We all remember Upchurch and Martin’s (2002) description of the Rutland Cetiosaurus, which remains by some distance the best British sauropod specimen in the literature; and the same authors’ (2003) survey of the genus Cetiosaurus. They concluded that nearly all of its many named species are either nomen dubia or misassigned, and that only C. oxoniensis is a valid, diagnosable species.
Accordingly, Upchurch and Martin informally used C. oxoniensis as the type specimen in their descriptive work, noting that this usage should be formalised by a petition to the International Commission on Zoological Nomenclature (ICZN).
Six years layer, we submitted that petition to the Bulletin of Zoological Nomenclature; a few months after its publication, positive comments from Paul Barrett and Pete Galton followed.
That was in 2009. Five years of silence followed, as the Commission meditated on our five-page petition. (That’s two pages plus front-matter and references). Today, finally, the results are in! The abstract says it all:
The Commission has conserved the usage of the generic name Cetiosaurus Owen, 1841 by designating Cetiosaurus oxoniensis Phillips, 1871 as the type species of Cetiosaurus in place of Cetiosaurus medius Owen, 1842.
So Cetiosaurus finally has a decent type species! Two cheers for the Commission!
I’d always assumed that ratifying the petition would be a no-brainer once the Commission got around to examining it. In fact, their report makes it clear that’s not how it was at all. 16 members voted for the proposal, eight voted against and two abstained. So I guess we were only three switched votes away from having the proposal rejected. Which would frankly have been stupid: every sauropod worker would just have carried right on using C. oxoniensis as though it were the type species anyway.
Why would anyone vote against, you ask? I asked myself the same question. Happily, the decision explains the objections in detail. They nearly all seem to come down to complaints that we didn’t clearly enough explain why C. medius was the previous type species. There’s a reason for that: the truth is that the literature is so vague and contradictory that no-one really knew what the heck the type species was — which is one of the reasons we needed to establish one. (Upchurch and Martin 2002:1053 thought C. brevis was the type; as we investigated this in more detail for the petition, we concluded that the claim of C. medius was stronger. But still very weak.)
But all of that seems like pointless pithering to me. Who cares what the type species was? The point of the petition is to establish what it is, and only one Commission member expressed any reservations about the case we’d made — which is basically that C. oxoniensis is what’s always used in comparisons.
Anyway, dissenting opinions notwithstanding, the genus Cetiosaurus now stands before us having been made an honest woman at long last.
… all of which leaves us with the question of what the Rutland cetiosaur is. It’s been assumed to be Cetiosaurus all along, and that identification has to stand until someone publishes a case to the contrary. But there do seem to be persistent rumours that someone somewhere thinks it’s something different. I wonder if anything will ever come of it?
- International Commission on Zoological Nomenclature. 2014. OPINION 2331 (Case 3472): Cetiosaurus Owen, 1841 (Dinosauria, Sauropoda): usage conserved by designation of Cetiosaurus oxoniensis Phillips, 1871 as the type species. Bulletin of Zoological Nomenclature 71(1):48-50.
- Naish, Darren, and David M. Martill. 2007. Dinosaurs of Great Britain and the role of the Geological Society of London in their discovery: basal Dinosauria and Saurischia. Journal of the Geological Society, London 164:493-510 (Bicentennial Review issue)
- Upchurch, Paul and John Martin. 2002. The Rutland Cetiosaurus: The Anatomy and Relationships of a Middle Jurassic British Sauropod Dinosaur. Palaeontology 45(6):1049-1074.
- Upchurch, Paul, and John Martin. 2003. The anatomy and taxonomy of Cetiosaurus (Saurischia, Sauropoda) from the Middle Jurassic of England. Journal of Vertebrate Paleontology 23:208-231.
- Upchurch, Paul, John Martin, and Michael P. Taylor. 2009. Case 3472: Cetiosaurus Owen, 1841 (Dinosauria, Sauropoda): proposed conservation of usage by designation of Cetiosaurus oxoniensis Phillips, 1871 as the type species. Bulletin of Zoological Nomenclature 66(1):51-55.
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 side, 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 look 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.)
October 11, 2010
You may remember that when I wrote about Amphicoelias diplobrontobarowassea the other day, I rather ungraciously complained that “I don’t want to talk about that. There are other things I do want to talk about”. Well, with A. suuwatorneriosaurodocus now firmly dealt with, I can talk about what I wanted to — which is Taylor (2010), a little number that I like to call Sauropod dinosaur research: a historical review. You can download the PDF from my website (more on that subject next time) and get the high-resolution versions of the figures separately if you wish.
