Hello, ladies!
March 28, 2019
To my shock, I find that we seem never to have posted Bob Nicholls’ beautiful sketch Hello, ladies! on SV-POW!. His recent tweet reminded me about this piece, so here it is!
Like so many classic sauropod sketches, this was executed during a mammal-tooth talk at SVPCA: this one back in 2013, the year of our first Barosarus talk. (Our second was in 2016.)
Bob’s sketch shows speculative sexual display behaviour. We have no direct evidence for (or against) such behaviour; but while we don’t believe sexual selection was the main reason for sauropods evolving long necks, it seems inevitable that long necks evolved for other purposes would be exapted for sexual display.
I always love Bob’s sketches — in fact, for most palaeoartists, I tend to like their sketches more than their finished pieces. Among the many things about this one that make me jealous is all the females in the background admiring the male: the economy of line where Bob can not only summon up a perfectly cromulent diplodocid head in a few strokes, but imbue it with a sense of being inquisitive about the display. It’s magical.
Whatever happened to that 2013 Barosaurus project?, you may ask.
Well, the first thing that happened is that after we submitted the abstract, entitled Barosaurus revisited: the concept of Barosaurus (Dinosauria: Sauropoda) is based on erroneously referred specimens, we realised that there was a tiny, tiny mistake in our work. So by the time I gave the talk at the actual conference, the title slide was this:
Then you will recall we did an efficient job of converting the conference presentation into a manuscript, which we submitted as a preprint less than a month after the conference. The preprint quickly garnered amazingly helpful comments, which we used to extensively revise the manuscript.
For reasons we don’t understand, there was a three-year delay before we got it submitted for peer-review in 2016; but when we did finally submit, we did it in the confident hope that it would sail through peer-review, having already been extensively reviewed and revised.
But it was not to be. When we got the reviews back, they asked for a ton of changes, and that process was just too dispiriting to face having already made a ton of changes based on the first set of comments just prior to the submission. So the tedious process got back-burnered, and the suddenly three more years passed.
The upshot is that I still need to handle the reviews on the 2nd version of the paper, and shove the blasted thing through the peer-review process. I will, to be frank, be glad to get it out of my POOP chute, so I can think about other things — not least, the 2016 Barosaurus project.
Neck ontogeny in Tyrannosaurus rex
March 14, 2019
Having spent much of the last few days playing with the cervical vertebrae of a subadult apatosaur, and trying to make sense of those of the mounted adult, neck ontogeny is much on our minds. Here’s an example from the less charismatic half of Saurischia.
I was forcibly struck, when seeing a cast of Jane the juvenile Tyrannosaurus in the museum gift-shop, by how weedy its neck is:
This being the Carnegie Museum, it was with us the work of a moment to scoot across to the Cretaceous gallery and compare with the neck of an adult, CM 9380:
As you can see, the transformation of the neck is every bit as dramatic as that of the skull, as a slender animal optimised for pursuit grows into a total freakin’ monster.
Someone ought to quantify this. I’m talking to you, theropod workers! (We’ll be busy over here with sauropods.)
Here are the full, uncropped and uncorrected, versions of the photos that I extracted the above from:
This is truly a magnificent museum.
Behold! The glory that is CM 555
March 12, 2019
Matt and I have completed Day 2 of our excursion to the Carnegie Musuem in Pittsburgh. Day 1 was spent in the public galleries, because collections aren’t open on Sunday, but today we got into the Big Bone room.
One of our targets was CM 555, a very nice nearly complete neck (C1-C14) from a subadult apatosaurine — quite possibly Brontosaurus excelsus, which is what John McIntosh catalogued it as, though I am not yet 100% convinced it’s the same thing as YPM 1980, the holotype of that species.
We were able to lay out the full sequence on the floor, on styroforam sheets, and spend quality time just looking at it and thinking about it. I don’t just mean documenting it for later analysis, but making use of that precious time right there with the physical specimen to think through together what it’s telling us. We have a bunch of new insights, which we’ll share when we’re not completely exhausted.
