April 27, 2015
A couple of weekends ago, London and I went camping and stargazing at Afton Canyon, a nice dark spot about 40 miles east of Barstow. On the way home, we took the exit off I-15 at Ghost Town Road, initially because we wanted to visit the old Calico Ghost Town. But then we saw big metal dinosaurs south of the highway, and that’s how we came to Peggy Sue’s Diner and in particular the Diner-saur Park.
The Diner-saur Park is out behind the diner and admission is free. There are pools with red-eared sliders, paved walkways, grass, trees, a small gift shop, and dinosaurs. Here’s a Spinosaurus – curiously popular in the Mojave Desert, those spinosaurs.
Ornithischians are represented by two stegosaurs, this big metal one and a smaller concrete one under a tree.
The turtles are entertaining. They paddle around placidly and crawl out to bask on the banks of the pools, and on little islands in the centers.
The gift shop is tiny and the selection of paleo paraphernalia is not going to blow away any hard-core dinophiles. But it is not without its charm. And, hey, when you find a dinosaur gift shop in the middle of nowhere, you don’t quibble about size. London got some little plastic turtles and I got some cheap and horribly inaccurate plastic dinosaur skeletons to make a NecroDinoMechaLaser Squad for our Dinosaur Island D&D campaign.
Now, about that sauropod. The identification sign on the side of the gift shop notwithstanding, this is not a Brachiosaurus. With the short forelimbs and big back end, this is clearly a diplodocid. The neck is too skinny for Apatosaurus or the newly-resurrected Brontosaurus, and too long for Diplodocus. I lean toward Barosaurus, although I noticed in going back through these photos that with the mostly-straight, roughly-45-degree-angle neck, it is doing a good impression of the Supersaurus from my 2012 dinosaur nerve paper. Compare this:
If I had noticed it sooner, I would have maneuvered for a better, more comparable shot.
Guess I’ll just have to go back.
[Hi folks, Matt here. I’m just popping in to introduce this guest post by Adam Marsh (UT Austin page, LinkedIn, ResearchGate). Adam is a PhD student at UT Austin’s Jackson School of Geosciences, currently working for a semester as a Visiting Student Researcher at my old stomping ground, Berkeley’s UCMP. Adam’s been working at Petrified Forest National Park in the summers and most of his research is on the Navajo Nation in Arizona. His major interest is in how we perceive extinctions in the fossil record. Specifically, he’s exploring the geochronology of the Glen Canyon Group to look at the biotic response to the end-Triassic mass extinction. He’s also working on an overhaul of the early saurischian dinosaurs of western North America – hence this post. It’s timely because I was just talking in the last post about putting together infographics to spread your ideas; here Adam’s very nice diagram serves as a quick guide and pointer to several papers by Jeff Wilson and colleagues. Many thanks to Sarah Werning for suggesting that Adam and I get acquainted over vertebrae. Update the next day: both the diagram above and the PDF linked below have been updated to fix a couple of typos. Also, there are now black and white versions – see below.]
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If you’re like me, you don’t count sheep when you fall asleep, you count laminae. These struts of bone and their affiliated fossae connect and span between major structural features on vertebral neural arches such as prezygapophyses, postzygapophyses, parapophyses, diapophyses, hyposphenes, hypantra, and the neural spine. Presumably, laminae bracket and fossae house outgrowths of pneumatic diverticula from the respiratory system, which has been covered extensively on this blog in sauropodomorph dinosaurs.
