November 30, 2011
- Part 1: intro
- Part 2: the head
- Part 3: the neck
- Part 4: body, tail, limbs, base, and skull
- Part 6: texture and color
- Part 7: verdict
There are really only a couple of interesting points to discuss for posture: the neck and the feet.
The neck posture is fine. Easy to say, but since I’m one of the “sauropods held their necks erect” guys, it might need some unpacking.
On one hand, animals really do use stereotyped postures, especially for the neck and head (Vidal et al. 1986, Graf et al. 1995, van der Leeuw et al. 2001). The leading hypothesis about why animals do this is that the number of joints and muscle slips involved in the craniocervical system permits an almost limitless array of possible postures, and that having a handful of stereotyped postures cuts down on the amount of neural processing required to keep everything going. That doesn’t mean that animals only use stereotyped postures, just that they do so most of the time, when there’s no need to deviate.
This might work something like the central pattern generators in your nervous system. When you’re walking down the sidewalk thinking about other things or talking with a friend, a lot of the control of your walk cycle is handled by your spinal cord, not your brain. Your brain is providing a direction and a speed, but the individual muscles are being controlled from the spinal cord. Key quote from the Wikipedia article: “As early as 1911, it was recognized, by the experiments of T. Graham Brown, that the basic pattern of stepping can be produced by the spinal cord without the need of descending commands from the cortex.”
But then you see a puddle or some dog doo and have to place your foot just so, and your brain takes over for a bit to coordinate that complex, ad hoc action. After the special circumstance is past, you go back to thinking about whatever and your spinal cord is back in charge of putting one foot in front of the other. This is the biological basis of the proverbial chicken running around with its head cut off: thanks to the spinal cord, the chicken can still run, but without a brain it doesn’t have anywhere to go (I have witnessed this, by the way–one of the numerous benefits to the future biologist of growing up on a farm).
Similarly, if the craniocervical system has a handful of regular postures–alert, feeding, drinking, locomoting, and so on–it lightens the load on the brain, which doesn’t have to figure out how to fire every muscle slip inserting on every cervical vertebra and on the skull to orient the head just so in three-dimensional space. That doesn’t mean that the brain doesn’t occasionally step in and do that, just like it takes over for the spinal cord when you place your feet carefully. But it doesn’t have to do it all the time.
van der Leeuw et al. (2001) took this a step further and showed that birds not only hold their heads and necks in stereotyped postures, they move between stereotyped postures in very predictable ways, and those movement patterns differ among clades (fig. 7 from that paper is above). There is a lot of stuff worth thinking about in that paper, and I highly recommend it, along with Vidal et al. (1986) and Graf et al. (1995), to anyone who is interested in how animals hold their heads and necks, and why.
So, on one hand, its wrong to argue that stereotyped postures are meaningless. But it’s also wrong to infer that animals only use stereotyped postures–a point we were careful to make in Taylor et al. (2009). And it’s especially wrong to infer that paleoartists only show animals doing familiar, usual things–I wrote the last post partly so I could make that point in this one.
For example, I think it would be a mistake to look at Brian Engh’s inflatable Sauroposeidon duo and infer that he accepts a raised alert neck posture for sauropods. He might or might not–the point is that the sauropods in the picture aren’t doing alert, they’re doing “I’m going to make myself maximally impressive so I can save myself the wear and tear of kicking this guy’s arse”. The only way the posture part of that painting can be inaccurate is if you think Sauroposeidon was physically incapable of raising its neck that high, even briefly (the inflatable throat sacs and vibrant colors obviously involve another level of speculation).
Similarly, the Sideshow Apatosaurus has its neck in the near-horizontal pose that is more or less standard for depictions of diplodocids (at least prior to 2009, and not without periodic dissenters). But it doesn’t come with a certificate that says that it is in an alert posture or that it couldn’t raise its neck higher–and even if it did, we would be free to ignore it. Would it have been cool to see a more erect-necked apatosaur? Sure, but that’s not a new idea, either, and there are other restorations out there that do that, and in putting this apatosaur in any one particular pose the artists were forced to exclude an almost limitless array of alternatives, and they had to do something. (Also, more practically, a more erect neck would have meant a larger box and heftier shipping charges.)
So the neck posture is fine. Cool, even, in that the slight ribbing along the neck created by the big cervical ribs (previously discussed here) gives you a sense of how the posture is achieved. Visible anatomy is fun to look at, which I suspect is one of the drivers behind shrink-wrapped dinosaur syndrome–even though it’s usually incorrect, and this maquette doesn’t suffer from it anyway.
Next item: the famous–or perhaps infamous–flipped-back forefoot. I have no idea who first introduced this in skeletal reconstructions and life restorations of sauropods, but it was certainly popularized by Greg Paul. It’s a pretty straightforward idea: elephants do this, why not sauropods?
Turns out there are good reasons to suspect that sauropods couldn’t do this–and also good reasons to think that they could. This already got some air-time in the comments thread on the previous review post, and I’m going to start here by just copying and pasting the relevant bits from that discussion, so you can see four sauropod paleobiologists politely disagreeing about it. I interspersed the images where they’re appropriate, not because there were any in the original thread.
Mike Taylor: the GSP-compliant strong flexion of the wrist always look wrong to me. Yes, I know elephants do this — see Muybridge’s sequence [above] — but as John H. keeps reminding us all, sauropods were not elephants, and one might think that in a clade optimsied for size above all else, wrist flexibility would not be retained without a very good reason.
Adam Yates: Yes I agree with Mike here, the Paulian, elephant-mimicking hyperflexion of the wrist is something that bugs me. Sauropod wrist elements are rather simple flat structures that show no special adaptation to achieve this degree of flexion. [Lourina sauropod right manus below, borrowed from here.]
Heinrich Mallison: Hm, I am not too sure what I think of wrist flexion. Sure it looks odd, but if you think it through the very reasons elephant have it is likely true in sauropods. And given the huge amount of cartilage mossing on the bones AND the missing (thus shape unknown) carpals I can well imagine that sauropods were capable of large excursions in the wrist.
Mike: What are those reasons?
Heinrich: Mike, long humeri, very straight posture – try getting up from resting with weak flexion at the wrist. Or clearing an obstacle when walking. I can’t say too much, since this afternoon this has become a paper-to-be.
Mike: OK, Heinrich, but the Muybridge photos (and many others, including one on John H.’s homepage) show that elephants habitually flex the wrist in normal locomotion, not just when gwetting up from resting or when avoiding obstacles. Why?
The interesting thing here is that this is evidence of how flawed our (or maybe just my) intuition is: looking at an elephant skeleton, I don’t think I would ever have guessed that it would walk that way. (That said, the sauropod wrist skeleton does look much less flexible than that of the elephant.)
