My talk (Taylor and Wedel 2019) from this year’s SVPCA is up!

The talks were not recorded live (at least, if they were, it’s a closely guarded secret). But while it was fresh in my mind, I did a screencast of my own, and posted it on YouTube (CC By). I had to learn how to do this for my 1PVC presentation on vertebral orientation, and it’s surprisingly straightforward on a Mac, so I’ve struck while the iron is hot.

For the conference, I spoke very quickly and omitted some details to squeeze the talk into a 20-minute slot. In this version, I go a bit slower and make some effort to ensure it’s intelligible to an intelligent layman. That’s why it runs closer to half an hour. I hope you’ll find it worth your time.

References

An important paper is out today: Carpenter (2018) names Maraapunisaurus, a new genus to contain the species “Amphicoelias fragillimus, on the basis that it’s actually a rebbachisaurid rather than being closely related to the type species Amphicoelias altus.

Carpenter 2018: Figure 5. Comparison of the neural spine of Maraapunisaurus fragillimus restored as a rebbachisaurid (A), and the dorsal vertebrae of Rebbachisaurus garasbae (B), and Histriasaurus boscarollii (C). Increments on scale bars = 10 cm.

And it’s a compelling idea, as the illustration above shows. The specimen (AMNH FR 5777) has the distinctive dorsolaterally inclined lateral processes of a rebbachisaur, as implied by the inclined laminae meeting at the base of the SPOLs, and famously has the very excavated and highly laminar structure found in rebbachisaurs — hence the species name fragillimus.

Ken’s paper gives us more historical detail than we’ve ever had before on this enigmatic and controversial specimen, including extensive background to the excavations. The basics of that history will be familiar to long-time readers, but in a nutshell, E. D. Cope excavated the partial neural arch of single stupendous dorsal vertebra, very briefly described it and illustrated it (Cope 1878), and then … somehow lost it. No-one knows how or where it went missing, though Carpenter offers some informed speculation. Most likely, given the primitive stabilisation methods of the day, it simply crumbled to dust on the journey east.

Carpenter 2018: Frontispiece. E. D. Cope, the discoverer of AMNH FR 5777, drawn to scale with the specimen itself.

Cope himself referred the vertebra to his own existing sauropod genus Amphicoelias — basically because that was the only diplodocoid he’d named — and there it has stayed, more or less unchallenged ever since. Because everyone knows Amphicoelias (based on the type species A. altus) is sort of like Diplodocus(*), everyone who’s tried to reconstruct the size of the AMNH FR 5777 animal has done so by analogy with Diplodocus — including Carpenter himself in 2006, Woodruff and Foster (2014) and of course my own blog-post (Taylor 2010).

(*) Actually, it’s not; but that’s been conventional wisdom.

Ken argues, convincingly to my mind, that Woodruff and Foster (2014) were mistaken in attributing the great size of the specimen to a typo in Cope’s description, and that it really was as big as described. And he argues for a rebbachisaurid identity based on the fragility of the construction, the lamination of the neural spine, the extensive pneumaticity, the sheetlike SDL, the height of the postzygapophyses above the centrum, the dorsolateral orientation of the transverse processes, and other features of the laminae. Again, I find this persuasive (and said so in my peer-review of the manuscript).

Carpenter 2018: Figure 3. Drawing made by E.D. Cope of the holotype of Maraapunisaurus fragillimus (Cope, 1878f) with parts labeled. “Pneumatic chambers*” indicate the pneumatic cavities dorsolateral of the neural canal, a feature also seen in several rebbachisaurids. Terminology from Wilson (1999, 2011) and Wilson and others (2011).

If AMNH FR 5777 is indeed a rebbachisaur, then it can’t be a species of Amphicoelias, whose type species is not part of that clade. Accordingly, Ken gives it a new generic name in this paper, Maraapunisaurus, meaning “huge reptile” based on Maraapuni, the Southern Ute for “huge” — a name arrived at in consultation with the Southern Ute Cultural Department, Ignacio, Colorado.

How surprising is this?

On one level, not very: Amphicoelias is generally thought to be a basal diplodocoid, and Rebbachisauridae was the first major clade to diverge within Diplodocoidae. In fact, if Maraapunisaurus is basal within Rebbachisauridae, it may be only a few nodes away from where everyone previously assumed it sat.

