At last it can be told!
May 10, 2011
People who’ve been paying especially close attention may have noted than on four separate occasions in the last eighteen months, I’ve casually referred to our old buddy HMN SII as the paralectotype specimen of Giraffatitan brancai. (Butchering a wallaby, photographing big bones, How fat was Camarasaurus, and baby giraffe neck, in case you were wondering.)
Giraffatitan brancai paralectotype HMN SII in the justly underrated left posteroventrolateral view, slightly obscured by a bit of Boring Old Diplodocus neck
But in my Big Brachiosaur Bonanza (Taylor 2009:788), I nominated HMN SII as the lectotype of this species. So why all this paralectotype stuff? Well, what I wrote in the paper was:
The original type specimen, “Skelett S” (Janensch, 1914:86) was subsequently found (e.g., Janensch, 1929:8) to consist of two individuals, which were designated SI (the smaller) and SII (the larger and more complete). Janensch never explicitly designated these two specimens as a syntype series or nominated either specimen as a lectotype; I therefore propose HMN SII as the lectotype specimen of Brachiosaurus brancai.
But in May last year, I got an email from Mark Konings, a dinosaur enthusiast from the Netherlands, pointing out (more politely than I deserved) that I’d got this wrong. In fact, Janensch did nominate a lectotype — the wrong one, SI, but we’re stuck with it. He did this in a paper on skulls (Janensch 1935-1936:151), which is why I overlooked it. (Well, that and the fact that he rather inconsiderately wrote in German.)
Once I’d been shown my mistake, I realised that the only thing to do was formally correct it in JVP, where the original article had been, so I sent them the shortest and most boring manuscript I’ve ever written (and it is up against some pretty stiff competition in the “most boring” category). And that manuscript was published today (Taylor 2011), fixing my dumb mistake.
Many thanks to Mark for spotting this!
References
- Janensch, Werner. 1935-36. Die Schadel der Sauropoden Brachiosaurus, Barosaurus und Dicraeosaurus aus den Tendaguru-Schichten Deutsch-Ostafrikas. Palaeontographica 2 (Suppl. 7) 2:147-298.
- Taylor, Michael P. 2009. A re-evaluation of Brachiosaurus altithorax Riggs 1903 (Dinosauria, Sauropoda) and its generic separation from Giraffatitan brancai (Janensch 1914). Journal of Vertebrae Paleontology 29(3):787-806.
- Taylor, Michael P. 2011. Correction: a re-evaluation of Brachiosaurus altithorax Riggs 1903 (Dinosauria, Sauropoda) and its generic separation from Giraffatitan brancai (Janensch 1914). Journal of Vertebrae Paleontology 31(3):727.
Sauropod Vertebra Picture of the Week 
May 10, 2011 at 8:10 am
HA! I got you on that: my paper on how someone couldn’t read German and falsly defined a lectotype came out first :p
http://www.ingentaconnect.com/content/schweiz/njbgeol/2011/00000259/00000002/art00004
May 10, 2011 at 1:40 pm
You’re welcome :).
May 11, 2011 at 2:31 am
Interesting that the specimens got what seem to be more standardized numbers. Do you know if the rest of the Tendaguru material (like Elaphrosaurus) is now also HM.R.____?
May 11, 2011 at 6:10 am
I think all the Tendaguru material is being renumbered, but the process is not complete AFAIK. Daniela Schwarz-Wings would be the person to ask.