It’s a comprehensive history of research into sauropod dinosaurs, starting in 1831 with the genera Cardiodon and Cetiosaurus, and bringing us right up to 2008 (which is when the paper was accepted — see below). I cover this history in five stages:
- Stage 1: early studies, isolated elements (1841-1870)
- Stage 2: the emerging picture (1871-1896)
- Stage 3: interpretation and controversy (1897-1944)
- Stage 4: the dark ages (1945-1967)
- Stage 5: the modern renaissance (1968-present)
You could say the the main part of the story begins with Phillips’s (1871) description of Cetiosaurus oxoniensis, the first reasonably complete sauropod, and really kicks into gear with the Marsh-Cope bone wars, but there are plenty of twists and turns between then and now, including — finally — the publication of the table of brachiosaur mass-estimates that I alluded to back in Xenoposeidon week. [Executive summary: published estimates for the single individual HMN SII have varied by a factor of 5.75. Wow.]
History of the history paper
This paper had its genesis in the one-day conference convened at the Geological Society of London on 6 May 2008. [Announcement on Tetrapod Zoology; Tet Zoo report part 1 and part 2]. The extended abstract of my talk has been on my web-site for a long time, and was included in the rather handsome abstracts volume of the conference — which has now been superseded by the proceedings volume containing the full-length papers of which mine is one.
We’d been told to prepare 30-minute talks — a much heftier slot than the 20 minutes we get at SVPCA (or indeed the 15 allowed at SVP, though I wouldn’t know what that’s like as I have never, ever managed to get a talk accepted there). I tend to move very quickly through my talks anyway, so I prepared a monster presentation of 76 slides (plus another 11 that I had to cut from the talk, but which I left hanging around at the end of the slideshow). By the way, this is the very talk that my wife, Fiona, fell asleep in the middle of while I was rehearsing it at her.
So I’d prepared a thirty-minute talk that used every second of every minute. Then on the day of the conference itself, they handed out the schedules, and … the talks were down to twenty-five minutes. Arrrgh! I had absolutely no fat to trim in my thirty minutes, so all I could do was talk even faster, and keep going when I reached the 25-minute mark.
So there I was, talking about how Russell and Zheng (1993) pioneered the use of cladistics in sauropod systematics, when the session moderator — our very own Darren Naish — started trying to wave me off the podium. By the time I was talking about Sander’s (2000) work on the long-bone histology of Tendaguru-Formation sauropods, Darren was edging on to the stage, trying to bring my talk to an end by making moves for the microphone, while I was talking faster and faster in manner more than a little reminiscent of Monty Python’s microphone-stealing sketch.
Poor Darren. I actually don’t quite recall how things ended up, but as far as I know I got through all my slides before being persuaded to retire, and here for your edification is the Conclusions slide.
Anyway, with the conference over, all of us who’d given talks were invited to contribute papers to a proceedings volume, and that’s what’s just come out. (According to the Geological Society’s own page, the book won’t be available to buy until 19 November, but all the PDFs are available to download to those who have the relevant access rights.)
Is my paper worth reading? For seasoned palaeontologists, much of what I cover is going to be familiar ground, though I hope most people will find one or two nuggets of interesting new information in there. But perhaps it will be most useful as a primer for people new to the field, or first approaching sauropods having previously worked on other groups.
Edited volumes vs. journals
You know how some with papers, you submit them, they go through review and then … nothing? I’ve heard horror stories of papers that have been in press for ten years or more, and I am relieved to say that I’ve never experienced that kind of delay. But the reviewed, revised and resubmitted version of my sauropod-history manuscript was accepted and in press as of January 2009, so this has been the best part of two years coming.
I think this is pretty much standard for edited volumes, because they are basically stalled until all the contributing authors have got their jobs done. To be fair to the Geological Society, who were the publishers in this case, I think they’ve done a nice job on the layout, and they got all my proof corrections done. But still: nearly two years in press is a looong time. And the end result is that the paper is in a book that most people will consider very expensive — $190 at amazon.com, £95 at amazon.co.uk — which means that fewer people will read it than I would like. (I will talk more about the price in a subsequent post.)
So would I do it again? This paper is my first contribution to an edited volume, and although I’m pleased to have done it this time, I think it will take a particularly special opportunity for me to do it again: a book that I wouldn’t want not to be in, such as another of the all-sauropods-all-the-time volumes that glutted our shelves in the glorious year of 2005.
