Rabbit skulls strike back: Kraatz and Sherratt (2016)
September 22, 2016
Facial tilt in extant leporids is strongly correlated with locomotor mode – fast movers have more strongly tilted faces. There’s a lot of homoplasy, which is to be expected with characters that are strongly driven by current function. Kraatz and Sherratt (2016: fig. 5).
Judgmental readers will recall that I have dabbled in mammal skulls, thanks to the corrupting influence of my friend and colleague, Brian Kraatz. At the end of my last post on this sordid topic, I mentioned that Brian and Emma Sherratt were working on a version 2.0 based in 3D morphometrics. The first volley from that project was published today in PeerJ.
Happily for all of us, Brian and Em confirmed the relationship between facial tilt and locomotor mode that we first documented last year, using more taxa, more landmarks, and two more dimensions (Kraatz and Sherratt 2016: 12):
…in accordance with previous findings by Kraatz et al. (2015), facial tilt angle is correlated with locomotor mode (D-PGLS, F(2,17) = 11.13, P = 0.003), where lower facial tilt angle, meaning more pronounced cranial flexion, is found in cursorial species, and high angles are found in generalist species.
That’s just the most personally relevant tip of a very large, multifaceted iceberg, including a monster supplementary info package on FigShare with, among other things, 3D models of bunny skulls. It’s all free and awesome, so go have fun.
That homoplastic pattern shown in figure 5, above? It’s been going on for a while. I’m gonna go out on a limb and guess that Hypolagus was a rocket. Kraatz and Sherratt (2016: fig. 7).
References
Should we still give taxonomic authorities?
September 18, 2016
I have before me the reviews for a submission of mine, and the handling editor has provided an additional stipulation:
Authority and date should be provided for each species-level taxon at first mention. Please ensure that the nominal authority is also included in the reference list.
In other words, the first time I mention Diplodocus, I should say “Diplodocus Marsh 1878″; and I should add the corresponding reference to my bibliography.
Marsh (1878: plate VIII in part). The only illustration of Diplodocus material in the paper that named the genus.
What do we think about this?
I used to do this religiously in my early papers, just because it was the done thing. But then I started to think about it. To my mind, it used to make a certain amount of sense 30 years ago. But surely in 2016, if anyone wants to know about the taxonomic history of Diplodocus, they’re going to go straight to Wikipedia?
I’m also not sure what the value is in providing the minimal taxonomic-authority information rather then, say, morphological information. Anyone who wants to know what Diplodocus is would be much better to go to Hatcher 1901, so wouldn’t we serve readers better if we referred to “Diplodocus (Hatcher 1901)”
Now that I come to think of it, I included “Giving the taxonomic authority after first use of each formal name” in my list of
Idiot things that we we do in our papers out of sheer habit three and a half years ago.
Should I just shrug and do this pointless busywork to satisfy the handling editor? Or should I simply refuse to waste my time adding information that will be of no use to anyone?
References
- Hatcher, Jonathan B. 1901. Diplodocus (Marsh): its osteology, taxonomy and probable habits, with a restoration of the skeleton. Memoirs of the Carnegie Museum 1:1-63 and plates I-XIII.
- Marsh, O. C. 1878. Principal characters of American Jurassic dinosaurs, Part I. American Journal of Science, series 3 16:411-416.
How horrifying was the neck of Barosaurus?
September 16, 2016
Suppose that I and Matt were right in our SVPCA talk this year, and the
“Supersaurus” cervical BYU 9024 really is the C9 of a gigantic Barosaurus. As we noted in our abstract, its total length of 1370 mm is exactly twice that of the C9 in AMNH 6341, which suggests its neck was twice as long over all — not 8.5 m but 17 m.
How horrifying is that?
I realised one good way to picture it is next to the entire mounted skeleton of Giraffatitan at the Museum für Naturkunde Berlin. That skeleton is 13.27 m tall. At 17 m, the giant barosaur neck would be 28% longer than the total height of Giraffatitan.
Giraffatitan brancai mounted skeleton MB.R.2181 at the Museum für Naturkunde Berlin, with neck of Barosaurus ?lentus BYU 9024 at the same scale. Photo by Axel Mauruszat, from Wikipedia; drawing from Scott Hartman’s Supersaurus skeleton reconstruction.
Yes, this looks ridiculous. But it’s what the numbers tell us. Measure the skeleton’s height and the neck length off the image yourself if you don’t believe me.