Here’s Matt with the first six cervicals. C1 (the atlas) is as usual an unprepossessing lump, but then things get interesting. C2 to C6 are all unfused, so the centra and neural arches are separate.
Behind C6, the arches are fused to the centra (though the fusion lines are still apparent in C7 and C8). This is a nice example of how, in sauropods, serial position recapitulates ontogeny — one of the great confounding factors when studying isolated vertebrae.
We’ve learned a lot already from CM 555. Tomorrow will be spent with the two big mounted diplodocids (Diplodocus carnegii CM 84 and Apatosaurus louisae CM 3018). We’ll let you know how it goes. I predict: awesome.
BRONTOSMASH! in a kids’ book
February 15, 2019
Thanks to a comment from long-time reader Andrew Stuck, I realised he is also the tweeter @dinodadreviews, who pointed us to Xenoposeidon in a kids’ book. Now, a review on his website of Ted Rechlin‘s comic-book Jurassic has pointed me to what I think is the first depiction of the BRONTOSMASH! hypothesis in a kids’ book:
This is nice work: it captures the mass of the animals, and resists the nearly ubiquitous tendency to make their necks too slender and elegant. The necks do look rather too short here, but I think we can explain that away as perspective foreshortening.
You’d have to say, though, that it owes more than a little inspiration to the third of Brian Engh’s early sketches:
I suppose there are only a certain number of ways to draw two apatosaurs fighting.
Anyway, it’s great to see what we consider a solidly supported palaeobiological hypothesis out there influencing young hearts and minds. We should also take this as a well-deserved prod to get on with the actual paper, which after all was meant to follow hard on the heels of our 2015 SVPCA presentation.
By the way, folks: the spelling and punctuation is “BRONTOSMASH!”. Not “Brontosmash”, not “BRONTOSMASH”: all in capitals, with an exclamation mark. It’s “the BRONTOSMASH! hypothesis”.
If you followed along with the last post in this series, you now have some bird vertebrae to play with. Here are some things to do with them.
1. Learn the parts of the vertebrae, and compare them with those of other animals
Why are we so excited about bird vertebrae around here? Mostly because birds are reasonably long-necked living dinosaurs, and although their vertebrae differ from those of sauropods in relative proportions, all of the same bits are present in roughly the same places. If you know the parts of a bird vertebra and what each one does, you have a solid foundation for inferring the functions of sauropod vertebrae. Here’s a diagram I made for my SVP poster with Kent Sanders way back in 1999. I used an ostrich vertebra here but you should be able to find the same features in a cervical vertebra of just about any bird.
These are both middle cervical vertebrae in right lateral view. A middle cervical vertebra of a big ostrich will be between 3 and 4 inches long (7.5-10 cm), and one from a big brachiosaur like Giraffatitan will be about ten times longer.
I should do a whole post on neck muscles, but for now see this post and this paper.
2. Put the vertebrae in order, and rearticulate them
It is often useful to know where you are in the neck, and the only way to figure that out is to determine the serial position of the vertebrae. Here’s an articulated cervical series of a turkey in left lateral view, from Harvey et al. (1968: pl. 65):
Harvey’s “dorsal spine” is the neural spine or spinous process, and his “ventral spine” is the carotid process. The “alar process” is a sort of bridge of bone connecting the pre- and postzygapophyses; you can see a complete version in C3 in the photo below, and a partial version in C4.
Speaking of that photo, here’s my best attempt at rearticulating the vertebrae from the smoked turkey neck I showed in the previous post, with all of the vertebrae in left dorsolateral view.
These things don’t come with labels and it can take a bit of trial and error to get them all correctly in line. C2 is easy, with its odd articular surface for the atlas and narrow centrum with a ventral keel. Past that, C3 and C4 are usually pretty blocky, the mid-cervicals are long and lean, and then the posterior cervicals really bulk out. Because this neck section had been cut before I got it, some of the vertebrae look a little weird. Somehow I’m missing the front half of C6. The back half of C14 is also gone, presumably still stuck to the bird it went with, and C7 and C12 are both sectioned (this will come in handy later). I’m not 100% certain that I have C9 and C10 in the right order. One handy rule: although the length and neural spine height change in different ways along the column, the vertebrae almost always get wider monotonically from front to back.