Matt: (why elephants flex their wrists) Possibly for simple energetics. If the limb is not to hit the ground during the swing phase, it has to be shortened relative to the stance limb. So it has to be bent. Bending the limb at the more proximal joints means lifting more weight against gravity. Flexing the wrist more might be a way to flex the elbow less.
(sauropod wrists look less flexible) Right, but from the texture of the ends of the bones we already suspect that sauropods had thicker articular cartilage caps than do mammals. And remember the Dread Olecranon of Kentrosaurus (i.e., Mallison 2010:fig. 3).
Mike: No doubt, but that doesn’t change the fact that elephant wrists have about half a dozen more discrete segments.
Matt: Most of which are very tightly bound together. The major flexion happens between the radius and ulna, on one hand, and the carpal block on the other, just as in humans. Elephants may have more mobile wrists than sauropods did–although that is far from demonstrated–but if so, it’s nothing to do with the number of bony elements. [Loxodonta skeleton below from Wikipedia, discovered here, arrow added by me.]
(Aside: check out the hump-backed profile of the Asian Elephas skeleton shown previously with the sway-backed profile of the African Loxodonta just above–even though the thoracic vertebrae have similar, gentle dorsal arches in both mounts. I remember learning about this from the wonderful How to Draw Animals, by Jack Hamm, when I was about 10. That book has loads of great mammal anatomy, and is happily still in print.)
And that’s as far as the discussion has gotten. The Dread Olecranon of Kentrosaurus is something Heinrich pointed out in the second of his excellent Plateosaurus papers (Mallison 2010: fig. 3).
Heinrich’s thoughts on articular cartilage in dinosaurs are well worth reading, so once again I’m going to quote extensively (Mallison 2010: p. 439):
Cartilaginous tissues are rarely preserved on fossils, so the thickness of cartilage caps in dinosaurs is unclear. Often, it is claimed that even large dinosaurs had only thin layers of articular cartilage, as seen in extant large mammals, because layers proportional to extant birds would have been too thick to be effectively supplied with nutrients from the synovial fluid. This argument is fallacious, because it assumes that a thick cartilage cap on a dinosaur long bone would have the same internal composition as the thin cap on a mammalian long bone. Mammals have a thin layer of hyaline cartilage only, but in birds the structure is more complex, with the hyaline cartilage underlain by thicker fibrous cartilage pervaded by numerous blood vessels (Graf et al. 1993: 114, fig. 2), so that nutrient transport is effected through blood vessels, not diffusion. This tissue can be scaled up to a thickness of several centimeters without problems.
An impressive example for the size of cartilaginous structures in dinosaurs is the olecranon process in the stegosaur Kentrosaurus aethiopicus Hennig, 1915. In the original description a left ulna (MB.R.4800.33, field number St 461) is figured (Hennig 1915: fig. 5) that shows a large proximal process. However, other ulnae of the same species lack this process, and are thus far less distinct from other dinosaurian ulnae (Fig. 3B, C). The process on MB.R.4800.33 and other parts of its surface have a surface texture that can also be found on other bones of the same individual, and may indicate some form of hyperostosis or another condition that leads to ossification of cartilaginous tissues. Fig. 3B–D compares MB.R.4800.33 and two other ulnae of K. aethiopicus from the IFGT skeletal mount. It is immediately obvious that the normally not fossilized cartilaginous process has a significant influence on the ability to hyperextend the elbow, because it forms a stop to extension. Similarly large cartilaginous structures may have been present on a plethora of bones in any number of dinosaur taxa, so that range of motion analyses like the one presented here are at best cautious approximations.
One of the crucial points to take away from all of this is that thick cartilage caps did not only expand or only limit the ranges of motions of different joints. The mistake is to think that soft tissues always do one or the other. The big olecranon in Kentrosaurus probably limited the ROM of the elbow, by banging into the humerus in extension. In contrast, thick articular cartilage at the wrist probably expanded the ROM and may have allowed the strong wrist flexion that some artists have restored for sauropods. I’m not arguing that it must have done so, just that I don’t think we can rule out the possibility that it may have. And so the flipped-back wrist in the Sideshow Apatosaurus does not bother me–but not everyone is convinced. Welcome to science!
Ever since I saw Jensen’s (1987) paper about how mammals are so much better than dinosaurs because their limb-bones articulate properly, I’ve been fuming on and off about this — the notion that the clearly unfinished ends we see are what was operating in life. No.
Finally, interest in articular cartilage is booming right now, as Mike blogged about here. In addition to the Dread Olecranon of Kentrosaurus, see the Dread Elbow Condyle-Thingy of Alligator from Casey Holliday’s 2001 SVP talk, and of course the culmination of that project in Holliday et al. (2010), and, for a more optimistic take on inferring the shapes of articular surfaces from bare bones, read Bonnan et al. (2010).
Next time: texture and color.
- Bonnan, M.F., Sandrik, J.L., Nishiwaki, T., Wilhite, D.R., Elsey, R.M., and Vittore, C. 2010. Calcified cartilage shape in archosaur long bones reflects overlying joint shape in stress-bearing elements: Implications for nonavian dinosaur locomotion. The Anatomical Record 293: 2044-2055.
- Graf, W., Waele, C. de, and Vidal, P.P. 1995. Functional anatomy of the head−neck movement system of quadrupedal and bipedal mammals. Journal of Anatomy 186: 55–74.
- Holliday, C.M., R.C. Ridgely, J.C. Sedlmayr and L.M. Witmer. 2010. Cartilaginous epiphyses in extant archosaurs and their implications for reconstructing limb function in dinosaurs. PLoS ONE 5(9): e13120. doi:10.1371/journal.pone.0013120
- Mallison, H. 2010. The digital Plateosaurus II: An assessment of the range of motion of the limbs and vertebral column and of previous reconstructions using a digital skeletal mount. Acta Palaeontologica Polonica 55 (3): 433–458.
- Taylor, M.P., Wedel, M.J. and Naish, D. 2009. Head and neck posture in sauropod dinosaurs inferred from extant animals. Acta Palaeontologica Polonica 54(2): 213-220.
- van der Leeuw, A.H.J., Bout, R.G., and Zweers, G.A. 2001. Evolutionary morphology of the neck system in ratites, fowl, and waterfowl. Netherlands Journal of Zoology 51(2):243-262.
- Vidal, P.P., Graf, W., and Berthoz, A. 1986. The orientation of the cervical vertebral column in unrestrained awake animals. Experimental Brain Research 61: 549-559.
September 27, 2011
Preparing a talk is a time-consuming process, and there’s no question that getting the slides ready is where the bulk of that time goes. But unless you understand exactly what it is that you’re going to talk about, even the best slides won’t rescue your talk from mediocrity, so before you fire up PowerPoint, go and read part 1 of this tutorial, on finding the narrative. Seriously. The slides are how you convey your message, and they’re important. But not as important as what your message is.
