What’s the deal with your wacky postparapophyses, Shunosaurus?

March 8, 2010

Shunosaurus lii is a basal eusauropod from the Middle Jurassic of China.  Outside of palaeontological circles, it’s not at all well known — which is kind of surprising, as it’s one of the best represented of all sauropods.  It’s known from numerous complete skeletons, including skulls, and has been described in detail in Zhang’s (1988) monograph: 89 pages and 15 plates.  Here’s a skeleton of one individual, as found in the ground:

Shunosaurus lii, referred adult individual ZDM T5402, skeleton as found. From Zhang (1988:fig. 2)

Apart from being so well represented, Shunosaurus is known mostly for its tail club, which at the time of its discovery was unique among sauropods.  Despite recent discoveries of Mamenchisaurus hochuanensis individuals with preserved tail-clubs, and of Spinophorosaurus, the Shunosaurus tail-club is the best developed and best preserved.

But I don’t want to show you that.  I want to show you something I’ve been wanting to see for many years, and today finally saw for the first time: a feature of the dorsal vertebrae totally unique to Shunosaurus, known as postparapophyses.

Shunosaurus lii, referred juvenile individual ZDM T5401, dorsal vertebrae 3, 7 and 11 in left lateral view. Note postparapophyses on dorsals 7 and 11. From Zhang (1988:figs. 31-32)

Sadly, these are the only figures in the paper that show the postparapophyses (and as far as I know the only published figures anywhere).  So we have them in lateral view only, and lack what would be an informative posterior view.  Plate 10, part 1, supposedly shows one of the posterior dorsals in posterior view, but in my PDF at least the reproduction is so poor as to be wholly uninformative.

What makes things even worse is that the extended English-language abstract on pages 86-91 of Zhang (1988) does not mention this feature at all — in fact it occurs only in the list of anatomical abbreviations on page 6.  So, to the best of my knowledge, here is the entirety of what has been published in the English language about this feature based on observation of the material:

ppp, postparapophysis

Wilson and Sereno (1998:14-15) expanded a little on this, but it’s not clear that what they wrote was based on anything more than the figure above.  Here it is anyway, for completeness:

Comments–Zhang’s (1988:78-79) diagnosis listed numerous features, only a few of which appear to be autapomorphies of Shunosaurus lii.  One of the more striking autapomorphies is an unusual articulation between the ribs and the posterior dorsal vertebrae.  The parapophyseal articulation is split between adjacent vertebrae, with a portion of the articulation in its usual position by the prezygapophyses and an anterior extension located near the postzygapophysis on the preceding vertebra (Zhang, 1988:figs. 31, 32; “postparapophysis”).

That’s your lot.

So if we’re to make anything at all of the PPPs, it will have to be on the basis of the figure reproduced above.  And I don’t really know how much we can say.  The PPPs look sort of like postzygapophyses, havng a distinct ventrally oriented facet.  This makes me wonder whether they are in fact lateral extensions of the postzygapohyseal facets, perhaps connected by a lamina that would be visible in posterior view.

The bottom line is, I don’t know, and I would greatly appreciate comments (or better still, photos!) from anyone who has seen the material first-hand.

I leave you with Zheng’s (1988:fig. 57) skeletal reconstruction of this distinctively dumpy-looking sauropod.  Note by the way that the plantigrade manus reconstruction is almost certainly wrong: the metacarpals should be held in a more or less vertical arcade as in other sauropods.

Shunosaurus lii, referred adult individual ZDM T5402, skeletal reconstruction in left lateral view. From Zheng (1988:fig. 7). Man, that thing is ugly.

References

  • Wilson, Jeffrey A. and Paul C. Sereno.  1998.  Early evolution and Higher-level phylogeny of sauropod dinosaurs.  Society of Vertebrate Paleontology, Memoir 5: 1-68.
  • Zhang Yihong.  1988.  The Middle Jurassic dinosaur fauna from Dashanpu, Zigong, Sichuam, vol. 1: sauropod dinosaur (I): Shunosaurus. Sichuan Publishing House of Science and Technology, Chengdu, China.

Update (9 March 2010)

Rob Taylor found this nice photograph of what is apparently a skeletal mount of Shunosaurus: the original is here.  Any information about this mount will be gratefully received: please comment below if you know anything.

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20 Responses to “What’s the deal with your wacky postparapophyses, Shunosaurus?”

  1. Natalia Says:

    hey which dinosaur breed were in huge no. b4 there debacle?


  2. Since the parapophyses are the articulating surface of the lower branch of the dorsal thoracic ribs, maybe these postparapophyses (if they are even related to the parapophyses) indicate a unique articulation for the thoracic ribs, possibly swept strongly backwards?

  3. Nathan Myers Says:

    It’s bad enough to be extinct, but dumpy too? Proper manus reconstruction would make it just a little less dumpy.

  4. William Miller Says:

    Cool.