Talking about these complicated structures is cumbersome; they’ve been called buttresses, ridges, struts, etc. throughout descriptive skeletal literature. But what we call things is important, especially when we introduce laminae and other vertebral structures to the rigors of phylogenetic systematics, where homologous apomorphies reign supreme. In order to avoid arguing about whether one structure is called the potato or the tomato, Jeff Wilson and others introduced a strategy of naming vertebral laminae (Wilson, 1999) and the fossae (Wilson et al., 2011) that they surround using the same vertebral landmarks that most tetrapod anatomists agree upon (see the parade of –apophyses above). The process is very simple. Vertebral laminae are named for the two structures that they connect; the prezygodiapophyseal lamina (prdl) connects the prezygapophysis and the diapophysis, so each neural arch will have two prdls. Vertebral fossae are named for the two major laminae that constrain them; the prezygocentrodiapophyseal fossa (prcdf) opens anterolaterally and is delineated dorsally by the prezygodiapophyseal lamina and ventrally by the anterior centrodiapophyseal lamina. Again, each neural arch will have two prcdfs. Those of you who are black belt vertebral anatomists, to borrow a favorite phrase from my advisor, might be interested in serial variation and how these structures change up and down the vertebral column. Until I get my act together and publish some cool new saurischian data, I will refer you to Wilson (2012). [We’ve also touched on serial variation in laminae in this post and this one. – MJW]
You might have noticed that the names are a mouthful and take up their fair share of typed characters. In my research of early saurischian dinosaurs, I’ve run across quite a few of these laminae everywhere from herrerasaurids to sauropodomorphs to coelophysoids to Dilophosaurus. Even though I’ve drawn, photographed, and written about various laminae and fossae, I still need to remind myself of what goes where and what it’s called. Believe me, vertebral lamina nomenclature does not lend itself well to Dem Bones covers. As a result, I’ve put together a reference figure that might be useful for those of you who are dealing with this or even teaching it to students. At the very least, you can put it on the ceiling above your bed so that it’s the first thing you see when you open your eyes in the morning.
Four main vertebral laminae are present plesiomorphically in archosaurs: the anterior and posterior centrodiapophyseal laminae, the prezygodiapophyseal lamina, and the postzygodiapophyseal lamina. This means that the prezygocentrodiapophyseal, postzygocentrodiapophyseal, and centrodiapophyseal fossae are present, and sometimes the top of the transverse process is concave between the neural spine and the zygapophyses to form the spinodiapophyseal fossa. I know that a certain sister group of Sauropodomorpha can get disparaged around these parts, but the truth is that theropods build long necks, too, and sometimes in very different ways than sauropodomorphs. When you are writing about the various vertebral buttresses and chonoses, don’t get frustrated with the names, because Wilson and his colleagues have actually made it much easier for us to talk to one another about presumably homologous structures without needing an additional degree in civil engineering.
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Here’s the figure again in PDF form: Marsh, Adam 2015 saurischian laminae and fossae diagram v2
And in black and white for those who prefer it that way: Marsh, Adam 2015 saurischian laminae and fossae diagram v2 bw
- Wilson, J. A. 1999. A nomenclature for vertebral laminae in sauropods and other saurischian dinosaurs. Journal of Vertebrate Paleontology 19(4): 639-653. DOI: 10.1080/02724634.1999.10011178
- Wilson, J. A., Michael, D. D., T. Ikejiri, E. M. Moacdieh, and J. A. Whitlock. 2011. A nomenclature for vertebral fossae in sauropods and other saurischian dinosaurs. PLoS One 6(2): e17114. DOI: 10.1371/journal.pone.0017114
- Wilson, J. A. 2012. New vertebral laminae and patterns of serial variation in vertebral laminae of sauropod dinosaurs. Contributions From The Museum of Paleontology, University of Michigan 32(7): 91-110. ISSN 0097-3556
February 2, 2015
Matt’s last post contained a nice overview of the occurrence of epipophyses in sauropodomorphs: that is, bony insertion points for epaxial ligaments and muscles above the postzygapophyseal facets. What we’ve not mentioned so far is that these structures are not limited to sauropods. Back when we were preparing one of the earlier drafts of the paper that eventually became Why sauropods had long necks; and why giraffes have short necks (Taylor and Wedel 2013a), I explored their occurrence in related groups. But that section never got written up for the manuscript, and now seems as good a time as any to fix that.
Theropods (including birds)
Most obviously, epipophyses occur in theropods, the sister group of sauropodomorphs.
In this figure from the 2013 paper, the rightmost images show cervical vertebrae of Majungasaurus (an abelisaurid theropod) and a turkey, both in posterior view. The red arrows indicate epaxial musculature pulling on the epipophyses. They are particularly prominent in Majungasaurus, rising almost a full centrum’s height above the postzygapophyseal facets.
The epipophyses are very prominent in the anterior cervicals of Tyrannosaurus, but much less so in its posterior cervicals — presumably because its flesh-tearing moves involved pulling upwards more strongly on the anterior part of the neck. Here’s a photo of the AMNH mount, from our post T. rex‘s neck is pathetic:
You can see something similar in the neck of Allosaurus, and the trend generally seems to be widespread among theropods.