And here’s the duck cervical series, in right lateral view. You can see that although the specific form of each vertebra is different from the equivalent vert in a turkey, the same general rules apply regarding change along the column.
Pro tip: I said above that these things don’t come with labels, but you can fix that. Once you have the vertebrae in a satisfactory order, paint a little dot of white-out or gesso on each one, and use a fine-point Sharpie or art pen to write the serial position (bone is porous and the white foundation will keep the ink from possibly making a mess). You may also want to put the vertebrae on a string or a wire to keep them in the correct order, but even so, it’s useful to have the serial position written on each vertebra in case you need to unstring them later.
3. Look at the air spaces
One nice thing about birds is that all of the species that are readily commercially available have pneumatic traces on and in their vertebrae, which are broadly comparable to the pneumatic vertebrae of sauropods.
The dorsal vertebrae of birds are even more obviously similar to those of sauropods than are the cervicals. These dorsal vertebrae of a duck (in left lateral view) show a nice variety of pneumatic features: lateral fossae on the centrum (what in sauropods used to be called “pleurocoels”), both with and without foramina, and complexes of fossae and foramina on the neural arches. Several of the vertebrae have small foramina on the centra that I assume are neurovascular. One of the challenges in working with the skeletal material of small birds is that it becomes very difficult to distinguish small pneumatic foramina and spaces from vascular traces. Although these duck vertebrae have small foramina inside some of the lateral fossae, the centra are mostly filled with trabecular, marrow-filled bone. In this, they are pretty similar to the dorsal vertebrae of Haplocanthosaurus, which have fossae on the neural arches and the upper parts of the centra, but for which the ventral half of each centrum is a brick of non-pneumatic bone. For more on distinguishing pneumatic and vascular traces in vertebrae, see O’Connor (2006) and Wedel (2007).
This turkey cervical, in left posterolateral view, shows some pneumatic features to nice advantage. The lateral pneumatic foramina in bird cervicals are often tucked up inside the cervical rib loops where they can be hard to see and even harder to photograph, but this one is out in the open. Also, the cervicals of this particular turkey have a lot of foramina inside the neural canal. In life these foramina are associated with the supramedullary diverticula, a set of air-filled tubes that occupy part of the neural canal in many birds — see Atterholt and Wedel (2018) for more on this unusual anatomical system. The development of foramina inside the neural canal seems to be pretty variable among individuals. In ostriches I’ve seen individuals in which almost every cervical has foramina inside the canal, and many others with no foramina. For turkeys it’s even more lopsided in my experience; this is the first turkey in which I’ve found really clear pneumatic foramina inside the neural canals. This illustrates one of the most important aspects of pneumaticity: pneumatic foramina and cavities in bones show that air-filled diverticula were present, but the absence of those holes and spaces does not mean that diverticula were absent. Mike and I coined the term “cryptic diverticula” for those that leave no diagnostic traces on the skeleton — for more on that, see the discussion section in Wedel and Taylor (2013b).
Finally, it’s worth taking a look at the air spaces inside the vertebrae. Here’s a view into C12 of the turkey cervical series shown above. The saw cut that sectioned this neck happened to go through the front end of this vertebra, and with a little clean-up the honeycomb of internal spaces is beautifully displayed. If you are working with an intact vertebra, the easiest way to see this for yourself is to get some sandpaper and sand off the front end of the vertebra. It only takes a few minutes and you’ll be less likely to damage the vertebrae or your fingers than if you cut the vertebra with a saw. Similar complexes of small pneumatic cavities are present in the vertebrae of some derived diplodocoids, like Barosaurus (see the lateral view in the middle of this figure), and in most titanosauriforms (for example).
I have one more thing for you to look for in your bird vertebrae, and that will be the subject of the next installment in this series. Stay tuned!