On the other hand, a Morrison Formation rebbachisaurid would be a big deal for two reasons. First, because it would be the only known North American rebbachisaur — all the others we know are from South America, Africa and Europe. And second, because it would be, by some ten million years, the oldest known rebbachisaur — irritatingly, knocking out my own baby Xenoposeidon (Taylor 2018), but that can’t be helped.

Finally, what would this new identity mean for AMNH FR 5777’s size?

Carpenter 2018: Figure 7. Body comparisons of Maraapunisaurus as a 30.3-m-long rebbachisaurid (green) compared with previous version as a 58-m-long diplodocid (black). Lines within the silhouettes approximate the distal end of the diapophyses (i.e., top of the ribcage). Rebbachisaurid version based on Limaysaurus by Paul (2016), with outline of dorsal based on Rebbachisaurus; diplodocid version modified from Carpenter (2006).

Because dorsal vertebrae in rebbachisaurids are proportionally taller than in diplodocids, the length reconstructed from a given dorsal height is much less for rebbachisaurs: so much so that Ken brings in the new version, based on the well-represented rebbachisaur Limaysaurus tessonei, at a mere 30.3 m, only a little over half of the 58 m he previously calculated for a diplodocine version. That’s disappointing for those of us who like our sauropods stupidly huge. But the good news is, it makes virtually no difference to the height of the animal, which remains prodigious — 8 m at the hips, twice the height of a giraffe’s raised head. So not wholly contemptible.

Exciting times!

References

 

There’s a new paper out, describing the Argentinian titanosaur Mendozasaurus in detail (Gonzalez Riga et al. 2018): 46 pages of multi-view photos, tables of measurement, and careful, detailed description and discussion. But here’s what leapt out at me when I skimmed the paper:

Gonzalez Riga et al. (2018: figure 6). Mendozasaurus neguyelap cervical vertebra (IANIGLA-PV 076/1) in (A) anterior, (B) left lateral, (C) posterior, (D) right lateral, (E) ventral and (F) dorsal views. Scale bar = 150 mm. Sorry it’s monochrome, but that’s how it appears in the paper.

Just look at that thing. It’s ridiculous. In our 2013 PeerJ paper “Why Giraffes have Short Necks” (Taylor and Wedel 2013), we included a “freak gallery” as figure 7: five very different sauropod cervicals:

Taylor and Wedel (2013: figure 7). Disparity of sauropod cervical vertebrae. 1, Apatosaurus “laticollis” Marsh, 1879b holotype YPM 1861, cervical ?13, now referred to Apatosaurus ajax (see McIntosh, 1995), in posterior and left lateral views, after Ostrom & McIntosh (1966, plate 15); the portion reconstructed in plaster (Barbour, 1890, figure 1) is grayed out in posterior view; lateral view reconstructed after Apatosaurus louisae (Gilmore, 1936, plate XXIV). 2, “Brontosaurus excelsus” Marsh, 1879a holotype YPM 1980, cervical 8, now referred to Apatosaurus excelsus (see Riggs, 1903), in anterior and left lateral views, after Ostrom & McIntosh (1966, plate 12); lateral view reconstructed after Apatosaurus louisae (Gilmore, 1936, plate XXIV). 3, “Titanosaurus” colberti Jain & Bandyopadhyay, 1997 holotype ISIR 335/2, mid-cervical vertebra, now referred to Isisaurus (See Wilson & Upchurch, 2003), in posterior and left lateral views, after Jain & Bandyopadhyay (1997, figure 4). 4, “Brachiosaurus” brancai paralectotype MB.R.2181, cervical 8, now referred to Giraffatitan (see Taylor, 2009), in posterior and left lateral views, modified from Janensch (1950, figures 43–46). 5, Erketu ellisoni holotype IGM 100/1803, cervical 4 in anterior and left lateral views, modified from Ksepka & Norell (2006, figures 5a–d).

But this Mendozasaurus vertebra is crazier than any of them, with its tiny centrum, its huge, broad but anteroposteriorly flattened neural spine, and its pronounced lSPRLs.

