What’s the deal with your wacky tail-club, Shunosaurus?

June 11, 2010

In a comment on an earlier article, What’s the deal with your wacky postparapophyses, Shunosaurus?, brian engh asked:

What’s the deal with most Shunosaur “life restorations” showing spikes on the tail club? I can’t find a picture anywhere of a skeleton with any indication of spikes, and yet almost every fleshed-out illustration of Shunosaurs has spikes on it’s tail. Anybody know what that’s about?

It seems we’ve never actually featured the famous Shunosaurus tail-club here before — an amazing oversight, and one that I’m going to remedy right now, thanks to Dong et al. (1989).  This short paper is written in Chinese, so I can’t tell you anything beyond what’s in the figures, captions and English-language abstract.

First up, though, here is his illustration of the famed tail-club:

I can’t help noticing, though, that although the fused clump of enlarged distal caudal vertebrae constitutes a nice club, it’s noticably devoid of spikes.  So it remains a mystery why so many restorations show a spiked club.  Anyone out know why?

Dong et al. (1989) also obligingly includes a figure of the tail-club of Omeisaurus:

And also a photographic plate showing both clubs (though, as is so often the case, the scan has lost a lot of details):

Now, the big question is: why do Shunosaurus and Omeisaurus — and Mamenchisaurus, for that matter — have tail-clubs when they are not closely related, according to modern phylogenies such as those of Wilson (2002) and Upchurch et al. (2004)?  [To be precise, Wilson (2002:fig. 13) had Omeisaurus and Mamenchisaurus clading together, but that clade well separated from Shunosaurus; and Upchurch et al. (2004:fig. 13.18) had all three separate, though with the former two as consecutive branches on the paraphyletic sequence leading to Neosauropoda.]

One possibility is just sheer coincidence: but it’s asking a lot to believe that of the 150 or so known sauropods, the only three for which tail-clubs are known just happened to live more or less at the same time and in the same place.

Another option is some oddity in the environment that strongly encouraged the evolution of tail clubs.  Yes, this is wildly hand-wavy, but you can sort of imagine that maybe all the local theropods thought it was cool to hunt sauropods by biting their tails, and the clubs evolved in response to that.  Or something.  There’s a similar, but even more mystifying, situtation in the late Early Cretaceous Sahara, where the theropod Spinosaurus, the ornithopod Ouranosaurus and arguably even the sauropod Rebbachisaurus all evolved sails.  Why then?  When there?  No-one knows and no-one’s even advanced a hypothesis so far as I know.

Getting back to Jurassic Chinese sauropod tail-clubs, though, there is a third option: could it possibly be that Shunosaurus, Omeisaurus and Mamenchisaurus all form a clade together after all, as proposed back in the day by Upchurch (1998:fig. 19)?  Upchurch’s pioneering (1995, 1998) analyses both recovered a monophyletic “Euhelopodidae” — a clade of Chinese sauropods that included the three genera above plus the early Cretaceous Euhelopus, also from China.  The existence of this clade was one of the two major points of disagreement between Upchurch’s and Wilson’s phylogenies (the other being the position of the nemegtosaurids, Nemegtosaurus and Quaesitosaurus, which Upchurch placed basally within Diplodocoidea but Wilson recovered as titanosaurs).

Upchurch himself has abandoned the idea of the monophyletic Euhelopodidae, as seen in that 2004 analysis and also in Wilson’s and his joint (2009) reassessment of Euhelopus: everyone now agrees that Euhelopus is a basal somphospondyl, i.e. close to Titanosauria, which is a looong way from the basal position that the other Chinese sauropods hold within Sauropoda.)  And so the name Euhelopodidae is no longer used.  But could it be that Upchurch was half-right, and that when Euhelopus is removed that the group that was named after it, a clade remains?

[If so, then that clade is called Mamenchisauridae: as noted by Taylor and Naish (2007), this name was coined by Young and Zhao (1972) and so has priority over the Omeisauridae of Wilson (2002), as Wilson himself now recognises.  Mamenchisauridae was phylogenetically defined (or, as they have it, “diagnosed”) by Naish and Martill (2007:498) as “all those sauropods closer to Mamenchisaurus constructus Young, 1954 than to Saltasaurus loricatus Bonaparte”.]

