Cretaceous

I was very happy to find that my airline had provided me with my own little TV screen and a selection of movies for my flight back from Flugsaurier 2010. With eight hours to kill, this was welcome news and, as soon as we were away and provided with those annoying little earbud headphones that never really fit your ears properly, I was off to Movieland. First up: the remake of Clash of the Titans, a flick that I’d not heard great things about but promised nice visuals, minimal cerebral action and plenty of nice CG creatures. The reviews I’d read were spot on: clichéd characters, dialogue so wooden it could serve as a useful boat oar and numerous clumsy attempts to cash in on the 3D bandwagon kicked off by Avatar. Still, it did feature a nicely rendered Pegasus, giant scorpion caravans and Medusa, a snake-woman hybrid that I found worryingly attractive. Most concerning is that it wasn’t just the top half that made for the most pleasant viewing (which would be understandable, given that her appearance was based on model Natalia Vodianova): there’s clearly a part of my psyche, unrecognised until a week or so ago, that really digs the thought of scantily-clad snakewomen sliding and coiling around their room and constricting visitors to their chambers. Imagine how touchy-feely that would be: you’d not mind having a late breakfast with that. Man, that' d be a night to remember. Just think of the... oh… wait a second. Oh yeah: pterosaurs. Blog post. Decency. No mythophilic filth. Got it.

Next up: last year's Star Trek reboot. Now, I’ve never seen eye-to-eye with Star Trek. I was once a massive fan of Star Wars, but Trek? No. Just couldn’t get into it. Lots of talking; uniforms that looked a bit like the pyjamas I used to wear; big, lumbering spaceships that fire weedy looking weapons; aliens that look just like people with pies glued to their foreheads and, most importantly, a distinct lack of Han Solo. Bottom line: I just found it a bit dull so, when I heard the whole thing was being rebooted I wasn’t terribly excited by the idea. Still, the reviews were pretty good so I thought I’d give it a whirl. I did, after all, have several hours of flight time to kill.

You know what? It was great. It was exciting. It had proper aliens and gripping, tense action scenes. It had Simon Pegg. It wasn’t clean cut: there was even a bit of proper, honest-to-goodness swearing. I was totally surprised and, while I’m unlikely to change my opinion on the other entries in the franchise, I’ll certainly give the 2012 Trek sequel a spin. I may even pay to see it at the cinema. You know: with my own money and everything.

And the new Star Trek is just like pterosaur specimen n. 12701a of the Ligabue collection


Seriously. For the uninitiated, n. 12701a is a tiny distal fragment of a pterosaur wing phalanx one from the Santana Formation of Brazil (described by Dalla Vecchia and Ligabue 1993; n. 12701a shown in adjacent line drawing). When I say fragment, I’m not kidding: it’s really is one of the most unremarkable, dull and uninteresting scraps of pterosaur fossil ever published on and, like the old Star Trek, it’s the sort of thing that we should only really be bothered about when there’s no reruns of The Simpsons on the telly. In fact, probably the only thing stopping n. 12701a from being totally forgotten about is its size: for a distal fragment of a wing phalanx, it’s huge. At 75 mm across, Dalla Vecchia and Ligabue reconstructed the length of the complete phalanx as 850 mm (based on ornithiocheiroids such as Pteranodon and Santanadactylus), a dimension almost twice the size of comparable elements from 4 -5 m span ornithocheirids. Using complete ornithocheirid wings as a guide, the authors then went on to suggest that tiny-little-fragment n. 12701a represents an animal with a whopping 8 – 9 m wingspan.

Now, in a world where the largest pterosaurs span something like 10 m, the predicted wingspan of n. 12701 isn’t really a big deal. What is, however, is its age: aside from this and some other problematic remains from Britain*, there are no accounts of giant pterosaurs in the Lower Cretaceous. Hence, n. 12701 suggests that sizes pretty-near comparable with the largest pterosaurs of all were achieved tens of millions of years before Pteranodon and the giant azhdarchids turn up. All of a sudden, then, that chunk of pterosaur is starting to look far less pre-2009 Star Trek-esque and far more akin to the 2009 reboot: it's exciting, interesting and, being the lone wolf for giant pterosaurs of this time, a touch edgy. Indeed, people have probably been getting excited about n. 12701a for some time: I wouldn’t be surprised if it influenced the decision to portray Ornithocheirus with a 10 m span in Walking with Dinosaurs, for instance (see image at the top of the post, from here).

