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Image from Naish & Witton 2017[/caption]
Looking through my article categories it would seem that I've never blogged about prehistoric creatures at all on this site, which is frankly ridiculous. As such, a post such as this one is well past due. Plus the subject matter, in my opinion, is ridiculously cool (that likely says more about me than the source material, though).
I've followed Darren Naish's ideas on Azhdarchid behaviour very closely over the past few years, partly because I'm generally a fan of Naish's work and partly because the concept is just very exciting to me. The popular image of pterosaurs rarely expands beyond the concept of reptilian, bat winged flying creatures that were ultimately a poor man's bird, replaced by the evolutionary advancements made by their avian (distant) cousins. Of course, that's a load of nonsense: pterosaurs, of all sorts, were fascinating creatures that occupied a huge variety of niches and continued to be highly successful for millennia after birds first evolved. Not only were they incredibly varied, but they often branched out into niches that today's birds can barely scrape, achieving evolutionary feats that have never been paralleled.
Arguably, one of the clearest examples of pterosaur splendour is the most well known Azhdarchid: Quetzalcoatlus. Famous for its gigantic wingspan, most likely topping out somewhere around 11m, Quetzalcoatlus and its kin are far more interesting than merely boasting the largest wings to have ever evolved. The Azhdarchids are also a bit of an enigma.
Their huge wing spans and, in general, huge sizes have never fit well with the more archaic notion of pterosaurs as bird analogues. When we look at living (or even extinct) birds, the closest niche that seems to fit is that currently embodied by the albatrosses: huge winged ocean wanderers, gliding for days over the waves and feeding on the wing. Azhdarchids are certainly well designed for long-haul gliding, likely (again) being the best long distance gliders to have ever evolved, but they don't fit as albatross analogues because they largely didn't live near the sea.
The vast majority of Azhdarchid remains are found in continental interiors, far from evidence of large bodies of water, so the traditional interpretation of them as oceanic just doesn't make a lot of sense. Naish and Mark Witton are two of the more prominent figures putting forward an alternative theory: Azhdarchids as giant, terrestrial land striders. Storks or secretary birds would become their closest living analogues, but these pterosaurs simply outflank all modern birds in terms of size. To quote Naish directly from his latest blog post on the matter:
Small dinosaurs – up to the size of humans – were very plausibly on the menu for this animal.
Here Naish is referring to a more recent discovery, the robust Romanian Azhdarchid Hatzegopteryx, but increasingly it seems similar to other ideas being put forward at the edges of the scientific community. Indeed, in their latest paper on the matter, Naish and Witton advance an even more radical concept: Hatzegopteryx as the top predator in its ecosystem. It's an idea I absolutely love and one I will continue to follow closely, both in the technical literature (where possible) and in popular science reporting (which has a tendency to lag somewhat). I may even, in the future, use the Azhdarchids as part of another project I'm working on. At any rate, the concept of these gigantic pterosaurs being not only terrestrial predators but potentially sitting at-or-near the top of their respective food chains is just another example of how, often, pterosaurs just outclass modern birds.