I just don’t know what to make of this, and neither does Matt. And part of the reason for this may be that neither of us has had that much to do with titanosaurs. As Matt said in email, “Those weird ballooned-up neural spines in titanosaurs kind of freak me out.” And I could not agree more.

And of course as sauropodologists, we really should familiarise ourselves with titanosaurs. There are a lot of them, and they account for a lot of sauropod evolution. Someone recently made the point, either in an SV-POW! comment or on Facebook, that titanosaurs may be to sauropods what monkeys and apes are to primates: a subclade that is way more diverse than the rest of the clade put together.

It’s starting to look like an extreme historical accident that Camarasaurus, diplodocines and brachiosaurids — all temporally and/or geographically restricted groups — were the first well-known sauropods, and for decades defined our notion of what sauropods were like. Meanwhile, the much more widespread and long-surviving rebbachisaurs and titanosaurs were poorly understood until really the last 25 years or so. For the first century of sauropodology, our ideas about sauropods were driven by weird, comparatively short-lived outliers.

That our appreciation of titanosaur diversity has come so late says something about how our discovery of the natural world is more to do with geopolitics and the quirks of exploration than what’s actually out there. Sauropods were defined by diplodocids for so long because that’s what happened to be in the ground in the exposed rocks of North America, and that’s where the well-funded museums and expeditions were.

We at SV-POW! towers have often wondered how different our idea of what dinosaurs even were would be if the Liaoning deposits had been available to Buckland, Mantell, and Owen. It seems like that unavoidable that, if they’d first become familiar with feathered but osteologically aberrant (by modern standards) birds, one of two things would have happened. Either they would either have never coined the term “Dinosauria” at all, recognizing that Megalosaurus (and later Allosaurus and Tyrannosaurus) were just big versions of their little feathered ur-birds. Or they would have included Dinosauria as a primitive subclass of Aves.

References

  • González Riga, Bernardo J., Philip D. Mannion, Stephen F. Poropat, Leonardo D. Ortiz David and Juan Pedro Coria. 2018. Osteology of the Late Cretaceous Argentinean sauropod dinosaur Mendozasaurus neguyelap: implications for basal titanosaur relationships. Zoological Journal of the Linnean Society, 46 pages, 28 figures. doi:10.1093/zoolinnean/zlx103
  • Taylor, Michael P., and Mathew J. Wedel. 2013. Why sauropods had long necks; and why giraffes have short necks. PeerJ 1:e36. 41 pages, 11 figures, 3 tables. doi:10.7717/peerj.36

 


Note. This post contains material from all three of us (Darren included), harvested from an email conversation.

 

Today for the first time I saw Saegusa and Ikeda’s (2014) new monograph describing the Japanese titanosauriform Tambatitanis amicitiae. I’ve not yet had a chance to read the paper — well, it’s 65 pages long — but it certainly looks like they’ve done a nice, comprehensive job on a convincing new taxon represented by good material: teeth, braincase, dentary, atlas, and as-yet unprepared fragmentary cervical, fragmentary dorsals, sacral spines, some nice caudals, some ribs and chevrons, and pubis and ilium.

What catches the eye immediately is the bizarre forward-curved neural spines of the anterior caudals:

Saegusa and Ikeda (2104: fig. 8): Tambatitanis amicitiae gen. et sp. nov., holotype (MNHAH D-1029280). A, Cd2–Cd11 in right lateral view. B, Cdx1–Cdx2 in right lateral view.

Saegusa and Ikeda (2104: fig. 8): Tambatitanis amicitiae gen. et sp. nov., holotype (MNHAH D-1029280). A, Cd2–Cd11 in right lateral view. B, Cdx1–Cdx2 in right lateral view.

Here’s the third caudal in detail. (The first is fragmentary, and the second has some minor reconstruction near the tip of the spine which sceptical readers might think is covering up a misconstruction):

Saegusa and Ikeda (2014: fig. 11): Tambatitanis amicitiae gen. et sp. nov., holotype (MNHAH D-1029280). A–F, stereopairs of Cd3. A, right lateral view. B, left lateral view of the neural spine. C, anterior view. D, posterior view. E, dorsal view. F, ventral view. G, CT slices through the neural spine of Cd3, part corresponding to the matrix that filling the internal chamber is removed from the image. Greek letters in B and D indicate the position of CT slices shown in G. Scale bar = 10cm.