Note the very prominent epipophyses protruding above the postzygs in the anterior cervicals of this Heterodontosaurus in the AMNH public gallery:
Here’s the hadrosaur Corythosaurus:
The prominent vertebra is C2: note that is has both a modest blade-like neural spine and prominent epipophyses — but that already by C3 the epipophyses are gone. Here is that C2 postzyg/epipophyses complex is close-up, clearly showing anteroposteriorly directed striations on the epipophysis, presumably representing the orientation of the attaching ligaments and muscles:
Here’s a close-up of the neck of the boring ornithopod Tenontosaurus, also in the AMNH gallery. (I’m not sure of the specimen number — if anyone can clarify, please leave a comment).
The interesting thing here is that it its axis (C2) seems to lack epipophyses (unlike C3), and to have a tall blade-like neural spine, as seen in mammals. We don’t really see C2 spines this big in other dinosaurs — compare with the much more modest spine in Corythosaurus, above. The texture of this part of the Tenontosaurus specimen looks suspicious, and I wonder whether that neural spine is a fabrication, created back in the day by AMNH staff who were so used to mammals that they “knew” what a C2 should look like? Anyway, the epipophysis above the postzyg of C3 is very distinct and definitely real bone.
Things get much more difficult with pterosaurs, because their cervicals are so fragile and easily crushed (like the rest of their skeleton, to be fair). While it’s easy to find nice, well-preserved ornithischian necks on display, you don’t ever really see anything similar for pterosaurs.
As a result, we have to rely on specimen photographs from collections, or more often on interpretive drawings. Even high-resolution photos, such as the one in Frey and Tischlinger (2012: fig 2) tend not to show the kind of detail we need. Usually, the only usable information comes from drawings made by people who have worked on the specimens.
Here, for example, is Rhamphorhynchus, well known as the most difficult pterosaur to spell, in figure 7 from Bonde and Christiansen’s (2003) paper on its axial pneumaticity:
It’s not the main point of the illustration, but you can make out clear epipophyses extending posteriorly past the postzygapophyseal facets in at least C3 and C5 — in C4, the relevant area is obscured by a rib. (Note that the vertebrae are upside down in this illustration, so you need to be looking towards the bottom of the picture.)
I’m pretty sure I’ve seen a better illustration of Rhamphorhynchus epipophyses, but as I get older my memory for Rhamphorhynchus epipophyses is no longer what it used to be and I can’t remember where. Can anyone help?
But also of interest is the azhdarchid pterosaur Phosphatodraco, here illustrated by Pereda Suberbiola et al. (2003):
The cervicals of Phosphatodraco seem to have no epipophyses. So they were not ubiquitous in pterosaurs.
What does it all mean? This post has become a bit of a monster already so I’ll save the conclusion for another time. Stay tuned for more hot epipophyseal action!
- Bonde, Niels and Per Christiansen. 2003. The detailed anatomy of Rhamphorhynchus: axial pneumaticity and its implications. pp 217-232 in: E. Buffetaut and J-M Mazin (eds), Evolution and Palaeobiology of Pterosaurs. Geological Society, London, Special Publications 217. doi:10.1144/GSL.SP.2003.217.01.13
- Frey Eberhard and Helmut Tischlinger. 2012. The Late Jurassic Pterosaur Rhamphorhynchus, a Frequent Victim of the Ganoid Fish Aspidorhynchus? PLoS ONE 7(3):e31945. doi:10.1371/journal.pone.0031945
- Janensch, Werner. 1950. Die Wirbelsaule von Brachiosaurus brancai. Palaeontographica, Supplement 7 3:27-93.
- O’Connor Patrick M. 2007. The postcranial axial skeleton of Majungasaurus crenatissimus (Theropoda: Abelisauridae) from the Late Cretaceous of Madagascar. pp 127-162 in: S. D. Sampson., D. W. Krause (eds), Majungasaurus crenatissimus (Theropoda: Abelisauridae) from the Late Cretaceous of Madagascar. Society of Vertebrate Paleontology Memoir 8.
- Osborn, Henry F., and Charles C. Mook. 1921. Camarasaurus, Amphicoelias and other sauropods of Cope. Memoirs of the American Museum of Natural History, New Series 3:247-387.
