August 22, 2012
No time for anything new, so here’s a post built from parts of other, older posts.
The fourth sacral centrum of Haplocanthosaurus CM 879, in left and right lateral view. This is part of the original color version of Wedel (2009: figure 8), from this page. (Yes, I know I need to get around to posting the full-color versions of those figures. It’s on my To Do list.)
Note the big invasive fossa on the right side of the centrum. The left side is waisted (narrower at the middle than the ends) like most vertebrae of most animals, but has no distinct fossa on lateral face of the centrum. What’s up with that? Here’s an explanation from an old post (about another sauropod) that still fits:
Now, this asymmetry is also weird, but it’s expected weirdness. Pneumaticity seems to just be inherently variable, whether we’re talking about human sinuses or the facial air sacs of whales or the vertebrae of chickens. It appears that the form of pneumatic features is entirely determined by local tissue interactions, with little or no genetic control of the specific form. Think of it this way: genes prescribe certain developmental events, and those events bring tissues into contact–such as pneumatic epithelium and bone. The morphology of the bone arises out of that interaction, and each interaction of bone and pneumatic epithelium has the potential to produce something new. In this case, the diverticula on the left side of the vertebral column come from the lungs or air sacs on the left, and those on the right side come from the lungs or airs sacs on the right, so it’s really two sets of diverticula contacting the bone independently. The wonder, then, is not that pneumatic bones are so variable, but that we see any regularities at all.
January 14, 2011
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.
April 28, 2010
This one’s mostly a housekeeping post, to keep you abreast of some notable developments with SV-POW!sketeers and friends.
- Added April 29 – I’m such a tool, forgot to mention that another awesomely niche-y blog has been unleashed on the paleo-blogosphere: March of the Fossil Penguins, by our friend and sometime sauropod-describer Dan Ksepka. Go waggle your hydrodynamic forelimbs at him, I’m sure he’ll be happy to regurgitate some tasty posts for you.
- I’m tired of paying for sauroposeidon.net so I’m letting it lapse at the end of this week. I’ve already migrated my CV and papers to a new site, where they will hopefully remain forever. As previously noted, The Marsh Repository also has a new home.
- Ask A Biologist is back! Go make yourselves useful/satisfy your curiosity. Don’t forget to thank your friendly local Dave Hone.
- Mike’s new blog, The Reinvigorated Programmer, is all of two months old and has already passed SV-POW! in total hits. So don’t give him any more link traffic. Instead, tell your friends how wonderful SV-POW! is!
- After two and a half years of weekly posts, we’ve decided to stop being so slavish about our titular obligation and will henceforth blog as frequently or infrequently as we please. We’re keeping the title, though. If you’re offended by that, you can backronym SV-POW! as Sauropod Vertebra Picture of the Whenever.
- Similarly, we’re going to start posting about sauropod skulls and appendicular bits from time to time. Not that we haven’t been doing that anyway–heck, even wallaby toes are not safe from our roving curiosity–but we’re going to stop marking such posts off-topic and putting in obligatory sauropod vert photos.
Don’t worry, though, we’ll still be mostly sauropod vertebrae, most of the time. And speaking of, here’s something lovely: a cervical of Rapetosaurus, from Curry Rogers (2009:fig. 5). Cool fossae, eh? Also, check out how dinky the centrum is compared to the neural arch.
Curry Rogers, K. 2009. The postcranial osteology of Rapetosaurus krausei (Sauropoda: Titanosauria) from the Late Cretaceous of Madagascar. Journal of Vertebrate Paleontology 29(4):1046-1086.
September 25, 2009
I made brachiosaur sand-sculptures.
(And yes, it’s that Daniel Taylor, the author of Taylor 2005 — a copy of which apparently hangs on the wall of the Padian Lab.)
But wait! Is the brachiosaur truly asleep, as it seems, or is it actually the victim of a mighty hunter?
No, it turns out it was just asleep after all; and I joined it.
… and finally: your obligatory sauropod-vertebra shot:
January 13, 2009
Just got back my supervisor’s comments on my draft dissertation front-matter. Looks like I’m not going to be able to go with my chosen title.
Here is another of my supervisor’s corrections to my draft dissertation, this in the part of the acknowledgements that mentions Darren:
(For anyone who doesn’t get the reference, see this post at Tetrapod Zoology.)
Matt won’t let me get away with a post that doesn’t include a sauropod vertebra, so here is BMNH R173b, a Mystery Sauropod Cervical of the Wealden, in right lateral view:It’s not in super-great shape, but this about as good as Wealden cervicals get: for some reason, dorsals seem to fare better in the preservation stakes. I’m not going to attempt even the most tentative ID for this.
The thing to look out for here is the absolutely honking huge cervical rib. In, well, every other sauropod cervical in existence, the cervical ribs quickly taper as they extend backwards from the diapophysis and parapophysis, but this does no such thing: it seems to have a big, fat club on the end of it. The next time I’m down in the NHM collections I need to have a careful look at this and check that someone hasn’t attached a chunk of tibia or something — but if this is legit, then what we have here is the one sauropod element I’ve ever seen for which Martin et al.’s (1998) ventral bracing hypothesis might just work. (Although actually it wouldn’t, for other reasons which I won’t discuss now.)