As already noted, Omeisaurus and Mamenchisaurus are close together in the recent analyses of both Upchurch and Wilson, so the question becomes: how many additional steps are required to recover Shunosaurus as a member of their clade rather than in its usual more basal position (in the the case of Upchurch’s analysis, to move Omeisaurus up a node)?  And to this, I do not know the answer — to the best of my knowledge, it’s never been tested (or if it has, the result has never been published).  I’d test it myself, but I need to stop working on this post and watch Inca Mummy Girl soonest.  If , say, 20 additional steps are needed, then forget it.  But if we only need, say, three steps, then maybe someone should look at this more closely.  Back in 2004, when he was Young And Stupid, Matt Wedel wrote to me, in a private email which I now quote without permission because I am pretty sure he’s not going to sue me:

Now that I’ve defended the status quo [of using unweighted characters in cladistic analysis], there are some things I’d be happy to bend the rules for.  If an Omeisaurus pops up with a tail club, then Wilson and Sereno be damned, Omeisaurus and Shunosaurus belong in the same clade. […] So my final word is unweighted characters, please, except for sauropod tail clubs.

Food for thought.

Finally, I leave you with the skeletal reconstruction of Omeisaurus from Dong et al. (1989:fig 3).  Long-time readers will notice a more than passing resemblance to the reconstruction from He et al. (1988:fig. 63), which you can see in Omeisaurus is Just Plain Wrong.

It looks very much as though Dong et al. produced their reconstruction by flipping that of He et al. horizontally and pasting on a tail-club.  Well, we can’t hold that against them — I’d have done the same.

References

  • Dong Zhiming, Peng Guangzhao and Huang Daxi. 1988. The Discovery of the bony tail club of sauropods. Vertebrata PalAsiatica 27(3):219-224.
  • He Xinlu, Li Kui and Cai Kaiji. 1988. The Middle Jurassic dinosaur fauna from Dashanpu, Zigong, Sichuan, vol. IV: sauropod dinosaurs (2): Omeisaurus tianfuensis. Sichuan Publishing House of Science and Technology, Chengdu, China. 143 pp. + 20 plates.
  • Naish, Darren, and David M. Martill. 2007. Dinosaurs of Great Britain and the role of the Geological Society of London in their discovery: basal Dinosauria and Saurischia. Journal of the Geological Society, London, 164: 493-510. (Bicentennial Review issue.)
  • Taylor, Michael P. and Darren Naish. 2007. An unusual new neosauropod dinosaur from the Lower Cretaceous Hastings Beds Group of East Sussex, England. Palaeontology 50 (6): 1547-1564. doi: 10.1111/j.1475-4983.2007.00728.x
  • Upchurch, Paul. 1995. The evolutionary history of sauropod dinosaurs. Philosophical Transactions of the Royal Society of London Series B, 349: 365-390.
  • Upchurch, Paul. 1998. The phylogenetic relationships of sauropod dinosaurs. Zoological Journal of the Linnean Society 124: 43-103.
  • Upchurch, Paul, Paul M. Barrett and Peter Dodson. 2004. Sauropoda. pp. 259-322 in D. B. Weishampel, P. Dodson and H. Osmólska (eds.), The Dinosauria, 2nd edition. University of California Press, Berkeley and Los Angeles. 861 pp.
  • Wilson, Jeffrey A. 2002. Sauropod dinosaur phylogeny: critique and cladistic analysis. Zoological Journal of the Linnean Society 136: 217-276.
  • Wilson, Jeffrey A. and Paul Upchurch. 2009. Redescription and reassessment of the phylogenetic affinities of Euhelopus zdanskyi (Dinosauria – Sauropoda) from the Early Cretaceous of China. Journal of Systematic Palaeontology 7: 199-239. doi:10.1017/S1477201908002691
  • Young, Chung-Chien, 1954. On a new sauropod from Yiping, Szechuan, China. Acta Palaeontologica Sinica II(4):355-369.
  • Young, Chung-Chien, and X. Zhao. 1972. [Chinese title. Paper is a description of the type material of Mamenchisaurus hochuanensis]. Institute of Vertebrate Paleontology and Paleoanthropology Monograph Series I, 8:1-30. English translation by W. Downs.
Posted by Mike Taylor
Filed in caudal, fusion, mamenchisaur, Shunosaurus, Sino-pods, skeletal reconstructions, thagomizer
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Notes on Early Mesozoic Theropods and the future of zoological nomenclature

June 8, 2010

The big noise on the Dinosaur Mailing List at the moment is this thread about Rob Gay’s newly self-published book Notes on Early Mesozoic Theropods, which you can buy from print-on-demand house lulu.com.  (You can also pay to download a PDF if you prefer.)