*There is one additional claim for giant pterosaurs in the Lower Cretaceous based on very, very scrappy material from the Isle of Wight, UK (Martill et al. 1996). We don’t have time to go into the details here, but there’s good reason to think that these remains were not from giant animals. The rationale for this has been written up by myself, Dave Martill and Steve Sweetman and should be published next year.

Alas, n. 12701a may not be quite as New Trek as we all thought. To be honest, I’ve never been fully convinced that it demonstrated giant pterosaurs were present in the Lower Cretaceous: it’s just so scrappy that drawing any conclusions about its overall size seems extremely spurious. A little bit of further investigation reveals why this gut feeling may be right.

That was then: this is now
To begin with, there no way that n. 12701a can be allocated to any pterosaur group: it’s just too scrappy and undiagnostic (Dalla Vecchia and Ligabue stated this themselves, but it bears reiterating here because it will prove important later). It is probably sensible to suspect it represents a group known from the Santana Formation, meaning it could either represent an ornithocheirid or an azhdarchoid. Now, in 1993, the Santana Formation was mainly known for its ornithocheirids (e.g. Unwin 1988) and azhdarchoids were relatively new kids on the block (Kellner and Campos 1988; Kellner 1989). Since then, however, we’ve found much more azhdarchoid material including up to three new species (Kellner and Campos 1994, 2002; Witton 2009), complete skeletons (Kellner and Hasagawa 1993) and buckets of incomplete specimens that are sitting in museum stores. This suggests that azhdarchoids were a far more speciose and abundant component of the Santana Formation pterosaur assemblage than could be predicted in the early ‘90s, then, and this is means that we need to strongly consider that n. 12701a may have azhdarchoid affinities.


This is potentially quite a big deal because azhdarchoids and ornithocheirids have very different wing constructions (see diagram of pterodactyloid wing configurations, above. The top image shows the ornithocheirid wingplan; middle image, the azhdarchid wingplan; bottom, tapejarid wingplan. From Witton [2007]). The wing phalanges of ornithocheirids are far more proportionate along the length of the wing finger, decreasing in size distally but only by comparatively small measures (e.g. Wellnhofer 1985). Azhdarchoids, by contrast, have massive first phalanges in their wing fingers (occupying over 40 per cent of the total finger length) but then drastically reduced second, third and fourth elements (Unwin 2003; Kellner 2003). What’s more, the diameters of the distal wing phalanges decrease in size dramatically across the azhdarchoid wing: that of the first is proportionally enormous compared to the rest. What this is leading up to, then, is that an azhdarchoid could have a massive first wing phalanx like that represented by n. 12701a without being a pterosaur giant. In fact, scaling an azhdarchoid wing using the 850 mm-long first phalanx length predicted by Dalla Vecchia and Ligabue gives a single wing length of just 3 m, and, therefore, a total wingspan of 6 m. That’s big, sure, but hardly gigantic for a pterosaur. Plus, this estimate supposes that the 850 mm length reconstuction of n 12701a is appropriate: would the same estimate be generated if it were based on a non-ornithocheirid pterosaur?


The plot thickens further when we consider that large azhdarchoids are already known from the same locality as n. 12701a. The Santana Formation thalassodromid Thalassodromeus, in particular, is a huge animal with a jaw approaching a metre in length (see image, above, of the author posing in a most embarrassing fashion with a full-size Thalassodromeus bust). Estimating the wingspan for this animal is difficult as no postcranial material is known, but its skull proportions suggest a 5 m span (Kellner and Campos 2002). Given how little data we have regarding the proportions between neoazhdarchian skulls and wingspans, it may not be entirely crazy to suppose a 6 m wingspan, either. Along with everything else, then, there are pterosaurs in the Santana Formation that would be a good size match for n. 12701a if it were, indeed, an azhdarchoid.