- Pereda Suberbiola, Xabier, Nathalie Bardet, Stéphane Jouve, Mohamed Iarochène, Baadi Bouya and Mbarek Amaghzaz. 2003. A new azhdarchid pterosaur from the Late Cretaceous phosphates of Morocco. pp 79-90 in: E. Buffetaut and J-M Mazin (eds), Evolution and Palaeobiology of Pterosaurs. Geological Society, London, Special Publications 217. doi:10.1144/GSL.SP.2003.217.01.08
- Taylor, Michael P., and Mathew J. Wedel. 2013. Why sauropods had long necks; and why giraffes have short necks. PeerJ 1:e36 doi:10.7717/peerj.36
November 21, 2014
…is not actually about scholarly publication. It’s Steve Albini’s keynote address at Melbourne’s Face the Music conference. It’s about the music industry, and how the internet transformed it from a restrictive, top-down oligarchy that mostly benefited middlemen into a more open, level, vibrant ecosystem where artists can get worldwide exposure for free, and yet are often compensated better than they were under the old system. Go read it, and then think about this:
Once the music world met the internet, the problem of getting information from musicians (authors) to listeners (readers) didn’t require any central planning to solve. What little building needed to happen was taken care of by people who were just happy to let the internet work the way it was designed to, and the way it works the most naturally: it makes sharing information almost effortless. Publishers (record labels) still exist, because they offer certain conveniences, but few people are under the delusion that they are necessary.
Over here in academia, we’ve already spent more than a decade wringing our hands over how to manage the shift from a barrier-based publishing world to one based on OA. We’ve put so much time and effort and thought into the problem of how to “save” or “transform” scholarly publishing. Why do we do that? Why not just walk away? Publishing is a button, and anything that we do to lend it any more importance–anything we feed it, in terms of time, effort, energy, or regard–is wasted. Wasted because we deliberately ignore the new reality in favor of propping up a system that performed a job that no-one needs done anymore. I keep wondering when the hell we’re all going to wake up, and start sharing our work the way that musicians and listeners share digital music.
And yet even out here on the crazy-eyed, axe-wielding fringe of the OA movement, we are still conservative. Zen Faulkes published a paper on his blog, and he did it 26 months ago, which is a near eternity in the Shiny Digital Future (it’s 13.4% of the lifespan to date of Google). Mike and I have admired that move, and talk about it, but we haven’t done it. Why not? We could even solicit peer reviews from people we know to be tough but fair reviewers. We all do unpaid editorial and review work for publishers, why not for each other directly? It’s like we’re thinking, “Okay, okay, I’ll review this paper, but only if there’s a publisher somewhere that will benefit from my unpaid labor!”
I suppose that for us, one answer is that PeerJ has given us other options that are just as easy as blogging, like posting preprints. So I am a bit torn: I like PeerJ, I support it, I have several papers in the pipeline that I’m planning on sending there. It offers certain conveniences, like sticking DOIs on everything for us, and tracking all of our metrics. But do we need PeerJ? I wonder if it is just the methadone that will help ease us out of our sad addiction to publishers.
Bonus observation: don’t just translate Albini’s thoughts on music to scholarly publishing, also try doing the reverse. It becomes pretty clear that the central theme of The Scholarly Kitchen is, “How will poor, helpless music listeners survive without all the middlemen to tell them what to listen to? They’ll be so lost.” Keep polishing that brass, guys, and thanks for the patronization!
The photos are of the dodo skeleton in the Yorkshire Museum, which I saw at SVPCA back in September. If you’re a dodo-phile like me, you should consider supporting Leon Claessens’s, Kenneth Rijsdijk’s, and Hanneke Meijer’s quest to better understand the skull and feeding mechanics of dodos. Their crowdfunding campaign runs through the end of the year–please go check it out.
November 3, 2014
Just a quick post to link to all five (so far) installments of the “necks lie” series. I need this because I want to cite all the “necks lie” posts in a paper that I’ll shortly submit, and it seems better to cite a single page than four of them.
- Necks lie
- Necks lie, redux
- Sauropods still didn’t hold their necks in osteological neutral pose
- Hoatzins lie (and so do parrots)
- Herons lie (and so do shoebills)
I’ll update this post as and when we write more about lying necks.
September 16, 2014
In the last post I pointed out some similarities between Davide Bonadonna’s new Spinosaurus painting and Brian Engh’s Spinosaurus painting from 2010. I also suggested that Davide might have borrowed from Brian and might have crossed a line in doing so. I was mistaken about that, as this post will show, and I’m sorry.
I woke up this morning to find that Mike and Davide had a very fruitful and collegial discussion going in email, which they had kindly copied me on. Davide had offered to send his in-progress sketches, Mike had offered to put them up here as a guest post, “because it’ll be a fascinating post — NOT as any kind of defense” (his words, with which I fully agree), and Davide had kindly assented (Brian’s post on how his Spinosaurus came to be is on his own blog). Davide and I corresponded directly this morning and he’s been very gracious and generous with his time, thoughts, and art.
