Ending on a high note

December 31, 2012

Dicraeosaurus by Brian Engh

We’ve gotten a few complaints this year about how much time we’ve spent talking about open access instead of dinosaurs. Brian Engh is in the more-dinosaurs faction, but he doesn’t just whinge about our non-dino coverage, he does something about it. He writes:

here’s the deal:

when sv-pow becomes more discussion about human things and less discussion about ancient monsters i bombard your email with whatever crappy unfinished dino-drawings i got lying around. you have my permission to do with these as you wish, however if they end up on SV-POW i will be happy and feel i’m doing my part to combat humans.

Awesome.

Happy new year, sauropod fans. Enjoy this rearing Dicraeosaurus courtesy of Brian.

Best. Exhibit. Ever.

December 13, 2011

Wedel lab group photo, December 12, 2011. Vanessa Graff and Mathew Wedel, with Diplodocus carnegii, Giraffatitan brancai, Dicraeosaurus hansemanni and assorted stinkin’ theropods and ornithischians for scale.

A new perspective, or the same old thing?

A new perspective, or the same old thing?

Brachiosaurus and friends from here (hat tip to Ville Sinkkonen).

In an e-mail with explicit permission to quote, our colleague Casey Holliday sent the following thoughts about our new paper and the subsequent ten days of related blogging:

I don’t know guys. I like your blogs, and your papers are fine. And I liked this paper. And I’m a fan.  But it looks to me that you blogged about far more data, in- or not in support of your paper than you actually presented in your paper. So,…wtf? The posts on Dinomorph far exceeded your (or any) published rebuke. Your explanation (and honorable erred parts) of the semicircular canal data also exceeded that actual published part too, with extra photos, description etc. (is that error going to be OA published too?) Also additional pix of necks (e.g., Nigersaurus), and not only from sauropods that would have
potentially bettered the original pub. So what’s fair? Why weren’t
these data also included in the publication? Maybe it’s not my business and was taken up in review…I don’t know. Frankly, none of this blog stuff really counts in the peer-reviewed world of “real” publications. Its not like this blogging and comments all count as Supplementary Data either. But also, I’m obviously here commenting on it, so also crossing into the fray…But who really cares about all this discussion? Its no different than the DML or any other noise in the internet world (or is it). Similar to what Paul Barrett was posting on Tet Zoo…what counts? Why take up arguments here, when they should (maybe?likely?) be taken up more formally and privately.

If you’re going to air all this additional data and unreviewed
opinion, then I think this discussion is important.

I think this phenomenon of the sauropod neck paper is really
interesting. We have 3 scientists that published a paper, and then, thanks to their current blogosphere cred, basically unleashed a hype not seen in this way previously that I can remember. Maybe that’s the interesting part? and kudos. But interestingly…we’re seeing this intersection of traditional publication (OA or not), blogosphere description, and perhaps, almost certainly, excellent self-promotion.

I’m still a fan. I think this paper is generally solid. But I’m
particularly interested in this phenomenon and hope this is a fair
place to raise it.

The comment field is open, and we SV-POW!sketeers are going to refrain from commenting for a couple of days to let the conversation develop unfettered.

We are genuinely curious to know what you think.

In view of all the awesome that is the Humboldt Museum’s gigantic brachiosaur mount, it’s too easy to overlook another nearly-complete Tendaguru sauropod, mounted in the very same hall, that is also worthy of respect and, yes, awe.  Ladies and gentlemen, I give you: Dicraeosaurus hansemanni!

 

Dicraeosaurus mount, Humboldt Museum. Anterolateral view

Dicraeosaurus hansemanni mounted skeleton, Humboldt Museum, Berlin. Anterolateral view. Matt Wedel for scale.

 

Dicraeosaurus is a member of Dicraeosauridae, the family that, together with Diplodocidae makes up the whip-tailed clade Flagellicaudata; which in turn, with rebbachisaurids and a few bits and pieces, makes up the great neosauropod clade Diplodocoidea.  Dicraeosaurus was first named and briefly described by Janensch (1914:83); typically, Janensch went on to make full and detailed descriptions of its osteology, and also to describe the mounted skeleton (Janensch 1936).

