The Astonishing Case of HMN SII:D8, part 3: Perforate Anterior Centroparapophyseal Laminae!

June 3, 2008

Welcome to the third and climactic episode in my HMN SII:D8 trilogy. If the unique spinoparapophyseal lamina and total lack of infradiapophyseal laminae featured in the first two episodes were not enough to creep you out, then this ought to do it: the ACPLs of this vertebra have great big holes in them!

Unfortunately, my photos of this are terrible. In some of my general shots of the vertebra, the perforations are visible if you already know what you’re looking for, but the only photos I have that really make the point are two where I shoved rolled-up pieces of paper through the holes. (NOTE TO HUMBOLDT CURATORS: I did this really, really carefully.) Those photos did not come out well (stupid autofocus), but here is one of the neural arch, taken from just below the level of the horizontal lamina complex, on the right-hand side:

D8 neural arch in right lateral view, showing perforate ACPL

The ACPLs of this vertebra are distinctly odd. Most ACPLs are fairly low, and directed straight out from the vertebra, in a lateral direction. These are way broader than your average ACPL in the street, and their orientation coming out of the vert is more anterolateral. Plus uh, they have these holes in them.

Are the holes damage? Nope. Sadly, I don’t have photos that demonstrate this, but as I recall from my visit, the holes are lined with finished bone. Plus the fact that the same morphology is seen on both sides makes that unlikely. I think they are a genuine osteological feature.

So what are we to make of all this? A single vertebra seems to have not one, not two but THREE osteological features not seen (or at least not recognised) in any other vertebra from any sauropod (including the other dorsals of the same specimen). What are the options?

1. This vertebra is damaged or diseased. I don’t think so: the fact that all three features (SPPLs, absence of IDLs and perforate ACDLs) are preserved on both sides makes this seem very unlikely.

2. Brachiosaurus brancai is much weirder than anyone, Janensch included, has given it credit for. I think that holds water if you buy the idea that the reason none of the other B.b dorsals have these features is poor preservation. I’ll need to look closely at the material in November. (I did look at it closely when I was there before, of course, but I didn’t know what I was doing back in my young-and-foolish days.)

3. This vertebra does not actually belong to Brachiosaurus brancai but to another animal. It’s an interesting possibility, and not one I would want to dismiss out of hand. Quarry S, whence HMN SII was excavated, contained at least two individuals which Janensch (1914) initially placed in two different species (B. brancai and B. fraasi) before changing his mind. What if he was right the first time round, and the “SII” specimen is a chimera? Unfortunately we’re not likely ever to know (unless new and better material is found) as Janensch’s quarry map as reproduced by Heinrich (1999) doesn’t give any clues. It is a mystery to both my family and the rest of the planet.

I wish I knew.

Well, that’s it from HMN SII:D8.  No doubt Matt will soon be back with some more blatant playing-to-the-gallery-posts comparing the sizes of whales and sauropods (I ask you, how off-topic is that?)  I know it’s been a bit hardcore, but, hey, that’s what we’re here for, right?

References

  • Heinrich, Wolf-Dieter. 1999. The taphonomy of dinosaurs from the Upper Jurassic of Tendaguru, Tanzania (East Africa), based on field sketches of the German Tendaguru expedition (1909-1913). Mitteilungen aus dem Museum fur Naturkunde in Berlin, Geowissenschaftliche Reihe, 2: 25-61.
  • Janensch, Werner. 1914. Ubersicht uber der Wirbeltierfauna der Tendaguru-Schichten nebst einer kurzen Charakterisierung der neu aufgefuhrten Arten von Sauropoden. Archiv fur Biontologie, Berlin, III, 1 (1): 81-110.
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12 Responses to “The Astonishing Case of HMN SII:D8, part 3: Perforate Anterior Centroparapophyseal Laminae!”

  1. Nathan Myers Says:

    As a member of “the gallery”, I would just like to mention that that rolled-up piece of paper sends me right to the moon.

  2. eotyrannus Says:

    Mike, I hope Daniel is listed as a coauthor on your work here [smiley].

  3. Matt Wedel Says:

    No doubt Matt will soon be back with some more blatant playing-to-the-gallery-posts comparing the sizes of whales and sauropods (I ask you, how off-topic is that?)

    You’re just jealous because of the record number of comments that post attracted.

    Those perforate lamina are seriously, seriously weird. Given how variable pneumatic morphology usually is, and given how asymmetric sauropod vertebrae often are, symmetrically perforate laminae strike me as substantially weirder than a one-off would have been.

    I nominate this vertebra for a new phylum.

  4. Mike from Ottawa Says:

    You’ll regret it later. Just ask Simon Conway Morris.

  5. Mike Taylor Says:

    Nailed, of course. Matt is right on target with his analysis of why I hate his super-popular whales-vs.-sauropods post. (Well. I love it, too, but this isn’t about that.)

    He’s also dead on in his suggestion that we remove HMN SII:D8 into its own phylum (or perhaps kingdom?). While we’re at it, maybe we should do the same for Xenoposeidon. I say we take off and reassign them from orbit. It’s the only way to be sure.

  6. Andreas Johansson Says:

    Why stop at kingdom? Superdomain!

  7. Nathan Myers Says:

    This is clearly a Godzilla vertebra. However, that makes it off-topic here.


  8. […] mentions in passing the spinoparapophyseal laminae, absence of an infradiapophyseal laminae and perforate anterior centroparapophyseal laminae of the 8th dorsal vertebra of the Brachiosaurus brancai specimen HMN SII — the features that […]


  9. […] this makes the perforate laminae in Giraffatitan all the […]


  10. […] But also like the median septa, the thin parts of the laminae are only rarely perforated (but it does happen), for possible (read: arm-wavy) reasons discussed in the recent FEA post. And maybe the amount of […]


  11. […] may be that I start talking about the perforated anterior centroparapophyseal laminae of Giraffatitan without having said what a centroparapophyseal lamina is.  I need another slide […]


  12. […] This photo was taken down in the basement of the Museum für Naturkunde Berlin, on the same 2008 trip where Matt took the “Mike in Love” photo from two days ago. For anyone who didn’t recognise the specific vertebra I was in love with in that picture, shame on you! It is of course our old friend the ?8th dorsal vertebra of the same specimen, which we’ve discussed in detail here on account of its unique spinoparapophyseal laminae, its unexpectedly missing infradiapophyseal lamina and its bizarre perforate anterior centroparapophyseal laminae. […]


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