We are always thrilled when we have the opportunity to show how awesome paleoart came into being (like this and this), and this case is no exception. Best now if I just get out of the way, so — over to Davide!
About the illustration:
In early November 2013, I was commissioned by NGMag, via Nizar Ibrahim of the University of Chicago, to create an illustration for a page in the October 2014 issue.
Working for about six years with Simone Maganuco, co-author of the study, on the Spinosaurus (I made the digital model from which the model exhibited in Washington was printed, Nizar left us carte blanche.
Some key points were essential, however: showing the Spinosaurus while swimming, his webbed feet, show its prey in the environment of Kemkem, possibly including all the major players in the scene, Mawsonia, Alanqa and Carcharodontosaurus.
Problems: the Spinosaurus is very long, the subjects to be represented too many. It was decided first of all to exclude the Carcharodontosaurus and then framing a foreshortened Spinosaurus, which would allow us to make room for the actors. Given the size and shape of Spinosaurus we knew that we would inevitably get what I call the “Luis Rey-effect” style. So, after gathering plenty of references, I made my sketches, suggesting a frontal dynamic sight (4) and a back view (1-2-3), presenting both solutions to Nizar at last SVP in L.A.
Meanwhile the size of the final art had to be changed because from the mag they asked for a double opening page of the article. And in the same time, thanks to a friend suggestion, I drew a third version (5), with the Idea to put all them together (8).
But the scene was too crowded and we decided to use just two animals, so I tried different combinations (6).
And the best one was to put both frontal versions together, one close to the other (7).
And again the two-pages image had to be changed because NG decided to turn it in a three-pages wide illustration, something that helped me to put Mawsonia in the background (9).
When finished, before approval, the NG editorial staff asked me to put an animal familiar to the modern public, which could help the reader to feel how big was the Spinosaurus, and a turtle was the chosen one (10).
Brian Engh’s illustration:
I vaguely remember I once had seen Brian’s illustration before today and I did not put it in my archive as a reference. All my main references are these: crocodile photos, patchworks made with my 3D digital model and Dinoraul one (11).
The water view comes from an NG poster about marine reptiles (12).
Most of my illustrations have a fisheye distortion, this is not the first one I make (see on my website Scipionyx, Neptunidraco, Diplodocus–Allosaurus and others).
You can easily see from the sketches progress how a traditional vanishing point becomes gradually a curve.
This is a case of illustrative convergence. ;-)
That’s all folks, I think. If you have any other doubt, just ask. I’m at your disposal.
September 15, 2014
UPDATE the next day: Since I published this post, it’s become clear that the similarities in the two images are in fact convergence. Davide Bonadonna got in touch with Mike and me, and he has been very gracious and conciliatory. In fact, he volunteered to let us post the making-of images for his painting, which I will do shortly. I’m sorry that my initial post was more inquisitorial than inquisitive, and implied wrongdoing on Davide’s part. Rather than edit it out of existence, I’m going to let it stand as a cautionary signal to my future self. Stand by for the new post as soon as I can get it assembled and published….aaaand here it is.
Scott Hartman has already explained—twice–that the super-short-legged, “Ambulocetus-grade” Spinosaurus from the new Ibrahim et al. (2014) paper has some major problems. Those are both good, careful, thought-provoking posts and you should go read them.
I’m writing about something else fishy with the “new” Spinosaurus and, in particular, National Geographic’s media push. Let’s check out this life restoration, newly prepared for the Spinosaurus story:
And now let’s look at this one by Brian Engh from a couple of years ago, borrowed from Brian’s art page:
And let’s count up the similarities:
- Two spinosaurs, one in the foreground with its head mostly or entirely submerged as it bites a fish, and one further back on the right with its head complete out of the water;
- Two turtles, one in the foreground with its head out of the water, and one further back on the right fully submerged;
- A good diversity of fish swimming around in the foreground;
- Pterosaurs flying way back in the background;
And finally, and most interestingly to me:
- A curved-water-surface, fish-eye perspective to the whole scene.
All the bits are moved around a bit, but pretty much everything in Brian’s picture is in the new one. Is it all just a big coincidence–or rather, a fairly lengthy series of coincidences? Seems unlikely. Your thoughts are welcome.