    I wonder why they have not really been published on … lack of sauropod workers compared to the number of fossils? material hard to access?

  5. Nathan Myers Says:

    Update: That is one big scapula. Or something.

  6. Rob Taylor Says:

    The image of the Shunosaurus skeletal mount turned out to be one of a series of construction pix that can be seen at the Finnish Museum of Natural History web site:

    http://www.fmnh.helsinki.fi/info/media/kuvia/ajankohtaiset/Shuno/index.htm

    If you run the introductory text through Google Translate, you get the following: “Shunosaurus lii dinosaur skeleton was erected in the museum of Natural History of Life Hall. Skeleton is a copy of the original fossil, which is preserved in a scientific museum in Beijing.”

  7. Jaime A. Headden Says:

    Xenarthrans have similar rigidifying articulations in the vertebrae, although the ribs are not incorporated, by extension of the processes overlying the adjacent verebrae (anteriorly and posteriorly), essentially locking the dorsal column together (it’s still capable of a minor amount of movement). Along with hyposphene/hypantral articulations, flattened central faces without anterior concavity (which if present would imply a bulbous intervertebral disk), various sauropods appear to be locking the dorsal column.

    I’ll go out on a limb and say that they may make taxa with such articulations less likely to “rear” than others.

  8. one layman Says:

    it is strange that the “skeleton as found” image seems to illustrate a complete skull, yet no trace of those HUGE teeth

  9. Niko Says:

    All I know about the mount is that it’s a copy in the Finnish Museum of Natural History in Helsinki. I’ve seen it a few times when I visited the Museum, but I didn’t remember it’s a Shunosaurus. Then again, I’m not an expert, so I wouldn’t know about these things…

    More pictures of the contruction and some info on the specimen:

    http://www.fmnh.helsinki.fi/verkkonayttelyt/dinosaurukset/s00.htm

    They say it’s a copy of a young individual. It was ordered from Beijing Museum of Natural History and it arrived in August 2000 in three boxes weighing totally 400 kg. There’s more information about the mountingprocess, but I’ll skip that now. Ask if you want to know what they say.

    A picture of the whole exhibition piece:

    http://www.fmnh.helsinki.fi/ltm/pysyvat/elamanhistoria.htm

    Two briefingings for the media are also available in Finnish (no pics), but I don’t have the time now to translate anything (suffice to say, there’s not much “hard” information in them, just good stories for the papers):

    http://www.fmnh.helsinki.fi/tiedotteet/?p=148

    http://www.fmnh.helsinki.fi/tiedotteet/?p=151

  10. John Conway Says:

    The toes are in reverse order in the skeletal. How on earth do these mistakes get made, and remain uncorrected?

  11. Mike Taylor Says:

    Wow, John, I can’t believe I missed that! Well spotted.


  12. Jaime:

    Mallison 2009 suggested the opposite, that more flexibility in the vertebral column, as apparently in some titanosaurs, made the animals less suited to rearing than those with less flexible backs. So maybe Shunosaurus was more specialized for tripodal rearing?

  13. Nima Says:

    Whoa that ugly skeletal evokes images of a bygone era… like perhaps the 1890s or something to that effect, back when Cope was still alive. And it’s actually from the 1980s???? Even ignoring the horrible posing, the bones don’t even look like they were drawn professionally. It seems China has a bit of catching up to do in paleontology… even today tail-dragging restorations by scientists are not uncommon there.

    The mounted skeleton looks a lot nicer, but I didn’t know the teeth were so insanely long. Was this in the original fossils?

  14. Niko Says:

    At least on the museums’ page they say that the teeth have fallen out of their sockets and that’s why they look so long on the mount. Does this then mean that they were not really “insanely long”?

  15. Nima Says:

    From looking just at that photo, it seems the teeth in the upper jaw are FAR too long, and not only that, they look fake. Just big rods of plaster. No spoon-shaped expansion at the end. They’re of uniform thickness all the way along the shaft. The lower teeth are fine though, they may be the real teeth.

    I have a big copy of Greg Paul’s skeletal of Shunosaurus, the upper teeth are much shorter in that one so I assume the skull he based it on had pretty normal-length teeth, and they do not all point straight DOWN at a precise 90 degrees like the skull in the photo (that would defeat the purpose of the upturned maxilla that was so characteristic of cetiosaurs!)

  16. Mike Taylor Says:

    Yes, those wacky teeth are fakezilla.

  17. brian engh Says:

    So I know this post ISN’T about the tail club, but 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?

  18. Mike Taylor Says:

    biran enhg, I’ll do a separate post on Shunosaurus tail clubs so I can show you pictures.


  19. [...] 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” [...]


  20. [...] reference 26 is Zhang (1988), which, embarrassingly, we’ve featured here on SV-POW! in our first Shunosaurus post.  Evidently I was so focussed on preparapophyses when I looked at that monograph [...]


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