Journals are fundamentally wired to move faster: they handle manuscripts on an individual basis, then push out a volume according to a schedule, and your work goes in as soon as there’s a free slot. That can hardly help but be a more efficient model than the edited-volume approach where, however efficiently I get my work done, it can’t be published until 21 other authors have done theirs.
For a much more distressing example, consider my two remaining in-press manuscripts, those defining the clades Sauropoda and Sauropodomorpha for the PhyloCode companion volume. (These are multiple-author works, as we wanted to represent a consensus view among multiple sauropod/sauropodomorph workers.)
I was first invited to put together the Sauropoda entry on 5 March 2007, and told to send it “at your earliest convenience”. I’d put together an initial draft by 11 March, which I circulated to all the co-authors on that date. Because of the wording of the invitation, I told the co-authors that “timelines are very tight for this work — I really need to get a submission back to the editors within a week or so. So if you’re in a position to contribute, I’d appreciate it if you could do so as soon as possible.” Then on 12 March, we were invited to contribute the Sauropodomorpha entry as well, so we worked on both of these in parallel.
All five authors worked hard and quickly on multiple drafts of both of these entries, and we bashed our way through real — though polite — disagreements about the most appropriate definitions to use. (I’ll say right now that it was a pleasure to work with all the co-authors, and I would be delighted to work with any of them again if the opportunity arose.) Because of the difficulties of co-ordinating the work across three continents, it took a little longer than we’d hoped to get the manuscripts finished and polished, but we submitted them both on 17 April, 43 days after the initial invitation was issued.
And now here we are, three and a half years later, and nothing has happened. For all I know, the authors haven’t even all submitted their manuscripts yet — I know they hadn’t a year ago, we can only hope that another twelve months has been long enough for them to get their fingers out.
Really. It makes you want to weep.
And now, on to a happier thought:
My dissertation is 60% published!
I was very taken with Andy Farke’s recent post Crossing the Finish Line for the Dissertation on his fine blog, The Open Source Paleontologist. In it, he celebrates the fact that all the chapters of his dissertation have now been published as peer-reviewed papers. As I said in a comment, I like the perspective that you’re not really done with your dissertation until you’ve made it redundant. I’ve heard too many tales about people who sit on their dissertations for years, always meaning to publish the chapters but never quite getting around to it, until they were obsolete.
So my goal is to avoid that fate. Instead, in emulation of Andy, I want to get all five of my chapters out there in the world as soon as possible. So here’s the score:
- Chapter 1. Sauropod dinosaur research: a historical review — published in the Geological Society special volume.
- Chapter 2. A re-evaluation of Brachiosaurus altithorax Riggs 1903 (Dinosauria, Sauropoda) and its generic separation from Giraffatitan brancai (Janensch 1914) — published in JVP.
- Chapter 3. An unusual new neosauropod dinosaur from the Lower Cretaceous Hastings Beds Group of East Sussex, England — published in Palaeontology
- Chapter 4. A new sauropod dinosaur from the Lower Cretaceous Cedar Mountain Formation, Utah, U.S.A. — in review at a journal that, once revisions are submitted, tends to get papers out pretty quickly.
- Chapter 5. Vertebral morphology and the evolution of long necks in sauropod dinosaurs — in revision after having been rejected for what I frankly thought were specious reasons, but let’s not get into that.
With a trailing wind, I could conceivably be finished by the end of the calendar year. But realistically that would have to classified as a optimistic schedule.
Ah well. Onward and upward.
- Phillips, J. 1871. Geology of Oxford and the Valley of the Thames. Clarendon Press, Oxford.
- Russell, Dale A., and Zheng, Zhong. 1993. A large mamenchisaurid from the Junggar Basin, Xinjiang, China. Canadian Journal of Earth Science 30(10/11): 2082-2095.
- Sander, P. Martin. 2000. Longbone histology of the Tendaguru sauropods: implications for growth and biology. Paleobiology 26(3): 466-488.
- Taylor, Michael P. 2010. Sauropod dinosaur research: a historical review. pp. 361-386 in: Richard T. J. Moody, Eric Buffetaut, Darren Naish and David M. Martill (eds.), Dinosaurs and Other Extinct Saurians: a Historical Perspective. Geological Society of London, Special Publication 343. doi: 10.1144/SP343.22
Taylor, M. (2010). Sauropod dinosaur research: a historical review Geological Society, London, Special Publications, 343 (1), 361-386 DOI: 10.1144/SP343.22
For those of you who care about such things, the new issue 66(2) of the Bulletin of Zoological Nomenclature contains two comments on our petition to the ICZN to fix Cetiosaurus oxoniensis as the type species of the historically important genus Cetiosaurus (Upchurch et al. 2009) — both of them supporting the proposal (Barrett 2009 and Galton 2009).