Assuming you know what story you’re trying to tell, here is the overriding principle of slide design: make yourself understood. Remember again that you have something less than twenty minutes in which to make your rich, complex research project understood to a hall full of strangers who have just sat through five or ten or fifteen other presentations. They will be mentally tired. Help them out. Make every slide tell a clear story.
The slides for a conference talk are science, not art. That doesn’t mean they have to be ugly — of course it doesn’t. But it does mean that whenever you find yourself facing a choice between clarity and beauty, go with clarity.
That means you do not want your slides to look like this:
OK, that is not even beautiful. But it does illustrate some horrible mistakes, and we’ll touch on all of them in what follows. For now, just remember that the purpose of a Results slide is to help the audience know what your results were.
So how do you make yourself understood?
1. Use the full size of the screen
Most importantly, don’t “frame” your content. You have a specific amount of space in which to present your work. Don’t throw any of it away. Although the super-bad slide above may look extreme, I have seen plenty to slides that present, say, specimen photos in about the same amount of space as the graph above occupies. So, then:
- No picturesque borders.
- We don’t need the talk title, or your name or address on every slide. You can tell us once at the start of the talk and then, if you like, once more at the end. If we truly forget who you are in the middle, we can always look at the programme. If we forget what you’re talking about, then your talk has more profound problems.
- That goes double for logos. We do not need to see the following more than once (or indeed once):
- Your institution’s crest
- The conference logo
- Logos of funding bodies
We don’t need any of that stuff, and all of it wastes precious real-estate. Space that you could be using to tell your story.
Most important of all: use as much space as you can for your images. Specimen photographs, interpretive drawings, reproduced figures from the literature, graphs, cladograms, strat sections — whatever you’re showing us, let us see it.
In my own talks, I like to make the picture fill the whole slide. You can usually find a light area to put a dark text on, or vice versa. I often find it’s useful to give the text a drop-shadow, so that it stands out against both light and dark background. (You can find that option in Format -> Character… -> Font Effects if you use OpenOffice, and no doubt somewhere similar in PowerPoint.)
If the aspect ratio of an image that I want to use is not the 4:3 that projectors give you, then I will often crop it down to that aspect ratio, if some of the edges of the image are dispensable, so that the cropped version is properly shaped to fill the screen.
(On image resolution: most projectors seem to be 1024 x 768, maybe some these days are 1280 x 960. There’s no point using images at a higher resolution than that: your audience won’t see the additional information.)
Hopefully you won’t need too many words on your slides, since you’ll be talking to us about what we can see. But what words you use, we need to see. Specifically, this means:
- Use big fonts. There is absolutely no point in showing us an eighty-taxon phylogenetic tree: we just won’t be able to read the taxon names. I tend to make my fonts really big — 32-point and up, which actually is probably bigger than you really need. But you don’t want to be smaller than 20-point at the absolute minimum.
- Use high contrast between the text and background. That usually means black on white, or (if you must) white on black. Well, OK — it doesn’t literally have to be black, but it needs to be a very dark colour (I often use very dark blue). And it doesn’t literally have to be white, but it needs to be a very light colour. (I occasionally use a very pale yellow “parchment”-type colour, but less often.) Do not use grey text or a grey background. Especially do not use grey text on a grey background, even if they are fairly different greys and the muted effect looks classy. You’re not shooting for “classy”, you’re shooting for “legible”. Because you remember the prime directive that you’re trying to make yourself understood.
- If for some reason you must use a non-black, non-white text or background, don’t make it a highly saturated colour. Some combinations, such as a red on blue, and virtually impossible to read.
- No vertical writing (with the possible exception of short y-axis labels on graphs). If your cladogram’s taxon names are vertical, turn your cladogram around. Redraw it if necessary. If the audience have their heads on one site, you’re doing it wrong.
3. Font Choice
Apart from size, what else matters about fonts?
- Avoid elaborate fonts, such as the URW Chancery L Medium Italic that I used for my name and affiliation in the Bad Slide at the top. They’re hard to read, and at best they draw attention away from the message to the medium.
- Pick a single font and stick with it for consistency. Or if you wish, one serifed font (for body text) and one sans-serif (for headings). But you should have little enough text on your slides that it’s practically all headings.
- Stick to standard fonts which you know will be on the computer that will be displaying your presentation. In practice, the safest approach is it stick to Microsoft’s “core fonts for the web” — which is plenty enough choice.
- You might want to avoid Arial, which is widely considered particularly ugly. Other ubiquitous sans-serif fonts include Trebuchet and Verdana, which are both rather nicer than Arial (though Verdana’s glyphs are too widely spaced to my eye).
- Do not use MS Comic Sans Serif, or no-one will take anything you say seriously. I don’t just mean your talk, I mean ever, for the rest of your life.
Why is it important to stick to standard fonts? Because of size, spacing and positioning. Your computer may have the super-beautiful Font Of Awesomeness and it might make your slides looks beautiful; but when you run your PowerPoint file on the conference computer, it won’t have Font Of Awesomeness, so it will substitute whatever it thinks is closest — Arial or Times or something. Not only will you not get the visual effect you wanted, but the glyphs will be different sizes, so that your text will run off the edge of the page, or fall right off the bottom.
(Handy household hint for users of Debian GNU/Linux and variants such as Ubuntu. Make sure that you have the MS core fonts installed on your computer, so that OpenOffice can properly display your slides as you’re designing them, rather than substituting. sudo apt-get install ttf-mscorefonts-installer, restart OpenOffice, and you’re good to go.)
4. How many slides?
I need to mention this issue, if only to say that there’s no right answer. I don’t say that lightly: for most slide-design issues, there is a right answer. (Example: should you use MS Comic Sans Serif? Answer: no.) But number of slides has to vary between people to fit in with presentation styles.
I tend to use a large number of slides and whiz through them very quickly — my SVPCA 2011 talk had 80 slides, and in 2010 I had 92 slides. Lots of them are parenthetical, sometimes just a silly joke to make in passing a point that I am already making. If you miss such a slide, it doesn’t really matter: it’s just light relief and reinforcement, not an integral part of the narrative.
But that many-slides-slipping-quickly-past style doesn’t suit everybody. In the eighteen minutes or so that you get to give a talk (allowing a minute for messing about getting set up and a minute for questions), getting through 80 slides in those 1080 seconds gives you an average of 13.5 seconds per slide.
Lots of people prefer to use fewer slides and talk about them for longer. You can give an excellent talk with very few slides if that approach comes naturally to you: step slowly through nine slides, talk about each one for two minutes.
Once you’ve given a few talks you’ll know which approach works best for you, and you can design accordingly. For your first talk, you’re probably best off aiming initially somewhere in the middle — thirty or so slides — and then seeing what happens when you dry-run the talk. (We’ll discuss that next time around.)