It’s not really apparent from the photo above, but Dicraeosaurus is really small — like, embarrassingly small.  Especially when it’s standing next to Brachiosaurus brancai.  Gunga et al. (1999) estimated its mass at 12810 kg, but since that was the same paper that estimated B. b. at 74420 kg, based on a similarly grotesque baloon model, we can probably assume an accurate mass would be about one third of that, or 4000-5000 kg.  Smaller than a big elephant.  (I don’t know of any other published mass estimates for Dicraeosaurus; if I’ve missed any, please shout.)  This is typical for dicraeosaurs: the South American Amargasaurus and Brachytrachelopan are even smaller.

Dicraeosaurs are interesting for several reasons.  One is the dwarfism, and attendant shortening of the neck (which is taken to the extreme by Brachytrachelopan: reconstructed, that baby looks more like an ornithopod).  But maybe most interesting is the peculiar construction of the vertebrae, which have very tall neural spines:

 

Dicraeosaurus neck. Left lateral view.

Dicraeosaurus neck. Left lateral view.

 

Check this out.  The spines of C2-4 slope backwards; that of C5 is upright; from C6 onwards, they slope forwards.  Very strange.  Oh, and this is real: the verts are in good shape, and definitely not distorted.

One thing that Matt and I have been working on recently is the mechanics of sauropod necks, and particularly the attachment points of the epaxial ligaments and muscles.  Among diplodocids and other sauropods with bifid neural spines, you occasionally find a nice clear ligament attachment knob in the floor of the trough between the metapophyses (i.e. the paired neural-spine halves) — but the Humboldt Dicraeosaurus mount is the first specimen I’ve ever seen that has such a knob at the base of every single cervical’s metapophyseal trough.  See for yourself:

 

Ligament attachment knobs in intermetapophyseal trough of Dicraeosaurus neck. Posterodorsal view.

Ligament attachment knobs in intermetapophyseal trough of Dicraeosaurus neck. Posterodorsal view.

 

Unfortunately, as I was taking this last photo, and others like it, I came in a bit too close to the neck and touched one of the left cervical ribs (around C5).  Aaaand off it came, to shatter on the hard flooring.  It was a horrible moment … especially as I did it right in front of the curator, noted dicraeosaur lover Daniela Schwarz-Wings.  With his usual impeccable tact, Matt took the opportunity of snapping a photo of me showing her the pieces, and trying to show how two of them fit together.  Two more fragments lie on the floor at her feet:

 

Me apologising to Daniela for breaking a Dicraeosaurus cervical rib

Me apologising to Daniela for breaking a Dicraeosaurus cervical rib

 

Happily, the museum’s crack conservation unit swung into action immediately — I mean, literally within an hour — and I believe that rib is now back in place and as good as new.  Frightening.

The tall, bifid neural spines of dicraeosaurs continue into the dorsal sequence, resulting in a “tall back” that carries through the sacrum and into the anterior part of the tail — as the posterolateral view below sort of shows.  Just as the dicraeosaurid neck-shortening trend is taken to its extreme by Brachytrachelopan, so the elongation of neural spines reaches its apotheosis in Amargasaurus, which we must remember to show you one of these days.

 

A farewell to Dicraeosaurus. Right posterolateral view.

A farewell to Dicraeosaurus. Right posterolateral view. Also in view: the stinkin' stegosaur Kentrosaurus (left), Diplodocus (nearly obscured by Dicraeosaurus) and Brachiosaurus brancai (right and, er, top).

 

Update (22 December)

David Hone, of Archosaur Musings fame, has sent me this photograph of the Dicraeosaurus mount in the process of being put together by the good people at RCI.

 

RCI building the Humboldt Dicraeosaurus mount.

RCI building the Humboldt Dicraeosaurus mount.

 

References

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), pp. 81-110.

Janensch, W. 1936. Ein aufgestelltes Skelett von Dicraeosaurus hansemanni. Palaeontographica (suppl. 7), 299–308.