Paul Barrett wrote (in part):
Cetiosaurus was the first sauropod dinosaur to be scientifically described (Owen, 1841) and one of the earliest dinosaurs to be recognised: the taxon is clearly of historical importance and stabilising its taxonomy would represent an important contribution to dinosaur studies.
Cetiosaurus is not only a historically important taxon, but also one that has been used to specify other groups within Dinosauria, including Cetiosauridae. In addition, Ornithischia, one of the major dinosaur sub-groups, has been defined as all dinosaurs that are more closely related to Iguanodon than they are to Cetiosaurus (Norman et al., 2004).
(I’d completely missed that use of Cetiosaurus as an external specifier for Ornithischia, which I suppose just goes to show that I should pay more attention to the ornithischian literature.)
Pete Galton wrote (in part):
It should be noted that the “Monograph of the genus Cetiosaurus” by Owen (1875) is based almost entirely on the Bletchington Station material of C. oxoniensis (Owen even used Phillips’ figures!). Also, as noted by Galton & Knoll (2006), the family CETIOSAURIDAE Lydekker, 1888 is based on C. oxoniensis Phillips, 1871 because Lydekker (1888, p. 137) indicated it as being the type species of Cetiosaurus Owen.
More good arguments there for the conservation of prevalent usage by formally recognising C. oxoniensis.
Anyone else who has strong feelings on this subject, either way, should get them in writing to the Executive Secretary, ICZN., c/o Natural History Museum, Cromwell Road, London SW7 5BD, U.K. (e-mail: email@example.com).
- Barrett, Paul B. 2009. Comment on the proposed conservation of usage of Cetiosaurus Owen, designation of Cetiosaurus oxoniensis Phillips, 1871 as the type species [comment 1 of 2]. Bulletin of Zoological Nomenclature 66(2): 187-188.
- Galton, Peter M. 2009. Comment on the proposed conservation of usage of Cetiosaurus Owen, designation of Cetiosaurus oxoniensis Phillips, 1871 as the type species [comment 2 of 2]. Bulletin of Zoological Nomenclature 66(2): 187-188.
- Galton, Peter M., and Fabien Knoll. 2006. A saurischian dinosaur braincase from the Middle Jurassic (Bathonian) near Oxford, England: from the theropod Megalosaurus or the sauropod Cetiosaurus? Geological Magazine 143: 905921.
- Lydekker, Richard. 1888. Catalogue of the fossil Reptilia and Amphibia in the British Museum (Natural History), Cromwell Road, S.W. Part 1. Containing the orders Ornithosauria, Crocodylia, Dinosauria, Squamata, Rhynchocephalia, and Proterosauria. British Museum (Natural History), London.
- Norman, David B., Lawrence M. Witmer, and David B. Weishampel. 2004. Basal Ornithischia. pp. 325334 in David B. Weishampel, Peter Dodson and Halszka Osmólska (eds.), The Dinosauria, Second edition. University of California Press, Berkeley and Los Angeles. 861 pp.
- Owen, Richard. 1841. A description of a portion of the skeleton of Cetiosaurus, a gigantic extinct saurian occurring in the Oolitic Formation of different parts of England. Proceedings of the Geological Society of London 3: 457-462.
- Owen, Richard. 1875. Monograph of the Mesozoic Reptilia, part 2: Monograph on the genus Cetiosaurus. Palaeontolographical Society Monograph 29: 2743 and plate X.
- Phillips, John. 1871. Geology of Oxford and the Valley of the Thames. Clarendon Press, Oxford.
- Upchurch, Paul and John Martin. 2002. The Rutland Cetiosaurus: the anatomy and relationships of a Middle Jurassic British sauropod dinosaur. Palaeontology, 45(6): 1049-1074.
- Upchurch, Paul, John Martin, and Michael P. Taylor. 2009. Case 3472: Cetiosaurus Owen, 1841 (Dinosauria, Sauropoda): proposed conservation of usage by designation of Cetiosaurus oxoniensis Phillips, 1871 as the type species. Bulletin of Zoological Nomenclature 66(1): 51-55.
Let’s assume for a moment that you accept our contention (Taylor et al. 2009) that, since extant terrestrial tetrapods habitually hold their necks in maximal extension, sauropods did the same. That still leaves the question of why we have the neck of our Diplodocus reconstruction at a steep 45-degree angle rather than the very gentle elevation that Stevens and Parrish’s (1999) DinoMorph project permits.