I’ve touched on this one already, but it’s best to use as little text as possible. That’s because you want your audience listening to your story, not reading your slides. I used to put a lot of text in my slides, because I wanted the PowerPoint file to stand alone as a sort of a record of the talk. But I don’t do that now, because a talk involves talking (clue’s in the question). I include enough text to remind myself what I want to say about each slide (sometimes just one or two words; often none at all). And I try to make sure there’s enough to let the audience know what they’re looking at if I zoom straight past it. For example:
I used this slide to briefly tell a typical taphonomic story of a sauropod neck. But I didn’t need to say that I was using diagrams of the neck of Sauroposeidon taken from Wedel et al. 2000, so I just shoved that information on the slide for anyone who was interested. That way I didn’t have to break the flow of my narrative to impart this information.
Use a consistent colour palette. If you’ve used dark blue text on white for half of your slides, don’t switch to black on pale yellow for the other half. It’s not a hugely important point, but it all contributes to helping the talk go down smoothly. You’re getting rid of mental speed-bumps that could stop your audience from giving their full attention to the story you’re telling.
Where possible, avoid putting important information at the bottom — in, say, the lower 10-15% of the slide. That’s because the lower part of the screen can sometimes be obscured by the heads of the people in the front rows.
Avoid hatching, which can look terrible on a screen, in a way that’s very hard to predict. In the Sauroposeidon taphonomy slide above, for example, the lost bones are “greyed out” using a flat grey colour rather the close diagonal lines of the original. I knew it would look right on the screen.
Skip the fancy slide transitions, animated flying arrows, and suchlike. It’s just distracting nonsense that no one in the audience (or anywhere else, for that matter) needs to be exposed to. It’s just gross. Also, as with fonts, you may end up giving your talk from a machine with an older version of PowerPoint that doesn’t support the turning of animated pages and the bouncing arrival of arrows and clipart, and then your presentation will either look stupid or fail to run entirely.
You might want to draw highlighting marks on your slides, e.g. circles around the relevant parts of a specimen photos. That will save you having to mess about with the laser pointer later. (I will have much to say about the laser pointer in part 4). I like to show two consecutive slides: one of the unadorned photo, then one that’s identical apart from the addition of the highlight, like this:
Then as I am talking about the first slide, “in order to mount the vertebrae in something approaching a straight line, they had to leave a huge gap between consecutive centra”, I’ll step on to the next one, which highlights what I’m saying. Slick, no? (This is part of why I end up with such high slide counts.)
A pet hate: don’t write “monophyletic clade”. If it’s a clade, it’s monophyletic by definition. “Monophyletic clade” is like “round circle”, “square square” or “boring ornithopod”.
And finally …
Show us specimens. We are vertebrate palaeontologists, and we love vertebrate fossils. No-one goes into the field because of a deep and abiding passion for graphs or for tables of numbers. We understand that from time to time you’ll need to show us those things in order to tell the story, but nothing makes an audience happier than big, clean photos of beautiful specimens.
Well, that’s it — how to make good slides. Next time we’ll look at rehearsing the talk. (It’ll be a much shorter post than this one.)
I’m pleased to announce that Darren has a new paper out (Naish and Sweetman 2011) in which he and fellow Portsmouth researcher Steve Sweetman describe a maniraptoran theropod from the Wealden Supergroup of southern England. It’s represented only by a single cervical vertebra:
This vertebra is described in seven and a bit pages, which means that it’s had nearly three times as much total coverage as Jobaria (Cf. Sereno et al. 1999).
Still, we can hope that Darren and Steve will return to their specimen some time and monograph it properly.
In the mean time, read all about it over on Tetrapod Zoology.
- Naish, Darren, and Steven C. Sweetman. 2011. A tiny maniraptoran dinosaur in the Lower Cretaceous Hastings Group: evidence from a new vertebrate-bearing locality in south-east England. Cretaceous Research 32:464:471. doi:10.1016/j.cretres.2011.03.001
- Sereno, Paul C., Allison L. Beck, Didier. B. Dutheil, Hans C. E. Larsson, Gabrielle. H. Lyon, Bourahima Moussa, Rudyard W. Sadleir, Christian A. Sidor, David J. Varricchio, Gregory P. Wilson and Jeffrey A. Wilson. 1999. Cretaceous Sauropods from the Sahara and the Uneven Rate of Skeletal Evolution Among Dinosaurs. Science 282:1342-1347.
Meanwhile, elsewhere on the Internet …
On Tuesday morning, a rather nice article about our recent sauropod-necks-were-not-sexually-selected paper appeared on the BBC web-site. At the time of writing, it’s just topped 100 comments (athough fifteen of those are by me — I wanted to respond to the questions that people were asking).
Here it is, for those who are interested (maybe more in the Q-and-A’s than in the actual article): Evolution, sex and dinosaur necks
December 13, 2010
Here’s another dual-purpose post (part 1 is here), wherein I use some of Brian Engh’s cool art to riff on a related topic (with kind permission–thanks, Brian!). Back when he was first planning his awesome Sauroposeidon life restoration, Brian sent these head studies:
(Note that Brian’s ideas were still evolving at this point, and he roofed the nasal chamber with a keratinous resonating chamber instead of the inflatable sac seen in the finished product. I think both are plausible [not likely, just plausible] and look pretty rad, although the latter is obviously a lot more metal.)
I think these are dynamite, because they show that you can avoid “shrink-wrapped dinosaur syndrome” (SWDS) and still make an anatomically detailed, realistic-looking life restoration. SWDS is what I call the common convention in paleo-art of simply draping the skeleton–and especially the skull–in Spandex and calling that a life restoration. I think it’s a popular technique because you can show off the skeleton inside the animal and thereby demonstrate that you’ve done your homework (especially to an audience that already knows the skeletons*). It gives artists an easy way to add detail to their critters; if you actually slab on realistic soft tissues and lose most of those skeletal and cranial landmarks, you have to come up with something else to make your animals look detailed and visually interesting. And by now it’s been going strong for several decades, so people expect it.
* Without harshing on anyone, I suspect that a lot of consumers of paleo-art have spent more time looking at dinosaur skeletons than looking at live animals and thinking about how much or little of their skeletal structure is visible in life, which may make them susceptible to mistaking “shows a lot of the bony structure” for “biologically realistic”. I suspect that because it was true of me for a good chunk of my life; as usual, the one ranting is ranting mostly at his former self. What cured me was dissecting animals and reading TetZoo–happily, two avenues of self-improvement that are open to everyone.
