Embarrassing questions on Quetzalcoatlus

You can’t queue up at a supermarket checkout nowadays without being bombarded by celebrity lifestyle magazines. They glare at you from the impulse-buy shelves with paparazzi shots of stars looking flabby, pregnant, boozy or unhappy and garish, block capital headlines scorn celebs for revealing their mortal flaws. There is probably a deep-seated psychological reason to their popularity, perhaps reflecting the desire people have for gossip or reassuring somewhat insecure readers that it’s OK, people with stars on Hollywood Boulevard aren’t perfect either. The thing that strikes me, though, is that a lot of the people splashed all over the front pages of these rags have very little substance behind their fame, becoming famous because they took they posed semi-nude for a tabloid newspaper, are related to someone else in the public eye or appeared on telly for five minutes on a reality TV show. These are the empty celebrities, the ones that you assume have some reason for being known but, when investigated in more detail, are actually quite devoid of substance. It’s rare that these tabloid-fodder achieve international fame: to do that, you’ve at least got to be associated with an internationally-released product or hung-out in high-profile political circles. In some respects, then, becoming a real international household name requires a little more substance than your local, lower-grade celebrities. Talent, though, is handy but not strictly necessary.

There are definitely fossil animals that are the equivalent of A-list celebs, the sort of critters that every five year-old knows and that press releases strive to mention, no matter how tangential their work is to them, to gain more kudos. They’re the animals that the public know and love, the likes of Tyrannosaurus, Triceratops, woolly mammoths and sabre-toothed cats. Typically, these animals do have some substance to them: while their taxonomy may be confused or controversial, they definitely ‘exist’. Some pterosaurs are in this club too, with Pterodactylus (or probably ‘pterodactyls’) or Pteranodon being at the top of the list, and Quetzalcoatlus, everyone’s favourite superpterosaur, just behind (detail of a new image above). Thing is, though, Quetzalcoatlus may be a fraud. Yes, that’s right: there may be so little substance to its existence that its status as a household palaeontological name is undeserved: it’s a local celeb masquerading as a big shot. That’s controversial stuff and, no doubt, several of you have just sprayed your monitor with coffee shot through your nose at the very idea of such a thing. But mop up that liquid, dry the screen off, and we’ll see why I’m suddenly being so nasty to one of the cornerstones of Azhdarchidae.


Giant, yes; diagnostic, maybe not
As I’m sure you all know, Quetzalcoatlus stems from the Maastrichtian Javelina Formation of Texas. Remains of several animals that would be referred to this genus were found from 1972 – 1974 and were briefly described by their discover, Douglas Lawson, in 1975 (Lawson 1975a). Quetzalcoatlus was erected in the same year (Lawson 1975b) with fragments of a giant left wing (including a famous complete humerus, TMM 41450-3; see image, above) being used as the holotype for the type species, Q. northropi Lawson, 1975b. A bunch of smaller individuals that were represented by substantially more complete remains were discovered at the same time and initially referred to the same species (Lawson 1975a, b) but, later, were said to be sufficiently distinct from Q. northropi to deserve their own species (Kellner and Langston 1996). Pending their complete description, however, Kellner and Langston simply called them ‘Q. sp.’ for their work on the Quetzalcoatlus skull.

That all looks above board on the surface, but it doesn’t take much digging to find several massive holes. Firstly, despite the wealth of material that has been referred to it, neither Quetzalcoatlus or Q. northropi have ever been given a rigorous taxonomic definition*. To my knowledge, only Nesov (1991) has had a stab at a Quetzalcoatlus definition but his listed characters are either not unique to Quetzalcoatlus or of questionable validity, so his work is not really useful here. This leaves us without a diagnosis and, accordingly, we simply cannot know if Q. northropi is a valid species or not. What’s more, with Q. northropi being the type species of Quetzalcoatlus, the entire genus must go if the former is sunk.

*You could get away with this sort of stuff in the 1970s, but it’s much harder to be taxonomically slack nowadays. The ICZN (the body that regulates naming of zoological specimens) has recently tightened its rules considerably to make sure that new taxa come with proper holotype allocation, diagnoses and all other due practises (e.g. article 16, International Commission on Zoological Nomenclature 1999), so messes like the one under discussion here should – in theory – eventually become a thing of the past.

In my eyes, this is quite a real possibility. Pterosaur limb elements aren’t normally named because they are not considered diagnostic at generic or species levels: taxa that are based on limb elements alone have been considered nomina dubia by later authors. ’Santanadactylus’ spixi - a set of wrist bones - and Palaeornis cliftii - an isolated humerus – have both fallen into this trap (Unwin 2003; Witton et al. 2009). Unless Q. northropi is unusually distinctive, it’s possible it may be binned too. Adding more concern to this worryfire is that, so far as I can see, the Q. northropi humerus doesn’t look that different from other giant azhdarchid humeri (e.g. Padian and Smith 1992; Buffetaut et al. 2002) and the existence of these other giants nullifies the possibility of using size as a diagnostic feature (though this would be dodgy anyway). The other Q. northropi elements are so scrappy that they’re probably of very little taxonomic utility and preclude the use of limb element proportions in a diagnosis, too. Call me cynical if you like, but it looks like this could be an uphill struggle to me.