The interesting thing about about this book is that it contains nomenclatural acts — specifically it names the new theropod Kayentavenator elysiae.  But is this act valid according to the ICZN?  Opinions differ.  The fact that the work was self-published is irrelevant — the Code simply doesn’t care about that.  Beyond this, in the book itself, Gay contends that:

Those that are concerned about the naming of a new genus in this format should not be. The availability and distribution requirements are more than met—the relevant institutions have received a copy for their records. In addition “Notes on Early Mesozoic Theropods” will remain available to all who wish to purchase it online, as well as those stores that chose to carry it, for the foreseeable future—far surpassing the availability of many other high profile publications to those anywhere on the globe.

He feels that this satisfies the relevant articles of the code:

8.1. Criteria to be met. A work must satisfy the following criteria:

  • 8.1.1. it must be issued for the purpose of providing a public and permanent scientific record,
  • 8.1.2. it must be obtainable, when first issued, free of charge or by purchase, and
  • 8.1.3. it must have been produced in an edition containing simultaneously obtainable copies by a method that assures numerous identical and durable copies.

The first thing to say is that Gay would have done himself a favour if his preface had discussed these articles specifically and explained how he felt they were fulfilled: by making only the more general statement above, he’s left matters more open to discussion; or at least forfeited the opportunity to get in a good, strong, opening statement in the inevitable debate.

My own feeling, based on a couple of years on the ICZN mailing list and having witnessed many such discussions between the Commissioners and other specialist nomenclaturists, is that a print-on-demand publication like this does not meet requirement 8.1.3 (“simultaneously obtainable copies by a method that assures numerous identical and durable copies”) — it’s because of this requirement that PLoS ONE has had to adopt its frankly rather silly policy of printing 50 hardcopies of each article it publishes that contains nomenclatural acts, rather than just printing copies on demand for anyone who wants them.

[There has also been some talk on the list about whether this book counts as published under Article 8.6, “Works produced after 1999 by a method that does not employ printing on paper”, but there’s no room for debate about that.  That Article states that such a work “must contain a statement that copies (in the form in which it is published) have been deposited in at least 5 major publicly accessible libraries which are identified by name in the work itself”, which is not the case for this book.]

So what?

But the real question is: so what?  The Commission will never produce a ruling on this — it just doesn’t do that, unless presented with a formal petition to conserve a subsequently published name for the same taxon.  So in practice, whatever the code says, the reality is that the validity of the name Kayentavenator elysiae will — like the validity of all other names — be determined by whether and how it actually gets used in subsequent work.

In short, it comes down to this: when the next paper comes out on that animal, will it use Gay’s name, or will the worker in question erect his own name for the same animal and claim that it has priority as the first validly published name?

And that in turn comes down to — let’s be frank — the personality of that next worker.  We all know of scientists whose goal seems to be to get their name on as many publications and taxa as possible; we all know others who are more concerned with giving credit where it’s due.  It seems strange that something like the effective validity of a zoological name should be determined by a personality, but that’s how it looks.

As a side-issue, the way I read this is that Gay has done himself a huge disfavour by charging a fee to download the PDF version of his book.  If he wants his work to be accepted, then the best way is to make sure anyone who is remotely interested can get get hold of it with minimal inconvenience and at zero cost.  It may seem odd, but the truth is that Kayentavenator elysiae‘s chances of survival are dependent far more on marketing than on any other factor; so the PDFs should be made freely and easily available.

The sky is falling!  The sky is falling!

Tim Williams was one of several commenters on the DML to make this point:

This is a HUGE concern.  Especially because advances in technology mean that self-publication is now much cheaper than it used to be.  All you need is a computer and a printer, and off you go.

This has been true for some time. If anything, it’s surprising that we don’t see a lot more rogue taxonomy than we do, especially in a field as charismatic as dinosaur palaeontology. For some reason, extant animals seem (so far) to have suffered much more from this than we have — see for example Raymond Hoser, whose self-published taxonomic works have been widely referred to as “taxonomic vandalism” and whose name has been used in the term “Hoser taxonomy”.

I think we’re deluding ourselves if we think this isn’t coming to dinosaur palaeo.

The widely expressed fear is that “anyone, regardless of knowledge and abilities, will be able to create valid taxa without any restraints” (Dan Chure to the DML).  Because “when it comes to what constitutes a published work, Article 8 of the ICZN Code is so vague and permissive that it is laughably easy to meet the criteria” (Tim Williams again).

All true.

Unfortunately, it’s not a simple matter of tightening the language up. Even if the ICZN didn’t move so agonisingly slowly, it’s not really possible to give a rigorous definition of “valid publication”. You could come up with whatever form of words you wanted, and I (if I were sufficiently unethical) could find a way to make an end-run around it.

In particular, requiring peer-review (while a step in the right direction) would not solve the problem: then you have to define what “peer-review” means, and as we’ve seen in certain articles published in in-house journals in recent years, that concept is also slippery.