So, Lower Cretaceous giant pterosaurs, then?
None of this delivers a death-blow to the idea of giant pterosaurs existing in the Lower Cretaceous of course, but it certainly suggests that there is an equally, if not more, parsimonious interpretation of n. 12701a than it being the sole remnant of a giant ornithocheirid species. If nothing else, ornithocheirids are among the best represented of all pterosaurs and, in our extensive sampling of them, there’s no other evidence for such enormous animals (at least, none that I’m aware of). Considering n. 12701a as an azhdarchoid is a far more believable interpretation: it scales to a wingspan that we know azhdarchoids achieved, we would expect its overly large proportions in an azhdarchoid wing and, indeed, there are even comparably sized azhdarchoids in the same deposit. As such, while I’m not going to rule out the evolution of giant pterosaurs in the Lower Cretaceous entirely, I think we need far more evidence that we currently have to consider their existence likely.

And that, folks, is it for now. It’s Saturday night, so I’ll take my tale of how n. 12701a went from being boring to being really exciting and then boring again to the pub. Hey, you never know: there may be some women down there that, from the waist down, resemble rattlesnakes. You never know. I need to get ready. Clean, ironed shirt? Check. Wallet, house keys and phone? Check. Reflective shield and anti-venom? Check. Right, toodles.

References

• Dalla Vecchia, F. M. and Ligabue, G. 1993. On the presence of a giant pterosaur in the Lower Cretaceous (Aptian) of Chapada fo Arariple (northeastern Brazil). Bollettino della Scoietá Paleontologica Italiana, 32, 131-136.
• Kellner, A. W. A. 1989. A new edentate pterosaur of the Lower Cretaceous of the Araripe Basin, Northeast Brazil. Anais da Academia Brasileira de Ciências, 61, 439-446.
• Kellner, A. W. A. 2003. Pterosaur phylogeny and comments on the evolutionary history of the group. In: Buffetaut, E. and Mazin, J. M. (eds.) Evolution and Palaeobiology of Pterosaurs, Geological Society Special Publication, 217, 105-137.
• Kellner, A. W. A. and Campos, D. A. 1988. Sobre um novo pterossauro com crista sagital da Bracia do Araripe, Cretáceo Inferior do Nordeste do Brasil. Anais da Academia Brasileira, Ciências, 60, 459-469.
• Kellner, A. W. A. and Campos, D. A. 1994. A new species of Tupuxuara (Pterosauria, Tapejaridae) from the Early Cretaceous of Brazil. Anais da Academia Brasileira, Ciências, 66, 467–473.
• Kellner, A. W. A. and Campos, D. A. 2002. The function of the cranial crest and jaws of a unique pterosaur from the Early Cretaceous of Brazil. Science, 297, 389-392.
• Kellner, A. W. A. and Hasagawa, Y. 1993. Postcranial skeleton of Tupuxuara (Pterosauria, Pterodactyloidea, Tapejaridae) from the Lower Cretaceous of Brazil. Journal of Vertebrate Paleontology, 13, 44A.
• Martill, D. M., Frey, E., Green, M. and Green, M. E. 1996. Giant pterosaurs from the Lower Cretaceous of the Isle of Wight, UK. Neues Jahrbuch fur Geologie und Paläontologie, Monatshefte, 1996, 672-683.
• Unwin, D. 1988. New pterosaurs from Brazil. Nature, 332, 398-399.
• Unwin, D. M. 2003. On the phylogeny and evolutionary history of pterosaurs. In: Buffetaut, E. and Mazin, J. M. (eds.) Evolution and Palaeobiology of Pterosaurs, Geological Society Special Publication, 217, 139-190.
• Wellnhofer, P. 1985. Neue pterosaurier aus der Santana-Formation (Apt) der Chapada do Araripe, Brasilien. Palaeontographica. Abteilung A, 187, 105-182.
• Witton, M. P. 2007. Titans of the skies: azhdarchid pterosaurs. Geology Today, 23, 33-38.
• Witton, M. P. 2009. A new species of Tupuxuara (Thalassodromidae, Azhdarchoidea) from the Lower Cretaceous Santana Formation of Brazil, with a note on the nomenclature of Thalassodromidae. Cretaceous Research, 30, 1293-1300.