Saegusa and Ikeda (2014: fig. 11): Tambatitanis amicitiae gen. et sp. nov., holotype (MNHAH D-1029280). A–F, stereopairs of Cd3. A, right lateral view. B, left lateral view of the neural spine. C, anterior view. D, posterior view. E, dorsal view. F, ventral view. G, CT slices through the neural spine of Cd3, part corresponding to the matrix that filling the internal chamber is removed from the image. Greek letters in B and D indicate the position of CT slices shown in G. Scale bar = 10cm.

And here is the right-lateral view in close-up:

Saegusa and Ikeda (2014: fig. 11): Tambatitanis amicitiae gen. et sp. nov., holotype (MNHAH D-1029280) in right lateral view.

Saegusa and Ikeda (2014: fig. 11): Tambatitanis amicitiae gen. et sp. nov., holotype (MNHAH D-1029280) in right lateral view.

A phylogenetic analysis based on that of D’Emic (2012) recovers the new taxon in a polytomy with the Euhelopus clade that’s going to need a new name pretty soon, since it keeps growing and can’t be called Euhelopodidae for historical reasons: [that should probably be called Euhelopodidae: see discussion in comments]:

Saegusa and Ikeda (2014: fig. 23): Phylogenetic relationships of the titanosauriform sauropod Tambatitanis amicitiae gen. et sp. nov. from the Lower Cretaceous Sasayama Group of Tamba, Hyogo, Japan produced using the matrix of D'Emic (2012) with the addition of Tambatitanis. The final matrix, including 29 taxa and 119 characters, was analyzed in PAUP* 4.0b10. Left side, strict consensus of 81 most parsimonious trees (length = 207; CI = 0.609; RI = 0.8010; RC = 0.489), figures below nodes are decay indices. Right side, 50% majority rule consensus, figures above and below nodes represents the percentage of MPTs in which the node was recovered (only those relationships recovered in over 50% of the MPTs are shown).

Saegusa and Ikeda (2014: fig. 23): Phylogenetic relationships of the titanosauriform sauropod Tambatitanis amicitiae gen. et sp. nov. from the Lower Cretaceous Sasayama Group of Tamba, Hyogo, Japan produced using the matrix of D’Emic (2012) with the addition of Tambatitanis. The final matrix, including 29 taxa and 119 characters, was analyzed in PAUP* 4.0b10. Left side, strict consensus of 81 most parsimonious trees (length = 207; CI = 0.609; RI = 0.8010; RC = 0.489), figures below nodes are decay indices. Right side, 50% majority rule consensus, figures above and below nodes represents the percentage of MPTs in which the node was recovered (only those relationships recovered in over 50% of the MPTs are shown).

Nice to see that new sauropods just keep on rolling out of the ground faster than we can blog about them!

References

  • D’Emic, Michael D. 2012. The early evolution of titanosauriform sauropod dinosaurs. Zoological Journal of the Linnean Society 166:624-671.
  • Saegusa, Haruo, and Tadahiro Ikeda. 2014. A new titanosauriform sauropod (Dinosauria: Saurischia) from the Lower Cretaceous of Hyogo, Japan. Zootaxa 3848(1):1-66. doi:10.11646/zootaxa.3848.1.1

Emeus crassus mount

In a back room at the Field Museum, from my visit in 2012.

I took a lot of photos of the neck, which nicely records the transition in neural spine shape from simple to bifurcated–a topic of interest to sauropodophiles.

Emeus crassus neural spines

I think it’s fair to say that this “bifurcation heat-map”, from Wedel and Taylor (2013a: figure 9), has been one of the best-received illustrations that we’ve prepared:

Wedel and Taylor 2013 bifurcation Figure 9 - bifurcatogram

(See comments from Jaime and from Mark Robinson.)

Back when the paper came out, Matt rashly said “Stand by for a post by Mike explaining how it came it be” — a post which has not materialised. Until now!