As a reminder, here is fig. 6A of Stevens (2002), a paper on the computer science behind DinoMorph which used exactly the same models as the 1999 study but which conveniently illustrates them in lateral view:
As you’ll see, not only does the neutral pose show the characteristic subhorizontal neck with the drooping end, but even the maximally extended pose barely gets the head above the level of the back. In the most recent version of his Diplodocus model, Kent has slightly changed the angle at which the neck leaves the torso, due to a reconfiguration of the pectoral girdle, but this still leaves the neck very low.
So why did we do this?
Doesn’t the DinoMorph model show that the posterior cervicals just can’t do this?
Well, maybe not.
Remember that the precursor to the DinoMorph project was John Martin’s (1987) paper on the mounting of the Rutland cetiosaur at the Leicester City Museum, in which he calculated neutral pose and the extreme extended and flexed poses by manipulating actual bones without the benefit of a computer. Martin ended up with a similar result to that Stevens and Parrish were later to get:
But when Matt and I looked at the actual mounted skeleton a few years back, what we saw didn’t fit with this at all:
Check out that huge gap between the centra of the fourth and fifth cervicals! There’s no way to avoid this without putting a comically extreme downward kink in the neck at this point. And there are similar gaps at other points along the neck, including some near the neck-base that would require a strong upward kink in order to articulate both the centra and the zygapophyses simultaneously.
Are we saying that in life, this specimen did have strong kinks in the neck? No, we’re not (despite the pleasant coincidence that this would force the neck into an extreme version of the elevated pose we’re advocating). What we’re saying is that sauropod cervicals are rarely — I’d go so far as to say never — preserved undistorted, and so you just can’t rely on how they seem to articulate, at least not for quantitative analyses. This post-mortem distortion should not be too surprising: unlike femora and other such solid bones, remember that the cervicals were highly pneumatic and composed primarily of laminae, which would be subject to all sorts of taphonomic and diagenetic distortion. In the extreme case of Sauroposeidon, the cervicals, which were up to 140 cm in length, “are of extremely light construction, with the outer layer of bone ranging in thickness from less than 1 mm (literally paper-thin) to approximately 3 mm” (Wedel et al. 2000:110-111) — it’s astonishing that they are not much more smushed up than they are.
So Martin’s cetiosaur seems too distorted to give meaningful articulation results, but what about the specimens that Stevens and Parrish used for the DinoMorph paper? Well, the Apatosaurus model is certainly based on questionable material. As pointed out by Upchurch (2000):
A second difficulty with Stevens and Parrish’s analysis is that their data for Apatosaurus was derived from a single specimen in the Carnegie Museum (CM 3018). This generally well preserved specimen has suffered severe damage at the base of the neck, and the three most posterior cervicals are thus represented by plaster models that cannot provide reliable anatomical data (Gilmore 1936, pers. obs.). Although Stevens and Parrish acknowledge that the morphology of the posterior cervicals is particularly influential in determining the nature of the feeding envelope, they do not mention this problem, and it is not clear how this gap in the data was addressed in their analyses. This deficit could have had a profound impact on Stevens and Parrish’s conclusions.
And Gilmore’s observations are really rather damning: as well as the account of the damaged neck-base, he also noted (p. 195) that “the type of A. louisae [i.e. CM 3018] lacks most of the spine tops, only those of cervicals eight, ten and twelve being complete”. (You would never guess this from Gilmore’s Plate XXIV, which shows all of the cervicals but C5 essentially complete.) So all in all, the DinoMorph study’s Apatosaurus is not one I’d want to build an argument on.
What about the Diplodocus carnegii holotype CM 84, which is the Diplodocus used in the DinoMorph papers? That’s just about the best preserved sauropod skeleton in the world, right? Well, yes. But even that is distorted enough that the neck can’t be articulated without some sleight of hand. I don’t have good photos of the mounted neck, unfortunately (and probably won’t have until someone at the NHM gives me a stepladder and access to the holy of holies that surrounds the mount), but I did have the experience of photoshopping the cervical vertebra illustrations from Hatcher (1901: plate III) in an attempt to get them into a good pose, and I found that even these don’t really fit properly:
You’ll see that, while the condyles are sat nicely in the cotyles, the zygapophyses are not at all well articulated: in particular, the C7-C8 and C8-C9 junctions have the prezygs shoved much too far forward, so that a double downward kink would be necessary to accomodate these articulations without pulling the condyles out of the cotyles.