In the second image above (the one showing the innards) Brian kindly credited me for lending a little assistance. That assistance was mainly in forwarding him my full cranio-centric anti-SWDS rant, which I originally put together for a certain documentary that ended up using almost none of my ideas. I’ve been meaning to recycle it here for ages, and Brian’s new art is just the kick in the pants I needed. Without further ado:
“Sauroposeidon head suggestions no labels.jpg” [above] shows a mock-up of the skull, a traditional restoration of the head, the skull with accurate soft tissues, and an updated restoration. The traditional restoration looks like a lot of paleoart from the past two decades–it looks like someone shrink-wrapped the skull. But this is not what the heads of real animals look like at all. If you look at almost any animal, whether it is a lizard, croc,* turtle, snake, bird, cow, horse, rodent, or human, you can’t see the holes in the skull because they are filled with muscles or air sacs and smoothed over with skin. Here are the 8 specific features I fixed in the updated restoration:
* I got a little carried away here–some of the holes in croc skulls are not hard to make out, because their skin is unusually tightly bound to the very rugose skull. Most dinosaurs didn’t have that same skull texture, and there is little reason to think that their heads were similarly shrink-wrapped. Abelisaurs, maybe. Sauropods, not so much.
(1) the profile of the top of the head and start of the neck would have been smoothed out by jaw muscles bulging through holes in the top of the head (strange but true), and by neck muscles coming up onto the back of the skull.
(2) The fleshy nostril should be down on the snout at the end of the nasal troughs. The bony nostrils make that huge hump on top of the head, but they are continuous with these two grooves that run down the front of the face, and almost certainly the whole bony-nostril-plus-groove setup was covered by soft tissues and the actual air holes were down on the snout. That fleshy covering would have been propped up and not sucked down tight to the skull, so you wouldn’t be able to see the boundaries of bony nostrils from the outside. The fleshy nostril should also be fairly big; it is unlikely that a 50-ton animal with a head a yard long had nostrils the size of a horse’s.
(3) The holes in the skull should not be visible. The habit of drawing and painting dinosaurs with shrink-wrapped heads is so entrenched that smooth heads look undetailed and a little fake, but smooth heads are undoubtedly more accurate. The head wasn’t necessarily a completely smooth bullet–it probably had decorative scales and patches of color–but we can be fairly certain that the holes in the skull were not visible through the skin.
(4) The jaw joint is all the way at the back of the head, but past the tooth row the upper and lower jaws were bound together by jaw muscles. When the jaws opened, as shown in the lower images, the muscles were covered by skin. This skin might have been outside the jaws and stretchy, as shown in the attached image “bird cheeks.jpg”, or it might have been tucked in between the jaws as shown in “croc cheeks.jpg” [below].
Another caveat in my own defense: I know that condors do not have muscular, mammal-style cheeks, so the “cheek” skin here is doing more than just covering jaw muscles (farther back on the jaw the skin is covering jaw muscles). Remember that I was writing quick art suggestions for a less technically sophisticated audience, not a dissertation on condor heads. The take home point is that you can’t tell from looking at the condor below where the jaw muscles start or where the jaw joint is located (unless you already know something about bird skulls). Other than the gross outline, there simply isn’t much osteology on display–and this is a naked head!
(5) The eyes are usually reconstructed as small, dull, and centered in the vertical middle of the eye socket. In fact the eyes were probably located toward the top end of the eye socket, they were probably colorful as in most reptiles and birds, and they may have been pretty big. [But not that big; see Mickey's comment below, and note that Brian got it right anyway.]
(6) The external ear hole is usually left out. It should be behind the back of the skull and in front of the hindmost jaw muscles.
(7) The profile of the back of the head follows jaw muscles, not the boundaries of the skull bones.
(8) Sauropods had true flip-top heads. The skull of Giraffatitan looks like nothing so much as an upside down toilet bowl, with the toilet seat for the lower jaw. Sauropods probably used that big gape to shove in as much plant material as possible per unit time. Crocodiles and many birds have an extensible throat pouch that allows them to bolt larger bites than you’d think, and the same was probably true of most dinosaurs, especially sauropods. There may have been a visible division between the muscular neck and this fleshy “gullet”. See “croc throat.jpg” and “bird throat.jpg” [below].
I think you could safely put on a lot more color. People are used to big animals being dull, but that’s because most big animals are mammals and, except for primates, all mammals are effectively colorblind. So big mammals are a horrible guide to how colorful other big animals might be. Komodo dragons and crocs are both fairly dull, but they’re all ambush predators and they have to be dull or they don’t eat. If I get inspired I might take your Sauroposeidon into Photoshop and color it up; otherwise maybe have your artists look at tropical birds, toss back a couple of stiff drinks, and throw caution to the wind.
December 10, 2010
These are happy times for me. Dinosaur rap god and burgeoning paleoartist Brian Engh, AKA The Historian Himself, has finished a new life restoration of Sauroposeidon. Here’s a smallish view, just to give you a taste; for the high resolution awesomeness, check out Brian’s post here. While you’re over there, check out his line of mini-brachiosaur sculptures–the perfect gift for the sauropod-lover in your life (
the a black one is already mine).
As you might guess from the quality of the finished product, this was a project with a long gestation. Brian got in touch with me back in the summer of 2009 and we started swapping ideas on doing life restorations of sauropods. Brian incorporated some of that discussion in his blog post.
Did Sauroposeidon really look like this? Probably not. There’s no direct evidence for inflatable display structures in sauropods or in any other non-avian dinosaurs that I know of. But any life restoration of a dinosaur involves going out on a limb and positing things for which we have little or no direct evidence. So no life restoration is going to show exactly how Sauroposeidon looked. In my view, if you know you’re going to be wrong anyway, you might as well be interestingly wrong, and put in the kinds of plausible-but-not-fossilized structures that extant animals are replete with.
The larger, slightly more serious question then becomes, were big sauropods more likely to be visually flamboyant or big gray pachyderms? I think there is a case to be made for flamboyant sauropods, and I made it in the cover description for this paper (that illustration, by Brian Ford, is below). You can get the PDF for the full argument, but Brian Engh (hmm, just noticed the high correlation between Sauroposeidon life restorations and paleoartists named ‘Brian’) summarized it in eight words: “Brachiosaurs were big. Maybe too big for camouflage.”
The idea of flamboyant sauropods is a hypothesis, and for now a mostly untestable one. I could be wrong. I don’t have a lot invested in it. Flamboyant sauropods would be awesome, and there are already plenty of sauropod life restorations from the Big Gray Pachyderm school, so I’m happy to camp out the other end of the spectrum just for the heck of it. If doing so emboldens those who are trying to kick us in the brainpans with their paleoart, that’s a win-win. I’m not trying to take any credit here–far from it–just happy that the Brians and I have gotten to make common cause.
To make a clean sweep with this post, there is one other Sauroposeidon life restoration that I’ve had the good fortune to be involved with. That one is part of the “Cretaceous Coastal Environment” mural that Karen Carr painted for the Oklahoma Museum of Natural History, an excerpt of which appears below (from this paper again, or see the full version on Karen’s website). While she was working on the mural, Karen sent me a draft illustration of Sauroposeidon for comment. My reply was basically, “Looks awesome. How about some spines?” Given the presence of dermal spines in diplodocids and armor in some titanosaurs, I don’t think it’s unreasonable to infer some kind of dermal ornamentation even in those sauropod taxa for which we have no direct evidence of it. I like Karen’s ground-level shot of the distant sauropods (that’s a squirrel-sized Gobiconodon in the foreground) because they look vast, like gods, and I think that’s how they would strike us if we could stand near them today.