(Note, too, that the size of the C9 in that big neck is about right, compared with a previous scaled image that Matt prepared, showing the “Supersaurus” vertebra in isolation alongside the Chicago Brachiosaurus.)
Our Barosaurus preprint has risen from the grave!
September 14, 2016
Long-time SV-POW! readers will remember that three years ago, full of enthusiasm after speaking about Barosaurus at the Edinburgh SVPCA, Matt and I got that talk written up in double-quick time and had it published as a PeerJ Preprint in less than three weeks. Very quickly, the preprint attracted substantive, helpful reviews: three within the first 24 hours, and several more in the next few days.
This was great: it gave us the opportunity to handle those review comments and get the manuscript turned around into an already-reviewed formal journal submission in less then a month from the original talk.
So of course what we did instead was: nothing. For three years.
I can’t excuse that. I can’t even explain it. It’s not as though we’ve spent those three years churning out a torrent of other awesome papers. We’ve both just been … a bit lame.
Anyway, here’s a story that will be hauntingly familiar. A month ago, full of enthusiasm after speaking about Barosaurus at the Liverpool SVPCA, Matt and I found ourselves keen to write up that talk in double-quick time. It’s an exciting tale of new specimens, reinterpretation of an important old specimen, and a neck eight times as long as that 0f a world-record giraffe.
But it would be crazy to write the new Barosaurus paper without first having dealt with the old Barosaurus paper. So now, finally, three years on, we’ve done that. Version 2 of the preprint is now available (Taylor and Wedel 2016), incorporating all the fine suggestions of the people who reviewed the first version — and with a slightly spiffed-up title. What’s more, the new version has also been submitted for formal peer-review. (In retrospect, I can’t think why we didn’t do that when we put the first preprint up.)
Taylor and Wedel 2016: Figure 3. Barosaurus lentus holotype YPM 429, vertebra R, C?15. Top row: dorsal view; middle row: posterior, right lateral and anterior views; bottom row: ventral view, from Lull (1919: plate II). Note the apparently very low, undivided neural spine at the intersection of the SPRLs and SPOLs, forward-shifted neural arch, broad prezygapophyses, broad, wing-like prezygadiapophyseal laminae, and great width across the diapophyses and across the parapophyses. Abbreviations: dia, diapophysis; para, parapophysis; prz, prezygapophysis; prdl, prezygadiapophyseal lamina; spol, spinopostzygapophyseal lamina; sprl, spinoprezygapophyseal lamina. Scale bar = 500 mm.
A big part of the purpose of this post is to thank Emanuel Tschopp, Mark Robinson, Andy Farke, John Foster and Mickey Mortimer for their reviews back in 2013. I know it’s overdue, but they are at least all acknowledged in the new version of the manuscript.
Now we cross our fingers, and hope that the formally solicited reviews for the new version of the manuscript are as helpful and constructive as the reviews in that first round. Once those reviews are in, we should be able to move quickly and painlessly to a formally published version of this paper. (I know, I know — I shouldn’t offer such a hostage to fortune.)
Meanwhile, I will finally be working on handling the reviews of this other PeerJ submission, which I received back in October last year. Yes, I have been lax; but I am back in the saddle now.
References
- Taylor, Michael P., and Mathew J. Wedel. 2016. The neck of Barosaurus: longer, wider and weirder than those of Diplodocus and other diplodocines. PeerJ PrePrints 1:e67v2 doi:10.7287/peerj.preprints.67v2
What is the nature and purpose of a type specimen?
September 13, 2016
It’s been interesting seeing the response to my comment on the ICZN petition to establish Diplodocus carnegii as the replacement type species of the genus Diplodocus. In particular, Mickey Mortimer’s opposition to the petition seems to be based primarily on this argument:
The dinosaur community has recently lost sight of the fact that the type concept was never meant to indicate the most well preserved or described specimen/species.
I find this unconvincing, on the basis that the ICZN was never designed with dinosaurs in mind in the first place. For the great majority of the species that have been named under its rules, the selection of the obvious holotype has been perfectly adequate, because extant animals — by far the majority — are nearly all represented by complete and well-preserved specimens.
Alphina nigrosignata (type specimen; photo courtesy Geert Goemans, Department of Ecology and Evolutionary Biology, The University of Connecticut; specimen loaned from Herbert Zettel from The Museum of Natural History Vienna (NHMV). From University of Delaware, College of Agriculture & Natural Resources.