Here’s where I think this is going. Ultimately, the validity or otherwise of names is always decided by the working taxonomic (and more broadly biological) community. Until recently, the broader community has been able to delegate the process to journals in most cases, because it was easy to see what a “journal” was: it had a publisher, it was printed on glossy paper, and it came out on a regular schedule. It was easy to see whether a given work was in a journal or not.

That is changing very fast. By most of the criteria above, PLoS ONE is not a “journal” (no publisher but itself, no printing on paper, and no regular schedule) yet I don’t think anyone is going to claim it’s not a journal. Although I think PLoS ONE is a wonderful thing (I’ll be sending my own work there), one of its deleterious side-effects is that it, along with Palaeontologia Electronica and others, has shifted people’s ideas of what is “published”. One can easily imagine, say, a museum setting up its own PLoS-like journal — maybe a reputable one, maybe a less reputable one. From there it’s a short slide to a department, a small group or even an individual setting up his own journal. We have to face the facts that (A) it’s going to be hard to say what is and isn’t a “journal” and (B) we have no way of checking, in general, that “peer-review” is meaningful and adequate.

So I see only two possible paths.

One is that names will get published here, there and everywhere — ultimately even on blogs (although we don’t plan to go down that path here on SV-POW!) — and it will be up to the community to determine what is and isn’t counted as valid.

The other possibility is that a formal name-registration database like ZooBank comes swinging in to save the day, and only registered names are considered valid (or only registered names and those published before, say, 2012).

Unfortunately, ZooBank seems to be the only candidate registration system in town, and it’s in trouble: grotesquely underfunded, the work of basically one person, consequently well behind schedule and by no means ready technically or organisationally to do what it’s intended to do.  (I mean no criticism of any individual in saying this, but those are the facts.)

The way forward?

It seems that nomenclatural anarchy is inevitable unless something like ZooBank takes off rapidly.  So if I were rich and influential, one of the main things I’d be doing would be to pour that money and influence into ZooBank, getting it up to speed as soon as possible and making sure the infrastructure is in place to handle a lot of regsitrations really quickly.  Because the current de facto approach of delegating the assessment of legitimacy to journals is on the way out: I give it less than ten years.

But given that science is chronically underfunded, and zoology funded less than most sciences, and zoological nomenclature less than most of the rest of the zoology, I am not optimistic than this can be made to fly.  the bottom line for ZooBank is that it’s not anyone’s full-time or primary job; and until it is, there’s always going to be something else more urgent that pushes out this work that is merely important.  (Actually it’s urgent, too, but because the deadlines are soft rather than hard, the urgency isn’t apparent — we’ll just all wake up one day and find that they’ve passed.)

I’m not happy about it, but my prediction is: nomenclatural anarchy.  For sure, names published in JVP will start out with a better chance than names published in print-on-demand books at lulu.com, but that’s going to become a sliding scale rather than the clear black-and-white distinction we’ve been used to.

How bad is it?

I don’t know.  The truth is that lots of nomenclatural decisions are made by the community already, and somehow we all seem to survive.  I recently demonstrated, I thought conclusively, that the species formerly known as “Brachiosaurus” brancai cannot be considered congeneric with the Brachiosaurus type species B. altithorax, and must be considered to belong to its own genus Giraffatitan (Taylor 2009); but whether that reassignment is adopted is for the community to decide over the next few years.  I was disappointed to see that Chure et al. (2010), for poorly explained reasons, rejected this name; and I was pleased to see that Sander et al. (2010) accepted it.  But only time will tell whether it sticks.  And yet, somehow, we survive despite all this uncertainty.

Will it be so terrible if, in the same way, the published works of the community determine which nomenclatural acts are considered validly published?  Maybe not.

 

Third dorsal vertebra (FMNH PR 2209) of Rapetosaurus krausei in A, anterior view; B, posterior view; C, right lateral view. Abbreviations: acpl, anterior centroparapophyseal lamina; cprl, centroprezygapophyseal lamina; dp, diapophysis; pcdl, posterior centrodiapophyseal lamina; podl, postzygodiapophyseal lamina; posl, postspinal lamina; pozg, postzygapophysis; pp, parapophysis; ppdl, paradiapophyseal lamina; prdl, prezygodiapophyseal lamina; prpl, prezygoparapophyseal lamina; prsl, prespinal lamina; przg, prezygapophysis; spdl, spinodiapophyseal lamina. Scale bar equals 3 cm. (Curry Rogers 2009:fig. 16)

 

References

Posted by Mike Taylor
Filed in Nomenclature, open access, Rapetosaurus, Shiny digital future
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