References
- Atterholt, J., and Wedel, M. 2018. A CT-based survey of supramedullary diverticula in extant birds. 66th Symposium on Vertebrate Palaeontology and Comparative Anatomy, Programme and Abstracts, p. 30 / PeerJ Preprints 6:e27201v1
- Harvey, E.B., Kaiser, H.E. and Rosenberg, L., 1968. An atlas of the domestic turkey (Meleagris gallopavo). Myology and osteology. U.S. Atomic Energy Commission, Germantown, Maryland, 247 pp.
- O’Connor, P.M. 2006. Postcranial pneumaticity: an evaluation of soft-tissue influences on the postcranial skeleton and the reconstruction of pulmonary anatomy in archosaurs. Journal of Morphology 267:1199-1226.
- Wedel, M.J. 2007a. What pneumaticity tells us about ‘prosauropods’, and vice versa. Special Papers in Palaeontology 77:207-222.
- Wedel, Mathew J., and Michael P. Taylor. 2013. Caudal pneumaticity and pneumatic hiatuses in the sauropod dinosaurs Giraffatitan and Apatosaurus.PLOS ONE 8(10):e78213. 14 pages. doi:10.1371/journal.pone.0078213
We may never know how flexible sauropod necks were
November 8, 2018
The more I look at the problem of how flexible sauropod necks were, the more I think we’re going to struggle to ever know their range of motion It’s just too dependent on soft tissue that doesn’t fossilise. Consider for example the difference between horse necks (above) and camel necks (below).
The skeletons of both consist of vertebrae that are pronouncedly opisthocoelous (convex in front and concave behind), so you might think their necks would be similarly flexible.
But the balls of horse cevicals are deeply embedded in their corresponding sockets, while those of camels have so much cartilage around and between them that the tip of the ball doesn’t even reach the rim of the socket. As a result of this (and maybe other factors), camel necks are far more flexible than those of horses.
Which do sauropod necks resemble? We don’t currently know, and we may never know. It will help if someone gets a good handle on osteological correlates of intervertebral cartilage.
[This post is recycled and expanded from a comment that I left on a Tetrapod Zoology post, but since Tet Zoo ate that comment it’s just as well I kept a copy.]
Mike Taylor interview by Szymon Górnicki
October 18, 2018
A while back — near the start of the year, in fact — Szymon Górnicki interviewed me by email about palaeontology, alternative career paths, open access, palaeoart, PeerJ, scholarly infrastructure, the wonder of blogging, and how to get started learning about palaeo. He also illustrated it with this caricature of me, nicely illustrating our 2009 paper on neck posture.
For one reason and another, it’s taken a long while for me get around to linking to it — but here we are in October and I’ve finally arrived :-)
With apologies to Szymon for the delay: here is the interview!
By the way, Szymon’s also done interviews with other, more interesting people: Davide Bonadonna, Steve Brusatte, Tim Haines and Phil Currie. Check them out!
When is a vertebra “horizontal”, part 2
August 28, 2018
Thanks to everyone who’s engaged with yesterday’s apparently trivial question: what does it mean for a vertebra to be “horizontal”? I know Matt has plenty of thoughts to share on this, but before he does I want to clear up a couple of things.
This is not about life posture
First, and I really should have led with this: the present question has nothing to do with life posture. For example, Anna Krahl wrote on Twitter:
I personally find it more comprehensible if the measurements relate to something like eg. the body posture. This is due to my momentary biomech./functional work, where bone orientation somet is difficult to define.
I’m sympathetic to that, but we really need to avoid conflating two quite different issues here.
Taylor, Wedel and Naish (2009), Figure 1. Cape hare Lepus capensis RAM R2 in right lateral view, illustrating maximally extended pose and ONP: skull, cervical vertebrae 1-7 and dorsal vertebrae 1-2. Note the very weak dorsal deflection of the base of the neck in ONP, contrasting with the much stronger deflection illustrated in a live rabbit by Vidal et al. (1986: fig. 4). Scalebar 5 cm.
