I recently stumbled across this rather good photograph of the holotype vertebra of our old buddy “Ultrasauros“, thanks to Wikipedia contributor Ninjatacoshell, and thought you’d like to see it:

This is a rather legendary vertebra, but until recently there were no good photographs of it on the web (I know because I tried to find one for my talk at the Dinosaurs: A Historical Perspective conference in 2008).

See It’s Ultrasaurus… I mean, um, Ultrasauros… err, Supersaurus! for the now-traditional run-down of the taxonomic mess surrounding this specimen.

In other news, everyone in palaeontology should read Heinrich Mallison’s recent article No 4WD For Plateosaurus over on the Palaeontologia Electronica blog.  He highlights a lot of important issues that have general applicability.

Over at his truly unique blog Paleo Errata, Jeff Martz is claiming that Stereopairs Are Cool. This assertion he supports with the following figure that he put together, showing a set of five stereopairs of a Longosuchus braincase:

Unfortunately, I am one of those who can’t “see” stereopairs, so these images are uninformative to me — or, at least, no more informative than your average inch-wide braincase photo.

So how else can we envisage the stereo information in these pairs of photos that Jeff took?  My favourite way is using red-cyan anaglyphs — those goofy 3d images that you look at through 3d glasses.  To compare, I did this to Jeff’s image.  The process is simple: take two copies of the stereopair image, cut out all the right-eye views from one set and all the left-eye views from the other, then edit the colour levels of both layers.  In one, take the red right down to zero, so you only have blue+green=cyan; in the other take the green and blue down so you only have red.  Then stack one layer on top of the other and change its mode to “Lighten only”.  Export the result as a JPEG and you get this result:

Armed with my red-cyan glasses (which, remember, I got as a freebie with a Lego catalogue), I can now make out the 3d structure really easily.  Positives for the anaglyph approach:

  • The 3D image is much easier to see
  • The result takes up less space on the page
  • Most importantly, the size limitation is removed: I have some beautiful whole-screen anaglyphs (e.g. Archbishop cervical, wallaby skull), whereas stereograms are restricted to a couple of inches’ separation.

The downside is, of course, that you need special equipment to see them –albeit equipment so laughably minimal that Amazon.com will sell you THREE PAIRS for $1.39, you cheap gits.  But for those of who who are too poor to find $1.39, and who don’t have two friends with whom you can form an ad-hoc 3D-glasses buying consortium at a cost of $0.47 each, there is one further approach: a low-rent technique that I call a “wigglegram” for want of a better term.  Here it is:

I discovered this approach by accident, when flipping through a bunch of photographs that I’d taken of, I think, the Archbishop.  As a matter of policy, I take most of my photos twice, so that if I shake slightly or the auto exposure gets it wrong, I have a good copy that I can retain.  I was trying to decide which of two nearly identical pictures to keep.  But as it happened, I’d moved the camera slightly to the side between taking the first and the second, so as I skipped back and forth between them, I was seeing two slightly different perspectives.

So there you have it: three different ways to visualise 3d structure, each built from the same basic set of photos.  They each have their merits, and I hope we’ll increasingly see more of all three of them, as we move into the Shiny Digital Future, and arbitrary limits on manuscript length and numbers of figures get lifted.

I leave y0u with an actual application of all this.  Matt and I have, for some time, been working on a manuscript about caudal pneumaticity in sauropods, and we wanted to include a brief survey of which genera it’s been reported in.  Among the candidates was Saltasaurus, which has a candidate pneumatic caudal vertebra that was illustrated thus by Powell (2003: plate 53, part 3):

Matt can “see” stereograms, and insisted that the dark patch on the side of the centrum is a pneumatic fossa.  I wasn’t so sure, and in fact we got into quite an argument over whether or not to include this specimen in our list.  The argument was neatly concluded when I had the obvious idea of converting Powell’s stereogram into an anaglyph:

As soon as I saw this, I recognised what the structure is: the crescent moon-shaped dark patch is indeed a deep, invasive fossa, and the broad, roughly circular object above it and to the right is a lumpen lateral process sticking right out into the camera (and partially hiding the fossa).  So Matt was right, the vertebra is pneumatic, and a beautiful friendship was saved by the power of red-cyan anaglyphys.  Yay!

References

  • Powell, Jaime E.  2003.  Revision of South American Titanosaurid dinosaurs: palaeobiological, palaeobiogeographical and phylogenetic aspects.  Records of the Queen Victoria Museum 111: 1-94.

Pimp my ‘pod 2: haids

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].

After seeing one of the preliminary designs for the documentary Sauroposeidon–which sadly ended up being a Big Gray Pachyderm in the show–I sent the following. Even though they ignored it, and even though it appears here as a rehash of an argument I’ve made several times already, I’m still proud of it. Especially the concluding advice–potential artistic collaborators take note!
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.

Pimp my ‘pod

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.

Follow

Get every new post delivered to your Inbox.

Join 396 other followers