Finally, while Matt and I were in Berlin last November, as part of the excursion associated with the awesome all-sauropod-gigantism-all-the-time workshop, we got to play with the superbly preserved set of anterior brachiosaur cervicals HMN SI, and we tried to articulate the real bones. We had to stop for fear of breaking them, because they simply would not fit nicely together.
In conclusion, the distortion of all sauropod cervicals renders them poor subjects for quantitative analysis such as that of the DinoMorph project. While the approach of Stevens and Parrish is a real and valuable contribution to rigour in the analysis of posture, the output of DinoMorph is a hypothesis to be tested by other lines of evidence rather than a firmly established fact. (That last bit was quoted verbatim from our paper.)
I’ve gone on much longer than I intended to in what was supposed to be a quick-and-easy post, so I’ll leave it here. In order to keep the recent paper short and snappy, we didn’t go into this in much detail, summarising down to a mere 88 words (Taylor et al 2009: 216-217), so maybe this will bear repeating (in more rigorous form) in a future publication.
- 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 and plates I-XIII.
- Martin, J. 1987. Mobility and feeding of Cetiosaurus (Saurischia, Sauropoda) why the long neck? In: P.J. Currie and E.H. Koster (eds.), Fourth Symposium on Mesozoic Terrestrial Ecosystems, Short Papers, 154-159. Box-tree Books, Drumheller, Alberta.
- Stevens, K.A. 2002. DinoMorph: Parametric modeling of skeletal structures. Senckenbergiana lethaea 82(1): 23-34.
- Stevens, K.A. and Parrish, J.M. 1999. Neck posture and feeding habits of two Jurassic sauropod dinosaurs. Science 284: 798-800. [Free subscription required]
- 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.
- Wedel, M.J., Cifelli, R.L. and Sanders, R.K. 2000. Sauroposeidon proteles, a new sauropod from the Early Cretaceous of Oklahoma. Journal of Vertebrate Paleontology 20, 109-114.
May 27, 2009
Welcome, one and all, to Taylor, Wedel and Naish (2009), Head and neck posture in sauropod dinosaurs inferred from extant animals. It’s the first published paper by the SV-POW! team working as a team, published in Acta Palaeontologica Polonica, and freely available for download here.
Far, far back in the uncharted depths of history, silly people like Osborn and Mook (1921:pl. 84), Janensch (1950b: pl. 8) and Paul (1988:fig. 1), who didn’t know any better, used to depict sauropods with their necks held strongly elevated.
All that began to change with Martin’s (1987) short paper in the Mesozoic Terrestrial Ecosystems volume, and was then turned upside-down by Stevens and Parrish’s (1999) seminal paper in Science: two and a half pages that transformed the way the world looked at sauropods.
John Martin looked at the cervical vertebrae of the Rutland specimen of Cetiosaurus oxoniensis, and concluded that the joints between them couldn’t be as flexible as people thought. He reconstructed that animal’s neck in a low, near-horizontal pose, and with a very narrow range of movement that didn’t allow it to raise its head far above shoulder level. Stevens and Parrish brought more rigour to this approach by modelling the cervical articulations of two sauropods (Diplodocus carnegii and Apatosaurus lousiae) using a computer program of their own devising, DinoMorph. And as most SV-POW! regulars will probably know, they got results similar to Martin’s, showing neutral positions for both animals that were well below horizontal, and finding restricted ranges of motion. (“neutral pose” here means that the vertebra are aligned such that the zygapophyses overlap as much as possible.)The DinoMorph posture was quickly adopted as orthodox, and got a lot of exposure in the BBC’s classic CGIumentary, Walking With Dinosaurs: episode 2, Time of the Titans, was primarily about Diplodocus, and under Stevens’s consultancy showed them as having obligate low posture throughout the show.
The new horizontal-neck orthodoxy was also reinforced by an exhibition at the American Museum of Natural History featuring a physical metal sculpture of a DinoMorph model:
This brings us pretty much up to date: there’s been very little in the way of published dissent between 1999 and now, and a couple more Stevens and Parrish papers have reinforced their contention. Upchurch (2000) published a half-page response to the DinoMorph paper, and Andreas Christian has put out a sequence of papers arguing for an erect neck posture in Brachiosaurus brancai on the basis that this best equalises stress along the intervertebral joints (e.g. Christian and Dzemski 2007), but otherwise all dissent from the DinoMorph posture has been limited to unpublished venues: for example, Greg Paul has posted several messages on the Dinosaur Mailing List disputing the low-necked posture, but has yet to put any of his arguments in print.