May 19, 2011 at 7:21 am
[…] bones. However, the real bones that they’re based on are those of two specimens — the lectotype SI and paralectotype SII. The former includes cervicals 2-7, and we can be confident about that because C2 in sauropods is […]
November 12, 2011 at 4:24 am
I have my suspicions (especially now after SVP) that HMN SI and SII are two different species or even different genera. They just look far too different to be the same animal. What we know as Giraffatitan (i.e. the Berlin mount) is mostly HMN SII, so I agree that it should have been the lectotype. Too bad Janensch lumped them together and designated the less complete SI as the lectotype… which means that HMN SII (and most of the referred Giraffatitan material) might have to be renamed… AGAIN…
November 12, 2011 at 10:21 am
Nima, on what are your suspicions based? Since SI is known only from some skull fragments and the first seven cervicals, and the overlapping elements are pretty much identical with those of SII, I’m rather at a loss to see what your basis could be. The closest thing to a reason for suspecting there are two different brachiosaurs in Quarry S is the section Association of the Giraffatitan Lectotype Material in Taylor 2009:800-801, but that is carefully phrased in very speculative terms. Do you have new data?
November 12, 2011 at 9:31 pm
@Nima and Mike: I too think that the cervicals preserved in MB.R.2180 (SI) are different proportionally than in MB.R.2181 (SII). It might be tempting to think they’re different taxa, Nima, but I got to agree with Mike that taxonomic separation is premature.
The reason I say this is that it is possible that some sauropods followed a trend of peramorphosis–that is, as they grew older they display unseen traits as in younger individuals (although the younger individuals may be sexually mature). This appears to be the case with Alamosaurus, for instance (see Woodward and Lehman, 2009). In fact, the series of nine Alamosaurus cervicals from Big Bend has now been prepared and displayed at the DMNS over the summer, and even though the neural spines and overall proportions are strikingly different compared to the juvenile, Thomas Lehman has said to me (in an email) that this specimen exhibits all the diagnostic morphologies (e.g., types of laminae, placement of laminae, etc.) of the juvenile specimen.
Considering the ontogeny of dinosaurs in general seems to be a lot more complex than traditionally assumed (see ceratopsian ontogeny and phylogeny, for example), I’d say it is hasty to try to split MB.R.2180 from MB.R.2181 when we know very little about how any sauropod matured.
Ref–
Woodward, H.N., and Lehman, T.M. 2009. Bone histology and microanatomy of Alamosaurus sanjuanensis (Sauropoda: Titanosauria) from the Maastrichtian of Big Bend National Park, Texas. Journal of Vertebrate Paleontology 29(3):807-821.
November 13, 2011 at 1:58 pm
The proportions are not the only odd thing about HMN SI. Also there’s the actual shape of the neural arches. Trace the curve and slope of the spinoprezygapophyseal laminae, and a funny trend emerges – those of HMN SI show more of a “step” incline relative to the smooth incline of HMN SII’s laminae. Also in SI the slope of the posterior centrodiapophyseal laminae as far more diagonal relative to the centrum, and their posterior ends are far thicker and deeper than in SII. And then there are the far shorter prezygapophyses andthe completely different arrangement of pneumatic fossae around the neural arch and parapophyses.
Now I’ll still leave open the possibility that SI could be a Giraffatitan, but it’s highly doubtful to me. The neck in SI is only marginally thinner but the vertebrae are far shorter relative to their height. So either Giraffatitan’s neck went through a crazy growth spurt before adulthood (HMN-SII sized individuals have unfused shoulder blades) and rearranged the fossae and changed the slope of all the spinoprezygapophyseal laminae, or SI is not a young Giraffatitan but some other animal entirely.
IMO it looks a lot like some of the Archbishop material in terms of vertebra shapes, proportions, and neural spine slope. But that’s just a quick guess.
January 16, 2013 at 10:14 am
[…] Ideal sauropod vertebra: it’s the eighth cervical of our old friend the Giraffatitan brancai paralectotype MB.R.2181. (previously known as “Brachiosaurus” brancai HM S II — yes, it’s […]
September 5, 2013 at 7:58 am
[…] down in the collections, where we were particularly pleased to see the much-admir’d C8 of Giraffatitan‘s paralectotype, MB.R.2181 (previously known as HMN […]
October 2, 2017 at 7:45 am
[…] the Giraffatitan brancai paralectotype MB.R.2181. Of course, back then, we thought it was the type (it’s not), it was thought to belong to Brachiosaurus brancai (mea culpa), and the specimen number was HMN […]