If there’s one thing we’ve learned in the last couple of decades, it’s that life posture for extinct animals is controversial — and that goes double for sauropod necks. Heck, even the neck posture of extant animals is terribly easy to misunderstand. We really can’t go changing what we mean by “horizontal” for a vertebra based on the currently prevalent hypothesis of habitual posture.
Also, note that the neck posture on the left of the image above is close to (but actually less extreme than) the habitual posture of rabbits and hares: and we certainly wouldn’t want to illustrate vertebrae as “horizontal” when they’re oriented directly upwards, or even slightly backwards!
Instead, we need to imagine the animal’s skeleton laid out with the whole vertebral column in a straight line — sort of like Ryder’s 1877 Camarasaurus, but with the tail also elevated to the same straight line.
Ryder’s 1877 reconstruction of Camarasaurus, the first ever made of any sauropod, modified from Osborn & Mook (1921, plate LXXXII).
Of course, life posture is more important, and more interesting, question than that of what constitutes “horizontal” for an individual vertebra — but it’s not the one we’re discussing right now.
In method C, both instances are identically oriented
I’m not sure how obvious this was, but I didn’t state it explicitly. In definition C (“same points at same height in consecutive vertebrae”), I wrote:
We use two identical instances of the vertebrae, articulate them together as well as we can, then so orient them that the two vertebrae are level
What I didn’t say is that the two identical instances of the vertebrae have to be identically oriented. Here’s why this is important. Consider that giraffe C7 that we looked at last time, with its keystoned centrum. if you just “articulate them together as well as we can” without that restriction, you end up with something like this:
Which is clearly no good: there’s no way to orient that such that for any given point on one instance, the corresponding point on the other is level with it. What you need instead is something like this:
In this version, I’ve done the best job I can of articulating the two instances in the same attitude, and arranged them such that they are level with each other — so that the attitude shown here is “horizontal” in sense C.
As it happens, this is also just about horizontal in sense B — the floor of the neural canal is presumably at the same height as the top of the centrum as it meets the neural arch.
But “horizontal” in sense A (posterior articular surface vertical) fails horribly for this vertebra:
To me, this image alone is solid evidence that Method A is just not good enough. Whatever we mean by “horizontal”, it’s not what this image shows.
References
- Osborn, Henry Fairfield, and Charles C. Mook. 1921. Camarasaurus, Amphicoelias and other sauropods of Cope. Memoirs of the American Museum of Natural History, n.s. 3:247-387, and plates LX-LXXXV.
- Taylor, Michael P., Mathew J. Wedel and Darren Naish. 2009. Head and neck posture in sauropod dinosaurs inferred from extant animals. Acta Palaeontologica Polonica 54(2):213-220.
- Vidal, Pierre Paul, Werner Graf and Alain Berthoz. 1986. The orientation of the cervical vertebral column in unrestrained awake animals. Experimental Brain Research 61:549-559.
Necks lie: solitaire edition
May 2, 2018
Here at SV-POW! we’re big fans of the way that animals’ neck skeletons are much more extended, and often much longer, than you would guess by looking at the complete animal, with its misleading envelope of flesh.
Here’s another fine example, from John Hutchinson’s new post A Museum Evolves:
Solitaire (flightless bird), skeleton and taxidermy at University Museum of Zoology at Cambridge (UMZC). Photo by John Hutchinson.
Looking at the stuffed bird, it seems that it could get by perfectly well with half as many cervical vertebra, if only it didn’t carry them in such a strange posture.
Well — I say strange. It seems inefficient, yet it must be doing something useful, because it’s essentially ubiquitous among birds and many mammals … including rabbits, as long-time readers will remember.
The “Growth series of one” poster is published
September 22, 2017
This was an interesting exercise. It was my first time generating a poster to be delivered at a conference since 2006. Scientific communication has evolved a lot in the intervening decade, which spans a full half of my research career to date. So I had a chance to take the principles that I say that I admire and try to put them into practice.