The plot thickens
There’s more. With no definition for Quetzalcoatlus, the referral of the Q. sp. material (including that depicted above, from Kellner and Langston 1996) to this taxon is also questionable. The Q. sp. material is what people refer to when talking about the detailed anatomy of Quetzalcoatlus, but we need to be careful: there has never been any justification printed for the allocation of Q. sp. to Quetzalcoatlus: we’ve just been told it’s similar to Q. northropi and can therefore be placed in the same genus. Thing is, Hatzegopteryx, Arambourgiania and Zhejiangopterus are pretty similar animals to Q. northropi too, so why can’t the Q. sp. material been popped in one of these genera instead? You can't argue taxonomic provinence in this instance, either: it's highly likely that there is more than one azhdarchid genus in the Javelina Formation (see my thoughts on this here), so you can’t suggest allocation of Q. sp. to Quetzalcoatlus through association alone.

To be clear, I'm not saying that Q. sp. itself is of questionable validity - whatever you want to call it, Q. sp. is definitely a valid, diagnosable species, I’m just iffy about its allocation to Quetzalcoatlus at present. Note, however, that the story continues outside of material referred to Quetzalcoatlus, too: the status of Hatzegopteryx may also hang in the balance. I don’t have time to go into that now, though.

So, what next?
The resolution of all this is, in my view, quite straightforward. Eagle-eyed readers may have read between the lines of this post and realised that, despite it’s fame, popularity and unearthing almost 40 years ago, there is almost nothing written or illustrated of Quetzalcoatlus. The issues highlighted here will not be resolved without this data and, frankly, a few good photographs and descriptions of Q. northopi would give all the information we need to get started. There is, in fact, a bit of an elephant in the room about Quetzalcoatlus and, foolish though it may be for a bloke looking for a job in the pterosaur corner of palaeoindustry to be so outspoken, it should be flagged up. Without mentioning any names, the Texas Memorial Museum has placed a strict embargo on the release of information about Quetzalcoatlus until the full monographic description has been properly published. This has been promised since at least the 1980s (Langston 1981; Kellner and Langston 1996) and, in the meantime, getting access to the material seems to be extremely difficult. I asked to see the material back in 2006 and was told no. Colleagues of mine have asked the same, and got the same answer. The few friends of mine that have seen the specimens are sworn to secrecy and, if they want to publish even itty-bitty snippets of information about them, they have to ask permission first.

If you ask me, this is all a bit rotten. The Society of Vertebrate Paleontology’s ethical mission statement states that vertebrate palaeontologists of the world are here to:

1. To advance the science of vertebrate paleontology throughout the world;
2. To serve the common interests and facilitate the cooperation of all persons concerned with the history, evolution, ecology, comparative anatomy and taxonomy of vertebrate animals, as well as the field occurrence, collection and study of fossil vertebrates and the stratigraphy of the beds in which they are found;
3. To support and encourage the discovery, conservation and protection of vertebrate fossils and fossil sites;
4. To foster the scientific, educational and personal appreciation and understanding of vertebrate fossils and fossil sites by avocational, student and professional paleontologists and the general public.
   

From the SVP Constitution, Article 12, Code of Ethics.

Aside from the point 3 in this list, it seems that the decades-long embargo on the Quetzalcoatlus material isn't really in keeping with these guidelines. I mean, I get embargoes. I get 'gentlemen's agreements' about publishing rights. But 40 years to publish a specimen description while simultaneously being very cagey about giving access to the material? Seriously guys, what's going on? I'm not sure there's quite enough ground here to go stampeding to the SVP ethics committee or anything, but when is this material going to be properly published and freely available to see?

References

• 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.
• International Commission on Zoological Nomenclature. 1999. International Code of Zoological Nomenclature (4th Edition). The International Trust of Zoological Nomenclature, 1999.
• Kellner, A. W. A. and Langston, W. Jr. 1996. Cranial remains of Quetzalcoatlus (Pterosauria, Azhdarchidae) from Late Cretaceous sediments of Big Bend National Park. Journal of Vertebrate Paleontology, 16, 222-231.
• Langston, W. Jr. 1981. Pterosaurs. Scientific American, 244, 92-102.
• Lawson, D. A. 1975a. Pterosaur from the Latest Cretaceous of West Texas: discovery of the largest flying creature. Science, 185, 947-948.
• Lawson, D. A. 1975b. Could pterosaurs fly? Science, 188, 676-677.
• Nesov, L. A. 1991. Gigantskiye lyetayushchiye yashchyeryi semyeistva Azhdarchidae. I. Morfologiya, sistematika. Vestnik Leningradskogo Gosudarstvennogo Universiteta. Seriya 7, 2, 14-23.
• Padian, K. and Smith, M. 1992. New light on Late Cretaceous pterosaur material from Montana. Journal of Vertebrate Paleontology, 12, 87-92.
• 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.
• Witton, M. P., Martill, D. M. and Green, M. 2009. On pterodactyloid diversity in the British Wealden (Lower Cretaceous) and a reappraisal of “Palaeornis” cliftii Mantell, 1844. Cretaceous Research, 30, 676-686.