This illustration was (apart from some minor tweaking) produced by a program that I wrote for that purpose, snappily named “vcd2svg“. That name is because it converts a vertebral column description (VCD) into a scalable vector graphics (SVG) file, which you can look at with a web-browser or load into an image editor for further processing.

The vertebral column description is in a format designed for this purpose, and I think it’s fairly intuitive. Here, for example, is the fragment describing the first three lines of the figure above:

Taxon: Apatosaurus louisae
Specimen: CM 3018
Data: —–YVVVVVVVVV|VVVuuunnn-

Taxon: Apatosaurus parvus
Specimen: UWGM 155556/CM 563
Data: –nnn-VVV—V-V|VVVu——

Taxon: Apatosaurus ajax
Specimen: NMST-PV 20375
Data: –n–VVVVVVVVVV|VVVVYunnnn

Basically, you draw little ASCII pictures of the vertebral column. Other directives in the file explain how to draw the various glyphs represented by (in this case) “Y”, “V”, “u”, and “n”.

It’s pretty flexible. We used the same program to generate the right-hand side (though not the phylogenetic tree) of Wedel and Taylor (2013b: figure 2):

Wedel and Taylor (2013b: Figure 2).

Wedel and Taylor (2013b: Figure 2).

The reason I mention this is because I released the software today under the GNU General Public Licence v3.0, which is kind of like CC By-SA. It’s free for anyone to download, use, modify and redistribute either verbatim or in modified form, subject only to attribution and the requirement that the same licence be used for modified versions.

vcd2svg is written in Perl, and implemented in part by the SVG::VCD module, which is included in the package. It’s available as a CPAN module and on GitHub. There’s documentation of the command-line vcd2svg program, and of the VCD file format. Also included in the distribution are two documented examples: the bifurcation heat-map and the caudal pneumaticity diagram.

Folks, please use it! And feel free to contribute, too: as the change-log notes, there’s work still to be done, and I’ll be happy to take pull requests from those of you who are programmers. And whether you’re a programmer or not, if you find a bug, or want a new feature, feel free to file an issue.

A final thought: in academia, you don’t really get credit for writing software. So to convert the work that went into this release into some kind of coin, I’ll probably have to write a short paper describing it, and let that stand as a proxy for the actual program. Hopefully people will cite that paper when they generate a figure using the software, the way we all reflexively cite Swofford every time we use PAUP*.

Update (12 April 2014)

On Vertebrat’s suggestion, I have renamed the program VertFigure.

References

Wedel and Taylor 2013 bifurcation Figure 4 - classes of bifurcation

Figure 4. Cervical vertebrae of Camarasaurus supremus AMNH 5761 cervical series 1 in anterior view, showing different degrees of bifurcation of the neural spine. Modified from Osborn & Mook (1921: plate 67).

Today sees the publication of my big paper with Mike on neural spine bifurcation, which has been in the works since last April. It’s a free download here, and as usual we put the hi-res figures and other supporting info on a sidebar page.

Navel-gazing about the publication process

This paper is a departure for us, for several reasons.

For one thing, it’s a beast: a little over 13,000 words, not counting tables, figure captions, and the bibliography. I was all geared up to talk about how it’s my longest paper after the second Sauroposeidon paper (Wedel et al. 2000), but that’s not true. It’s my longest paper, period (13192 vs 12526 words), and the one with the most figures (25 vs 22).

It’s the first time we’ve written the paper in the open, on the blog, and then repackaged it for submission to a journal. I have several things to say about that. First, it was more work than I expected. It turns out that I definitely do have at least two “voices” as a writer, and the informal voice I used for the initial run of blog posts (linked here) was not going to cut it for formal publication. So although there is very little new material in the paper that was not in the blog posts, a lot of the prose is new because I had to rewrite almost the whole thing.

I have mixed feelings about this. On one hand, last May kinda sucked, because just about every minute that wasn’t spent eclipse chasing was spent rewriting the paper. On the other hand, as Mike has repeatedly pointed out to me, it was a pretty fast way to generate a big paper quickly, even with the rewriting. It was just over two months from the first post in the destined-to-become-a-paper series on April 5, to submission on June 14 (not June 24 as it says on the last page of the PDF), and if you leave out the 10 days in late May that I was galavanting around Arizona, the actual time spent working on the paper was a bit under two months. It would be nice to be that productive all the time (it helped that we were basically mining everything from previously published work; truly novel work usually needs more time to get up and going).