Dinosaurs — which in many cases are represented by eroded and distorted fossils of a tiny part of the animal — are already an aberration from the perspective of the ICZN, and that is why they sometimes need special treatment.
What are type specimens for, after all? The Code itself says “The fixation of the name-bearing type of a nominal taxon provides the objective standard of reference for the application of the name it bears” (Article 61.1); and comments that type specimens “are the international standards of reference that provide objectivity in zoological nomenclature” (Article 72.10). That is a role that YPM 1920 is simply not capable of fulfilling — and, more to the point, a role that it is not filling. The Diplodocus carnegii holotype CM 84 is the international standard of reference that provides objectivity in Diplodocus nomenclature. Slavishly following the usual provisions of the Code to retain the fiction that YPM 1920 fulfils this role simply does not reflect reality.
Some people occasionally object to the nomination of neotype specimens or replacement type species on the grounds that the Code does not require this. Of course it doesn’t: if it did, there would be no need for petitions. The fact that the Code allows for petitions constitutes explicit recognition that its usual provisions do not always suffice to produce the “sense and stability for animal names” that the Commission’s web-site used to have as its banner before the last redesign. Petitions exist precisely to allow the setting aside of the usual rules when sense and stability is served by doing do.
My comment in support of the Diplodocus carnegii ICZN petition
September 8, 2016
If you keep an eye on the wacky world of zoological nomenclature, you’ll know that earlier this year Emanuel Tschopp and Octávio Mateus published a petition to the International Commission on Zoological Nomemclature, asking them to establish Diplodocus carnegii, represented by the ubiquitous and nearly complete skeleton CM 84, as the type species of Diplodocus.
That is because Marsh’s (1878) type species, YPM 1920, is a pair of non-diagnostic mid-caudals which no-one has paid any attention to since 1901:
Tschopp and Mateus (2016: fig. 1). More anterior of the only two reasonably complete caudal vertebrae of the type specimen of Diplodocus longus (YPM 1920) in dorsal (A), anterior (B), left (C), posterior (D), right (E), and ventral (F) views. The neural spine is lost. The estimated position within the caudal column is caudal vertebra 17â24. Note the transverse ridge between the prezygapophyses shared with AMNH 223 (1).
I have now submitted a formal comment to the ICZN in support of the petition, in which I argue:
In its use as the definitive exemplar of the genus Diplodocus, as the foundation for numerous palaeobiological studies of the genus, and as the specifier for numerous important clades, the species D. carnegii is already effectively functioning as the type species of Diplodocus. Therefore the petition of Tschopp and Mateus (2016) requests only that the commission recognises de jure what is already the case de facto.
Anyone else who has strong feelings either in favour of or against the establishment of D. carnegii as a replacement type species for Diplodocus is welcome to submit their own comment to the ICZN. (I know of at least one person who has submitted a comment opposing the petition.)
The procedure is straightforward: just write your comment and email it to the Commision at iczn@nhm.ac.uk. (But it’s best also to copy your email to iczn@nus.edu.sg, as that seems to be where the ICZN is operating out of now: it took the NHM address four days to reply to my initial inquiry, but the Singaporean address responds quickly.)
References
- Marsh, O.C. 1878. Principal characters of American Jurassic dinosaurs, Part I. American Journal of Science (series 3) 16:411–416.
- Tschopp, Emanuel, and Octávio Mateus. 2016. Case 3700: Diplodocus Marsh, 1878 (Dinosauria, Sauropoda): proposed designation of D. carnegii Hatcher, 1901 as the type species. Bulletin of Zoological Nomenclature 73(1):17-24.
The Hallett and Wedel sauropod book is out now
September 2, 2016
I came home from SVPCA to find a heavy box waiting for me. It had my author’s copies of the book. I figured maybe they had gone out in advance of wide release, but nope, the book is shipping right now. This is welcome but unexpected. We only got the final files in a little over three months ago. I have no idea what alchemy the folks at Johns Hopkins University Press worked, to get the book out so fast, but I’m grateful.
We’ll have a book signing at SVP, at one in the LA area with both of us, and probably some local ones in Oregon and SoCal with just one author. I’ll announce those when we get them set up.
I have about a zillion people I need to thank, and I’ll probably do a FAQ about the book soon, but for now: it’s out. JHUP page. Amazon page.
Sauropod Vertebra Picture of the Week 