Those aren’t all of the Sauroposeidon life restorations out there–Bob Nicholls has done a very sharp one, which unfortunately does not seem to be currently available on his webpage, and there are others–those are just the three I’ve had some small part in. It’s been a thrill, every time, to work with smart, talented, and hardworking people who can do something special that I can’t, which is bring the vanished world to life. When I was a kid, I didn’t want to just learn about dinosaurs, I wanted to see dinosaurs. I wanted to be a chrononaut. I ended up as a paleontologist because that’s the closest you can get to exploring in time.
So, thank you, Brian (and Brian, and Karen, and Bob, and others) for gracing Sauroposeidon with your skill. It’s phenomenal to get to see my favorite dinosaur with fresh eyes. And thanks to all the rest of you paleoartists out there, paid or unpaid, for your service as our eyes and ears in the past, for letting the rest of us get our mental boots muddy in worlds that we often approach only clinically. Keep those dispatches coming–we can’t wait to see where you’re going to take us next.
April 1, 2010
This is an actual page from the late, lamented Weekly World News, from December 14, 1999. I always thought it was pretty darned funny that they had the alien remains discovered in the “belly” of an animal known only from neck vertebrae. Now, subjecting a tabloid story to technical scrutiny really is like dancing about architecture, but…it just tickles me. As does the entire story. I haven’t been able to get hold of Dr. Posvby to confirm his findings, but it’s been over a decade and he still hasn’t published, so I’m not holding my breath.
December 22, 2009
Ever since we started working on Sauroposeidon, Rich Cifelli and I dreamed of seeing the reconstructed neck on display. That vision has come to fruition.
The Oklahoma Museum of Natural History opened a totally new building in 2000. Coincidentally, the opening ceremony for the new digs was held the same week that the paper naming Sauroposeidon came out in JVP. The exhibits in the new building were pretty cool right out of the gate, but the exhibit people have not been idle, and if you haven’t been there in a year or three you will find many things that you have not seen before.
My favorite upgrade is the new orientation gallery, which introduces museum visitors to the functions of the museum and the kinds of work that go on in the research wing, including most of the traditional -ologies. The reconstructed neck and head of Sauroposeidon hang from the ceiling, spanning most of the length of the gallery and extending out into the museum’s great hall.
The beast was reconstructed by Research Casting International. I got to visit their workshop in Ontario, Canada, a little over a year ago to see how things were coming along. The people there were extremely serious about getting things right (how refreshing!). We spent quite a while talking about how Sauroposeidon was different from Giraffatitan (RCI remounted the Humbolt dinos) and sketching out what the missing bits might have looked like, especially the skull.
Of course we don’t have any skull material from Sauroposeidon, but we do have skulls and partial skulls from several other basal titanosauriforms. Together with one of the people working on the Sauroposeidon project, I filled up a couple of pieces of paper with sketches showing what a slender mid-Cretaceous brachiosaur might have looked like. In particular, and in keeping with the gracility of the cervical vertebrae, we narrowed the skull a bit to get rid of the dreaded Giraffatitan Toilet-Bowl Head.
The completed neck and head were already mounted in the OMNH when I visited last Christmas, but the gallery wasn’t open yet so all I got–and all I could pass on to you–was this teaser. The new orientation gallery opened in the middle of this spring, so Sauroposeidon has been hanging out there for a while. This is just the first chance I’ve gotten to go see my baby.
What a fine present. Merry Christmas from the SV-POW!sketeers!
Update from Mike
Here is my Christmas card to you all.
December 15, 2009
So I finally got to see the Discovery Channel’s new series, Clash of the Dinosaurs. The show follows the common Discovery Channel MO of cutting between CGI critters and talking heads. I’m one of the talking heads, and I get a lot of air time, and I suppose I should be happy about that. But I’m not, for reasons I’ll explain.
I need to preface what follows by saying that I thought the other talking heads did a great job. My experience suggests that the scientific problems with the series didn’t originate with the scientists, infrasound weapons excepted. Tom Holtz–another of the talking heads, and a good one–nailed it on the DML:
For those going to watch the show, a warning:
The documentarians often take anything that any of the talking heads speculated about, and transformed these into declarative statements of fact. In some cases this is particularly egregious, because I strongly disagree with some of these statements and believe the facts are against some of these (say, about tyrannosaurid cranial kinesis…) and they present these as facts rather than suppositions.
In the fall of 2008 the folks at Dangerous Ltd, a London-based film production company, asked me if I’d be interested in being part of a new documentary project, which had the working title “Dino Body” (this isn’t a trade secret or anything, that title was on the Dangerous webpage for months). The grand idea was to show how much we’ve learned about how dinosaurs actually lived.
Now, this is something I care about a lot. In the past couple of decades we’ve learned about the physiology, diets, nesting habits, growth rates, and social lives of dinosaurs, in unprecedented detail. Things no one predicted and that I would have bet heavily against, like burrowing dinosaurs, four-winged raptors, and comparative studies of dinosaur and pterosaur genomes, are backed by solid evidence. We are in a golden age of dinosaur paleobiology, and new discoveries, even new kinds of discoveries, are stacking up faster than I can really keep up. So it would be a great time to bring all this new evidence to the public.
In the late 2008 and early 2009 I spent a LOT of time with the people at Dangerous Pictures, going over all kinds of questions about dinosaur biology. I sent them papers, links to blog posts, diagrams, you name it. They seemed really keen to get the science right, and I was hopeful that we’d get a dinosaur documentary that wasn’t overly speculative sensationalized BS.
Sadly, that hope was to be mercilessly crushed.
The series has some obvious faults. It is incredibly repetitive, to the point that I found it hard to watch for any length of time without my attention wandering. Not just the CGI clips, but the narration as well. You’ll learn in 30 seconds why females tend to be choosier about mates than males (eggs are more expensive than sperm), and spend the next 15 minutes having that slowly beaten in your brain using as much empty verbiage as possible. Ditto every other fact on the show.
More galling are the places where animation is cleverly cut with talking head bits so that we end up describing things that were never in the script. I explained on camera about the unavoidably high mortality among juvenile sauropods, and how groups of Deinonychus could probably pick off the baby sauropods like popcorn. I had been speaking of hatchlings, but my words are cut together with a scene–which you’ll see about 15,000 times–of three Deinonychus taking down an elephant-sized subadult Sauroposeidon. In the real world, it would have pulped them. In the dramatically-lit world of Clash of the Dinosaurs, the three raptors inflict a handful of very shallow flesh wounds with their laughably tiny claws and the Sauroposeidon expires theatrically for no visible reason.