It helped that I wasn’t working alone. Jann and Brian both provided strong, simple images to help tell the story, and Mike and I were batting ideas back and forth, deciding on what we could safely leave out of our posters. Abstracts were the first to go, literature cited and acknowledgments were next. We both had the ambition of cutting the text down to just figure captions. Mike nailed that goal, but my poster ended up being slightly more narrative. I’m cool with that – it’s hardly text-heavy, especially compared with most of my efforts from back when. Check out the text-zilla I presented at SVP back in 2006, which is available on FigShare here. I am happier to see, looking back, that I’d done an almost purely image-and-caption poster, with no abstract and no lit cited, as early as 1999, with Kent Sanders as coauthor and primary art-generator – that one is also on FigShare.
I took 8.5×11 color printouts of both my poster and Mike’s, and we ended up passing out most of them to people as we had conversations about our work. That turned out to be extremely useful – I had a 30-minute conversation about my poster at a coffee break the day before the posters even went up, precisely because I had a copy of it to hand to someone else. Like Mike, I found that presenting a poster resulted in more and better conversations than giving a talk. And it was the most personally relaxing SVPCA I’ve ever been to, because I wasn’t staying up late every night finishing or practicing my talk.
I have a lot of stuff to say about the conference, the field trip, the citability of abstracts and posters (TL;DR: I’m for it), and so on, but unfortunately no time right now. I’m just popping in to get this posted while it’s still fresh. Like Mike’s poster, this one is now published alongside my team’s abstract on PeerJ PrePrints.
I will hopefully have much more to say about the content in the future. This is a project that Jann, Brian, and I first dreamed up over a decade ago, when we were grad students at Berkeley. Mike provided the impetus for us to get it moving again, and kindly stepped aside when I basically hijacked his related but somewhat different take on ontogeny and serial homology. When my fall teaching is over, I’m hoping that the four of us can take all of this, along with additional examples found by Mike that didn’t make it into this presentation, and shape it into a manuscript. I’ll keep you posted on that. In the meantime, the comment field is open. For some related, previously-published posts, see this one for the baby sauropod verts, this one for CM 555, and this one for Plateosaurus.
Flying over Baffin Island on the way home.
And finally, since I didn’t put them into the poster itself, below are the full bibliographic references. Although we didn’t mention it in the poster, the shell apex theory for inferring the larval habits of snails was first articulated by G. Thorson in 1950, which is referenced in full here.
Literature Cited
- Bair, A.R. 2007. A model of wear in curved mammal teeth: controls on occlusal morphology and the evolution of hypsodonty in lagomorphs. Paleobiology 33(1):53-75.
- Gilmore, C.W. 1936. Osteology of Apatosaurus with special reference to specimens in the Carnegie Museum. Memoirs of the Carnegie Museum 11: 175-300.
- Hatcher, J.B. 1901. Diplodocus (Marsh): its osteology, taxonomy, and probable habits, with a restoration of the skeleton. Memoirs of the Carnegie Museum 1:1-63.
- Kraatz, B.P., Meng, J., Weksler, M. and Li, C. 2010. Evolutionary patterns in the dentition of Duplicidentata (Mammalia) and a novel trend in the molarization of premolars. PloS one, 5(9), p.e12838.
- Sych, L. 1975. Lagomorpha from the Oligocene of Mongolia. Palaeontogia Polonica 33:183-200.
- Thorson, G. 1950. Reproductive and larval ecology of marine bottom invertebrates. Biological Reviews 25(1):1-45.
- Wedel, M.J., and Taylor, M.P. 2013. Neural spine bifurcation in sauropod dinosaurs of the Morrison Formation: ontogenetic and phylogenetic implications. Palarch’s Journal of Vertebrate Palaeontology 10(1):1-34. ISSN 1567-2158.
- Wedel, M.J., Cifelli, R.L., and Sanders, R.K. 2000b. Osteology, paleobiology, and relationships of the sauropod dinosaur Sauroposeidon. Acta Palaeontologica Polonica 45:343-388.
Sauropod Vertebra Picture of the Week 