But enough of this dinosaury stuff. Let’s look at a nice, cuddly bunny:
Now here’s the thing: you wouldn’t guess by looking at it, but that rabbit has a vertical neck. In fact, it’s more than vertical: it’s so upright that it bends back on itself. Don’t believe me? Then take a look at this X-ray of an unrestrained awake rabbit:
Can it be that rabbits have unusual cervical vertebrae, such that when you articulate them in neutral pose they curve strongly upwards? No: and to prove it, here is (ahem) Taylor, Wedel and Naish (2009: fig. 1):
(Yes, this is a hare rather than a rabbit, but it’s close enough for government work.) What we found was that it was only possible to get the cervical skeleton anywhere near the habitual life posture by cranking all the proximal cervical joints up as far as they could physically go. In fact, it seems that some of the joints in the live animal flex more than the dry bones can — presumably due to intervertebral cartilage moving the centra further apart.
And this is fully in accord with the findings of Vidal et al. (1986), who X-rayed a selection of live animals (human, monkey, cat, rabbit, rat, guinea pig, chicken, monitor lizard, frog) and found that the neck is inclined in all but the frog. Furthermore, in all the mammals and reptiles, they found that:
- the cervical column is elevated nearly to the vertical during normal functioning;
- the middle part of the neck is habitually held relatively rigid;
- the neck is maximally extended at the cervico-dorsal junction and maximally flexed at the cranio-cervical junction; and
- it is the cranio-cervical and cervico-dorsal junctions that are primarily involved in raising and lowering the head and neck.
(In life, these facts are obscured from view by soft tissue.)
We also looked at unpublished live-alligator X-rays (thanks to Leon Claessens for access to these) and found that even in these ectothermic sprawlers, the neck is habitually elevated above neutral pose. Published X-rays of turtles and even (slightly) salamanders also showed the same tendency.
So what does this mean for sauropods? Simply, unless they were different from all extant terrestrial amniotes, they did not habitually hold their necks in neutral position, but raised well above horizontal. And if they resembled their closest relatives, the birds — and the only other homeothermic and erect-legged group, the mammals — then their necks were strongly inclined. As in, all the proximal cervicals were habitually cranked into the most erect positions they could attain. Kind of like this:
Which is a looong way form the DinoMorph posture that we were all getting used to but couldn’t learn to love. What do you know? Turns out that Osborn and Mook, and Janensch, were right after all.
So that, in a nutshell, is the contention of the first SV-POW! paper: that sauropods held their heads up high. That’s not to say that they couldn’t bring them lower when they wanted to — of course they could, otherwise they’d have been unable to drink — but we believe the evidence from extant animals says that they spent the bulk of their time with their heads held high.
I leave you with this rather beautiful piece that noted pterosaurophile Mark Witton drew to illustrate our favoured posture. Enjoy!
Stay tuned for more on neck posture …
For more cool stuff about the paper, including blog and media coverage and the chance to hear Mike on BBC Radio(!), see our page about the paper on the sidebar.
- Christian, A. and Dzemski, G. 2007. Reconstruction of the cervical skeleton posture of Brachiosaurus brancai Janensch, 1914 by an analysis of the intervertebral stress along the neck and a comparison with the results of different approaches. Fossil Record 10: 38-49.
- Janensch, W. 1950b. Die Skelettrekonstruktion von Brachiosaurus brancai. Palaeontographica (Supplement 7): 97-103.
- Martin, J. 1987. Mobility and feeding of Cetiosaurus (Saurischia, Sauropoda) why the long neck? In: P.J. Currie and E.H. Koster (eds.), Fourth Sympo- sium on Mesozoic Terrestrial Ecosystems, Short Papers, 154-159. Box- tree Books, Drumheller, Alberta.
- Osborn, H.F. and Mook, C.C. 1921. Camarasaurus, Amphicoelias, and other sauropods of Cope. Memoirs of the American Museum of Natural History, new series 3: 246-387.
- Paul, G.S. 1988. The brachiosaur giants of the Morrison and Tendaguru with a description of a new subgenus, Giraffatitan, and a comparison of the world’s largest dinosaurs. Hunteria 2 (3): 1-14.
- Stevens, K.A. and Parrish, J.M. 1999. Neck posture and feeding habits of two Jurassic sauropod dinosaurs. Science 284: 798-800. [Free subscription required]
- 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.
- Upchurch, P. 2000. Neck posture of sauropod dinosaurs. Science 287: 547b.
- 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.