(If they really wanted to impress the audience with the implacability of Mesozoic death, they would have shown the three raptors mowing down a field of newly-hatched babies like so much wheat…)
I spent a long time explaining the evidence that sauropods buried their eggs, and at their request I mocked up diagrams showing the possible proportions of a hatchling Sauroposeidon. So naturally the program shows a mother abandoning her eggs in an exposed nest, and then a few minutes later, hatchlings that are perfect miniatures of the adults struggling up out of the ground. I guess they cut the scene in which the Sand Fairy buried the eggs, and lacked the budget to perform the simple morph of the digital model that would have made the babies look like babies, instead of ponderous adults emerging from the Sarlacc pit.
Some may complain that I am picking nits. But what the heck is the point of bringing on scientific advisors if you’re then going to ignore the stuff they tell you? Why not just make the crap up out of the whole cloth? In fact, there is far too much of that in the show. There is no evidence that Quetzalcoatlus could see dinosaur pee with its ultraviolet vision, or that a herd of hadrosaurs could knock over a predator with their concentrated infrasound blasts. Sorry, paleontologists, you’ll be fielding questions about these newly invented “facts” for the next decade at least.
It’s like I had this great working relationship with the researchers, and they were really curious and careful, and we went to great lengths to do the best work we could, and then somewhere in between my filming back in February and the airing of the completed show, all of our diligent work was flushed right down the crapper, and a fresh script was written by a hyperactive child whose only prior preparation was reading Giant-Size X-Men and getting hit on the head a few times.
Do I sound too harsh? I’m just getting started. Let me tell you about the sacral expansion in sauropods.
Back in the Back in the Day
In many sauropods and stegosaurs and a few other archosaurs, the neural canal (the bony tube that houses the spinal cord) is massively enlarged in the sacral vertebrae. This is the origin of the goofy idea that big dinosaurs had a “second brain” back there to control their hind end, because the real brain up front was (supposedly) just too darn tiny and remote. The researchers at Dangerous asked me about this sacral enlargement, and this is what I told them (quoted from an e-mail I sent November 25, 2008):
The sacro-lumbar expansion is possibly the most misunderstood thing in sauropod biology. First, there are two separate things that have been referred to as sacro-lumbar expansions. The first is the slight swelling of the spinal cord in that region in almost all vertebrates, including humans, to accomodate the neurons that help run the hind limbs (you also have a swelling in the spinal cord at the base of your neck to help run your arms). Contrary to popular belief, a lot of your stereotyped actions require little direct involvement from the brain and are instead controlled by the spinal cord. When you walk, for example, most of the motor control is handled by the spinal cord, and your brain only steps in when you have to actually worry about where to place your feet–when you step over a puddle, for example. So there would be nothing remarkable about sauropods using their spinal cords to drive many of their limb movements, this is something that pretty much all vertebrates do, it’s just not widely known to the public. [Aside: this is true. Also, I have heard it claimed that sauropods could not have reared because their brains were too small to coordinate such an action. This was claimed by a non-biologist who evidently doesn't know how the nervous system works.]
The other sacro-lumbar expansion really is an expansion, but it’s not unique to sauropods and it has nothing to do with running the hind limbs. Most birds have a very large expansion of the spinal cord in the sacro-lumbar region called the glycogen body. As the name implies, it stores energy-rich glycogen, but the function of the glycogen body is very poorly understood. It has been hypothesized to be an accessory organ of balance, or a reservoir of compounds to support the growth and maintenance of the nervous system. Since we don’t even know what it does in birds, we’re straight out of luck when it comes to figuring out what it did in sauropods. Here’s a brief overview:
Here’s an explanatory diagram I sent with the message:
This business about the glycogen body caused some consternation and dithering in the production process. They wanted to bring up the second brain because it’s so entrenched in the popular consciousness (i.e., bad dinosaur books), but they were unhappy that the real explanation turned out to be so unsatisfying (“We don’t know what it does, but not that!”). In the end, we did discuss it briefly on camera. I said something like, “There was this old idea that the sacral expansion functioned as a second brain to control the hindlimbs and tail. But in fact, it almost certainly contained a glycogen body, like the sacral expansions of birds. Trouble is, nobody knows exactly what the glycogen bodies of birds do.”
Somebody in the editing room neatly sidestepped the mystery of the glycogen body by cutting that bit down, so what I am shown saying in the program is this, “The sacral expansion functioned as a second brain to control the hindlimbs and tail.” I’m paraphrasing because I don’t have a DVR, but that’s basically it. (Update: my memory was pretty good. Here’s the interview transcript.)
Do you see, do you understand, what they did there? I was explaining why an old idea was WRONG and they cut away the frame and left me presenting the discredited idea like it’s hot new science. How freaking unethical is that?
So. I don’t know if the decision to turn my words around 180 degrees was a mistake made by an individual editor, or if it was approved from someplace higher up the line. I aim to find out. Until I do, I’m boycotting Dangerous Ltd, and I encourage you to do likewise.
The Final Insult
Oh, and they spelled my name wrong, throughout. And also mispelled Sauroposeidon in one of the quiz bits at commercial time. “What does Sauroposeiden mean?” It means you don’t know the Greek pantheon, sauropods, or basic spellchecking, dumbasses.
Science journalism FAIL.
UPDATE, January 27, 2010
This is so perfect that it hurts. For “Science Channel” feel free to substitute any of the ignotainment feeds operated by Discovery Communications.
December 7, 2009
Broadly speaking, pneumatic sauropod vertebrae come in two flavors. In more primitive, camerate vertebrae, modeled here by Haplocanthosaurus, the centrum is a round-ended I-beam and the neural arch is composed of intersecting flat plates of bone called laminae (lam above; fos = fossa, nc = neural canal, ncs = neurocentral suture; Ye Olde Tyme vert pic from Hatcher 1903).
In more derived, camellate vertebrae, the centrum and neural arch are both honeycombed with many small air spaces. This inflated-looking morphology is very similar to that seen in birds, like the turkey we recently discussed. The fossae and foramina on the outside tend to be smaller and more numerous than in camerate vertebrae, as shown here in a titanosauriform axis from India (Figure 3 from Wilson and Mohabey 2006). The green arrows show that the fossae visible on the external surface are excavations or depressions into the honeycombed internal structure of the bone.
External fossae on bones can house many different soft tissues, including muscles, pads of fat or cartilage, and pneumatic diverticula (O’Connor 2006). Pneumatic fossae are often strongly lipped and internally subdivided and may contain pneumatic foramina, which makes them easier to diagnose (but they may also be simple, smooth, and “blind”, which makes them harder to diagnose as pneumatic). But in all of these cases we are usually talking about the same thing: a visible excavation into a corpus of bony tissue, which may have marrow spaces inside if it is apneumatic, or air spaces inside if it is pneumatic (the corpus of bone, not the dent). That’s probably how most of us think about fossae, and it would hardly need to be explained…except that sometimes, something much weirder happens.