Wedel and Taylor 2013 bifurcation Figure 18 - Barosaurus and Supersaurus cervicals

Figure 18. Middle cervical vertebrae of Barosaurus AMNH 6341 (top) and Supersaurus BYU 9024 (bottom) in left lateral view, scaled to the same centrum length. The actual centrum lengths are 850 mm and 1380 mm, respectively. BYU 9024 is the longest single vertebra of any known animal.

You may fairly wonder why, if almost all the content was already available on the blog, we went to the trouble of publishing it in a journal. Especially in light of sentiments like this. For my part, it’s down to two things. First, to paraphrase C.S. Lewis, what I wrote in that post was a yell, not a thought. I never intended to stop publishing in journals, I was just frustrated that traditional journals do so many stupid things that actually hurt science, like rejecting papers because of anticipated sexiness or for other BS reasons, not publishing peer reviews, etc. Happily, now there are better options.

Second, although in a sane world the quality of an argument or hypothesis would matter more than its mode of distribution, that’s not the world we live in. We’re happy enough to cite blog posts, etc. (they’re better than pers. comms., at least), but not everyone is, and the minimum bound of What Counts is controlled by people at the other end of the Overton window. So, bottom line, people are at least theoretically free to ignore stuff that is only published on blogs or other informal venues (DML, forums, etc.). If you want to force someone to engage with your ideas, you have to publish them in journals (for now). So we did.

Finally, ever since Darren’s azhdarchids-were-storks post got turned into a paper, it has bothered me that there is an icon for “Blogging on Peer-Reviewed Research” (from ResearchBlogging.org), but not one (that I know of) for “Blogging Into Peer-Reviewed Research”. If you have some graphic design chops and 10 minutes to kill, you could do the world a favor by creating one.

Hey, you! Want a project?

One of the few things in the paper that is not in any of the blog posts is the table summarizing the skeletal fusions in a bunch of famous sauropod specimens, to show how little consistency there is:

Wedel and Taylor 2013 NSB Table 1 - sauropod skeletal fusions

(Yes, we know that table legends typically go above, not below; this is just how they roll at PJVP.)

I want this to not get overlooked just because it’s in a long paper on neural spine bifurcation; as far as I’m concerned, it’s the most important part of the paper. I didn’t know that these potential ontogenetic indicators were all mutually contradictory across taxa before I started this project. Not only is the order of skeletal fusions inconsistent among taxa, but it might also be inconsistent among individuals or populations, or at least that’s what the variation among the different specimens of Apatosaurus suggests.

This problem cries out for more attention. As we say at the end of the paper:

To some extent the field of sauropod paleobiology suffers from ‘monograph tunnel vision’, in which our knowledge of most taxa is derived from a handful of specimens described decades ago (e.g. Diplodocus carnegii CM 84/94). Recent work by McIntosh (2005), Upchurch et al. (2005), and Harris (2006a, b, c, 2007) is a welcome antidote to this malady, but several of the taxa discussed herein are represented by many more specimens that have not been adequately described or assessed. A comprehensive program to document skeletal fusions and body size in all known specimens of, say, Camarasaurus, or Diplodocus, could be undertaken for relatively little cost (other than travel expenses, and even these could be offset through collaboration) and would add immeasurably to our knowledge of sauropod ontogeny.

So if you’re looking for a project on sauropod paleobiology and you can get around to a bunch of museums*, here’s work that needs doing. Also, you’ll probably make lots of other publishable observations along the way.

* The more the better, but for Morrison taxa I would say minimally: Yale, AMNH, Carnegie, Cleveland Museum of Natural History, Field Museum, Dinosaur National Monument, BYU, University of Utah, and University of Wyoming, plus Smithsonian, University of Kansas, OMNH, Denver Museum, Wyoming Dinosaur Center, and a few others if you can swing it. Oh, and Diplodocus hayi down in Houston. Check John Foster’s and Jack McIntosh’s publications for lists of specimens–there are a LOT more out there than most people are familiar with.

References