November 15, 2008
Happy Xenoposeidon day! Today, November 15, 2008, is the one-year anniversary of the publication of Xenoposeidon Taylor and Naish 2007.
By happy coincidence, I’ve just been sent a courtesy copy of Kids Only, a new guide-book for the Natural History Museum … and there is Xenoposeidon on page 5, exemplifying dinosaur diversity. Rock!
It’s good to see our baby out there educating people!
For much more of Xeno, see Xenoposeidon week.
September 23, 2008
Internal structure of a cervical vertebra of Sauroposeidon, OMNH 53062. A, parts of two vertebrae from the middle of the neck. The field crew that dug up the bones cut though one of them to divide the specimen into manageable pieces. B, cross section of C6 at the level of the break, traced from a CT image and photographs of the broken end. The left side of the specimen was facing up in the field and the bone on that side is badly weathered. Over most of the broken surface the internal structure is covered by plaster or too damaged to trace, but it is cleanly exposed on the upper right side (outlined). C, the internal structure of that part of the vertebra, traced from a photograph. The arrows indicate the thickness of the bone at several points, as measured with a pair of digital calipers. The camellae are filled with sandstone.
Addendum (from Mike)
What Matt’s failed to mention is that this section of prezygapophyseal ramus is one of the elements for which he calculated the Air-Space Proportion (ASP) in his chapter in “The Sauropods”. As shown in his table 7.2, this calculation yielded 0.89. Just think about that for a moment. 89% of the bone was air. Yikes.
It’s interesting that this was the only prezygpapophyseal ramus in the survey, and that it had a way higher value that any of the other elements considered, which topped out at 0.77, i.e., more than twice as much bone as this specimen. So maybe all prezyg rami are ridiculously pneumatic? So far (as far as I know) no-one’s measured the ASP of another ramus, so the answer remains, for now, ridiculously unknown to our planet.
Special bonus weirdness
Basal sauropodomorph wizard Adam Yates has posted an entry on his blog showing more sauropod vertebrae/ceratopsian frill convergence, as follow-up to our own recent post. Too weird.
September 10, 2008
The remarkable object shown here (the one on the left) is a copy of the famous BYU 9044 bone. I know you’ve all heard the story a million times before: it’s the stuff of late-night parties, and fireside stories-from-grandpa, but it would be wrong not to recount it again. First described by Jensen (1985) as the holotype of the new brachiosaurid Ultrasaurus macintoshi (a name that was later changed to Ultrasauros macintoshi), it was much later shown – by Curtice et al. (1996) – to belong not to a brachiosaur, but to a diplodocid. Furthermore, because it was found literally among the bones of the holotype of the diplodocid Supersaurus vivianae, the most logical course of action was to, alas, sink Ultrasauros into Supersaurus… and hence Ultrasauros was no more.
Jensen (1985) figured the vertebra in right lateral view, so the left-hand view you’re getting here is the sort of thing that has sauropod vertebra fans swooning and lying awake at night. There is, of course, a ton of neat anatomy to talk about here.. but I don’t have time to talk about it. You will no doubt have been impressed by the size: the scale is kindly provided by Sam Heads of Palaeoentemology and Insect Evolution.
Curtice, B., Stadtman, K. L. & Curtice, L. J. 1996. A reassessment of Ultrasauros macintoshi (Jensen, 1985). In Morales, M. (ed) The Continental Jurassic. Museum of Northern Arizona Bulletin 60, 87-95.
Jensen, J. A. 1985. Three new sauropod dinosaurs from the Upper Jurassic of Colorado. Great Basin Naturalist 45, 697-709.
Special Bonus: Non-Sauropod Saurischian Vertebra Picture Of The Week!
Hi, Mike here. It’s a bit rude to tag onto the end of Darren’s post, but I don’t want to make a brand new post and shove Ultrasaurus, er, Ultrasauros off the front-page. Anyway, I’ve made available my close-up photos of a turkey cervical. Click through the image for details. Enjoy!
August 28, 2008
When we were planning to start this blog, Matt wrote to Darren and me saying “I am thinking that we should keep the text short and sweet” — an aspiration that we have consistently failed to live up to. Not today!
Here is Omeisaurus tianfuensis. Even by sauropod standards, that neck is just plain crazy.
This figure is lifted from an awesomely comprehensive monograph — 173 pages including the front-matter and plates — which gives the lie to the idea that all Chinese dinosaurs are woefully inadequately described. It’s true that with the recent glut of theropods, the thing seems to be to rip ‘em out of the ground, throw toegther a two-pager for Science or Nature and move on to the next one; but sauropods understandably inspire more devotion from their followers, resulting in careful work like this monograph and the similar work by Ouyang and Ye (2002) on Mamenchisaurus youngi. So hats off to He, Ouyang and their colleagues — showing how it should be done!
Special bonus photo
- He, X., K. Li, and K. Cai. 1988. The Middle Jurassic dinosaur fauna from Dashanpu, Zigong, Sichuan, vol. IV: sauropod dinosaurs (2): Omeisaurus tianfuensis. Sichuan Publishing House of Science and Technology, Chengdu, China. 143 + 20 plates pp.
- Ouyang, H., and Y. Ye. 2002. The first mamenchisaurian skeleton with complete skull: Mamenchisaurus youngi. Sichuan Science and Technology Press, Chengdu, China. 111 + 20 plates pp.