Consider this cervical of Brachiosaurus (this is BYU 12866, from Dry Mesa, Colorado). Brachiosaurus and Giraffatitan have an in-between form of vertebral architecture that my colleagues and I have called semicamellate (Wedel et al. 2000); the centrum does have large simple chambers (camerae), but smaller, thin-walled camellae are also variably present, especially along the midline of the vertebra and in the ends of the centrum. As in Haplocanthosaurus, the neural arch is composed of intersecting plates of bone; unlike Haplocanthosaurus, these laminae are not flat or smooth but are instead highly sculpted with lots of small fossae. Janensch (1950) called these “Aussenkaverne”, or accessory outside cavities, because and they are smaller and more variable than the large fossae and foramina that invade the centrum.
And that’s the weird thing. As the red arrows in the above image show, the “Aussenkaverne” are not excavations or depressions into anything, except the space on the other side of the lamina (which in life would have been occupied by another diverticulum). The neural arches of Brachiosaurus and Giraffatitan are not excavated by fossae, they’re embossed, like corporate business cards and fancy napkins.
What’s up with that!? We tend to think of pneumaticity as reducing the mass of the affected elements, but the shortest distance between two vertebral landmarks is a smooth lamina. These embossed laminae actually require slightly more bony material than smooth ones would.
As you can see above, the outer edges of the laminae are thick but the bone everywhere else is very thin. Maybe, like the median septa in pneumatic sauropod vertebrae, the thin bone everywhere except the edges of the laminae was just not loaded very much or very often, and was therefore free to get pushed around by the diverticula on either side, in the sense of being continually and quasi-randomly remodeled into shapes that don’t strike us as being very mechanically efficient. But also like the median septa, the thin parts of the laminae are only rarely perforated (but it does happen), for possible (read: arm-wavy) reasons discussed in the recent FEA post. And maybe the amount of extra bone involved in making embossed laminae versus smooth ones was negligible even by the very light standards of sauropod vertebrae.
Another question: since these thin sheets of bone were sandwiched in between two sets of diverticula, why are the “unfossae” always embossed into them, in the medial or inferior direction? Why don’t any of them pop out laterally or dorsally, looking like domes or bubbles instead of holes, like Mount Fist-of-God from Larry Niven’s Ringworld? Did the developmental program get accustomed to making fossae that went down and into a corpus of bone, and just kept on with business as usual even when there was no corpus of bone to excavate into? I’m only half joking.
I don’t have good answers for any of these questions. I scanned this vert a decade ago and I only noticed how weird the “unfossae” were a few months ago. I’m putting all this here because “Hey, look at this weird thing that I can only wave my arms about” is not a great basis for a peer-reviewed paper, and because I’d like your thoughts on what might be going on.
In Other News
The Discovery Channel’s Clash of the Dinosaurs premiered last night. I would have given you a heads up, except that I didn’t get one myself. I only discovered it was on because of a Facebook posting (thanks, folks!).
COTD is intended to be the replacement, a decade on, for Walking With Dinosaurs. I’m happy to report that one of the featured critters is Sauroposeidon. I grabbed a couple of frames from the clips posted here.
I haven’t seen the series yet, because I don’t have cable. But I’m hoping to catch it at a friend’s place next Sunday night, Dec. 13, when the entire series will be shown again. With any luck, I’ll have more news next week.
Finally, I got to do an interview at Paw-Talk, a forum for all things animal. I’m very happy with how it turned out, so thanks to Ava for making it happen. While you’re over there, have a look around, there’s plenty of good stuff. Brian Switek, whom you hopefully know from this and this, is a contributor; check out his latest here.
- Hatcher, J.B. 1903. Osteology of Haplocanthosaurus, with a description of a new species, and remarks on the probable habits of the Sauropoda, and the age and origin of Atlantosaurus beds. Memoirs of the Carnegie Museum 2:1–72.
- Janensch, W. 1950. Die Wirbelsaule von Brachiosaurus brancai. Palaeontographica (Suppl. 7) 3:27-93.
- 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, Mathew J., Richard L. Cifelli and R. Kent Sanders. 2000. Osteology, paleobiology, and relationships of the sauropod dinosaur Sauroposeidon. Acta Palaeontologica Polonica 45(4): 343-388.
- Wilson, J. A. and Mohabey, D. M. 2006. A titanosauriform axis from the Lameta Formation (Upper Cretaceous: Maastrichtian) of central India. Journal of Vertebrate Paleontology 26:471–479.
November 24, 2009
I drew a couple of these a while back, and I’m posting them now both to fire discussion and because I’m too lazy to write anything new.
Here’s the neck of Apatosaurus, my own reconstruction based on Gilmore (1936), showing the possible paths and dimensions of continuous airways (diverticula) outside the vertebrae.
Here’s figure 4 from Lovelace et al. (2007), which first got me thinking about pneumatic traces on the ventral surfaces of the centra and what they might imply. You can see pneumatic spaces between the parapophyses in Supersaurus (A) and Apatosaurus (C) but not in Barosaurus (B).
This is another of my moldy oldies, again based on one of Gilmore’s pretty pictures, showing how I think the soft tissues were probably arranged. The muscles are basically the technicolor version of Wedel and Sanders (2002). Two points:
- How bulky you make the neck depends mainly on how much muscle you think was present (which of course depends on how heavy you think the neck was…). Here I was just trying to get the relationships right without worrying about bulk, but it’s worth considering.
- The volume of air inside the vertebra was dinky compared to the probable volume of air outside. In Apatosaurus, either of the canals formed by the transverse foramina has almost twice the cross-sectional area of the centrum.
A fair amount of this has been superseded with better data and prettier pictures by Schwarz et al. (2007), so don’t neglect that work in any ensuing discussion (it’s free, fer cryin’ out loud). And have a happy Thanksgiving!
- Gilmore, C.W. 1936. Osteology of Apatosaurus with special reference to specimens in the Carnegie Museum. Memoirs of the Carnegie Museum 11: 175-300.
- Lovelace, D.M., Hartman, S.A., and Wahl, W.R. 2007. Morphology of a specimen of Supersaurus (Dinosauria, Sauropoda) from the Morrison Formation of Wyoming, and a re-evaluation of diplodocid phylogeny. Arquivos do Museu Nacional, Rio de Janeiro 65(4):527-544.
- Schwarz, D., Frey, E., and Meyer, C.A. 2007. Pneumaticity and soft−tissue reconstructions in the neck of diplodocid and dicraeosaurid sauropods. Acta Palaeontologica Polonica 52 (1): 167–188.
- Wedel, M.J., and Sanders, R.K. 2002. Osteological correlates of cervical musculature in Aves and Sauropoda (Dinosauria: Saurischia), with comments on the cervical ribs of Apatosaurus. PaleoBios 22(3):1-6.
Mike asked me to add the labeled version of Nima’s brachiosaur parade, so here you go. Click to embiggen.