March 31, 2009
Today saw the publication of the most startlingly dull paper I’ve ever been involved in (Upchurch et al. 2009) — and remember, I write this as co-author of a paper on the phylogenetic taxonomy of Diplodocoidea. Not only that, but one time when I was practising a conference talk with my wife Fiona as audience, she fell asleep actually while I was speaking. Actually asleep. And yet the new paper beats them all hands-down for boredom. If you don’t believe me, feast your eyes, gloat your soul, on the accursed ugliness of the very title of the new paper: “Case 3472: Cetiosaurus Owen, 1841 (Dinosauria, Sauropoda): proposed conservation of usage by designation of Cetiosaurus oxoniensis Phillips, 1871 as the type species.” What is it all about?
Well, take a look at the type material of Cetiosaurus:
Yes indeed — the most historically important of all sauropods is based on a set of non-diagnostic uninformative eroded partial mid-to-distal caudal centra. That is because this is the type material of the species which, for complex technical reasons, is the type species of the genus Cetiosaurus. We tend to ignore this fact because the material is clearly rubbish: the taxon C. medius is not valid. Sadly, however, the name C. medius is valid — nomenclaturally valid, even though it’s not taxonomically valid. But the International Code of Zoological Nomenclature (ICZN), which governs all zoological nomenclature, is purely a code of nomenclature, and does not take taxonomic considerations such as diagnosability into account. (It can’t, after all: how could the code contain rigorous rules that let you determine whether material is diagnostic, or whether a description is adequate?)
Anyway, the material of C. brevis, C. brachyurus, C. medius and C. longus, all published together (Owen 1842) is all pretty useless; but Phillips (1871) described in detail the much better material of a new species C. oxoniensis, and this is what everyone has meant by the name Cetiosaurus ever since. Upchurch and Martin (2003:215) even explicitly stated that they were provisionally using C. oxoniensis as the de facto type speces, pending a petition to the ICZN to overrule strict priority. And no wonder: the C. oxoniensis material really is way better. For example, check out this dorsal vertebra (which is by no means the best one — just one that I have a convenient photo of):
Today’s new paper is that long-promised petition: in it, we recount the nomenclatural history of the name Cetiosaurus and its species, explain with a big list of references that C. oxoniensis has been overwhemingly used historically and is overwhelmingly used today, and ask the Commission to legitimise this universal behaviour.
Will they do it? We actually don’t know, although I can’t think of any reason why they shouldn’t. The process now is that interested workers can send their comments, either in favour of or against our proposal, to the Executive Secretary of the ICZN (address at the end of the PDF), and these comments are weighed before a decision is returned. From my informal sampling of previous petitions, the process seems to take between one and two years. So we’re probably stuck in type-species limbo until 2011. Oh well — at least the main step has been taken.
So. I’m not exactly as excited about this paper as I was of Xenoposeidon — don’t worry, we won’t be launching a nine-post Cetiosaurus Type Species Redesignation Week — nor as pleased with it as I am with a certain in-press paper that all three of us SV-POW!sketeers are very much looking forward to because REDACTED. But it’s a dirty job that someone had to do.
- Owen, Richard. 1841. A description of a portion of the skeleton of the Cetiosaurus, a gigantic extinct saurian reptile occurring in the oolitic formations of different portions of England. Proceedings of the Geological Society of London 3: 457-462.
- Owen, Richard. 1842b. Report on British fossil reptiles, Part II. Reports of the British Association for the Advancement of Science 11: 60-204.
- Phillips, John. 1871. Geology of Oxford and the valley of the Thames. Clarendon Press, Oxford.
- Upchurch, Paul, and John Martin. 2003. The anatomy and taxonomy of Cetiosaurus (Saurischia, Sauropoda) from the Middle Jurassic of England. Journal of Vertebrate Paleontology 23: 208-231.
- Upchurch, Paul, John Martin, and Michael P. Taylor. 2009. Case 3472: Cetiosaurus Owen, 1841 (Dinosauria, Sauropoda): proposed conservation of usage by designation of Cetiosaurus oxoniensis Phillips, 1871 as the type species. Bulletin of Zoological Nomenclature 66 (1): 51-55.
Update (3 April 2009)
Here’s that photograph of a leopard seal pulling the head right off a penguin you ordered:
Acknowledgement: I got this photo from http://img238.imageshack.us/img238/873/1627.jpg. Thanks to “Paul A.” (see comment below) I now know that it is the work of Paul Nicklen who has a stellar collection of photographs on his own site. This picture is entitled The Death Shake, and is the 10th of the 29 pictures in his leopard seal gallery.
Relevant Update (31 August 2010)
I should have noted this long ago, but back in July 2009 (more than a year ago!) Paul Barrett and Pete Galton both published comments in the BZN that were supportive of our petition.