Here comes Santaposeidon!



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.

Happy Christmas from Mike Taylor and brachiosauridae incertae sedis BMNH R5937, "The Archbishop", coalesced dorsal vertebrae 8-9 (in right lateral view, like you need me to tell you that). Image in part copyright (C) the Natural History Museum, but it's the season of goodwill so they probably won't sue you even if you send copies to all your friends.

Things to Make and Do, part 3: Butchering a Wallaby

This is part 3 of an emerging and occasional SV-POW! series: part 1 was the pig skull, and part 2 was the lizard feet (though not advertised as such because I couldn’t resist the sauropod pun).

Bennett's wallaby, right lateral view

Today, we’re going to be taking a wallaby apart.  Specifically, a Bennett’s wallaby, the larger of the two subspecies of the red-necked wallaby Macropus rufogriseus.  I was delighted (though of course also saddened) to get a call on Saturday afternoon from the very same mini-zoo that had given me Charlie the monitor — Dick Whittington Farm Park in Longhope, Gloucestershire.  They have a small group of seven wallabies sharing a paddock with goats, and one had died — most likely from being butted by one of the goats, although there were no external signs of injury.

This is going to be the largest animal I’ve prepared the skeleton out of — I measured it at 123 cm from snout to tail and 10.5 kg total weight, which compares with 75 cm and 12 kg for the badger, 100 cm and 5.2 kg for the fox and 111 cm and 3.4 kg for the monitor.  Yes, the badger was heavier, but the awkward shape of the wallaby makes it all-round “bigger” and harder to deal with.  Both the badger and the fox would, just, fit into large plastic toy-boxes which I buried and will exhume after a suitable time has passed, but that wasn’t going to work for the wallaby.  I needed to take that baby apart:

Bennett's wallaby, right ventrolateral view into guts

I was pleasantly surprised at what good condition the guts were in (compared with the horrible state of Charlie innards) — nice and fresh.  If I’d had time, I’d have attempted to learn something from a proper dissection, but as I was pushed for time (trying to get this done in my lunch break) I had to push on.  I discarded the guts and started to carve up the remainder.

Bennett's wallaby in posteroventral view. right leg removed; Homo sapiens for scale

The knife is a Norwegian fisherman’s knife — very sharp, and short enough to be easy to wield.  It’s perfect for dismembering a carcass this size, even though previously I’ve only used it for slicing sushi rolls.  It was a Christmas present from my employer, Index Data, a few years ago.

My plan was to carefully divide the animal into seven portions (head, torso, tail and four legs), remove as much skin and muscle as I could without risking damage to the bone, and to process the parts separately.

Bennett's wallaby, in kit form, mostly dorsal view but with the head and torso in left lateral. WARNING: GRAPHIC CONTENT

After some thought, I decided to prepare the skull and the left fore- and hind-limb by boiling, and to bury the rest in the box.  Here are the relevant divisions:

Bennet's wallaby not looking at all healthy. Top: torso, tail and right fore- and hindlimbs, awaiting burial. Bottom left: head, left fore- and hindlimbs, awaiting cooking. Bottom right: bag full of discarded soft-tissue

Then I put the pot through an hour’s simmering, peeled the skin off the skull and feet, and removed what meat I could; then I simmered a second time and removed more meat.  By this stage, I was able to remove the three most anterior cervicals, which had been attached to the back of the skull — but they are still so covered with attached flesh that they’re not much use yet.  Here’s how the simmered material is looking:

Bennett's wallaby: skull, anterior cervical vertebrae and left hind-limb long bones

And here is the skull as it looks now, after a little more flesh-picking (but not nearly enough):

Bennett's wallaby, partially prepared skull in right lateral view

I think that it (and the other boiled bones pictures above) would benefit from a third simmer-and-pick session before I put them out somewhere for invertebrates to deal with.  While that’s going on, I’ll prep out the foot and the forelimb, which have also been boiled twice but phalanges are a right nasty piece of work.

And then I have to decide what to do with my big yellow box that has the rest of the bits in.  Plan A is still burying, but it is kind of tempting to simmer these parts, too, and get the whole thing completed much more quickly.

On the other hand, now is not a good time for such an effort: I will be away from home all week on a mission of utmost importance, and of great relevance to this blog.  Details to follow!

Finally, I leave you with your weekly sauropod-vertebra goodness!

Giraffatitan brancai paralectotype HMN SI, cervical vertebrae 2 and 3 in right lateral view, attempting to do DinoMorph

Things to Make and Do, part 1: Pig Skull (off-topic)

I know, I know: a pig skull is not a vertebra, and it’s not from a sauropod. On the other hand, it is a cool zoological object, and every home should have one. I’m going to show you, in glorious technicolour, how I made a pig skull in under 24 hours at a cost of £3 and some silver, using only implements I had lying around.

First, here is the finished article, just so you know where we’re headed:

Pig skull, cleaned and complete

To get there was a four-step process, which I was comfortably able to do in an afternoon and early evening.  It all started as we were driving the boys back from swimming on the Saturday morning, and I stopped in a butcher’s shop in Cinderford to ask whether they had any complete heads.  I got a hit straight away: they had a 20 lb pig’s head which they costed at 25p per pound for a total of £5.  I ummed and ahed a bit, not because of the price but just because the thing was so darned big; while I was hesitating, the butcher said that, all right, he’d cut off the huge slabs of neck-fat and get the price down to £3.  Great: apart from anything else, that made the head portable.  So the deal was done, and I brought the only-slightly-mutilated head back home.  Here it is on our patio:

Pig's head, pretty much whole and complete

Now for the preparation, you need:

• A sharp knife
• A big cooking pot
• A teaspoon
• A Japanese-style chopstick (see below)
• A toothbrush that you don’t plan on ever using again
• An understanding spouse

About the chopstick: you want it to have a fairly pointed end so that you can go poking it in cracks and crevices, so a Chinese-style broad-tipped chopstick won’t do at all.  If you don’t have a Japanese-style chopstick, simply visit a sushi restaurant and take the sticks home with you at the end of the meal.

Got your tools?  OK, off we go!

Stage 1: defleshing

First, cut off all the excess soft-tissue that surrounds the skull.  One reason is just to get rid of it up front so you don’t have to cook it off, but the main reason for me was just to get the head small enough to go in the pot — pig’s heads are big things.  You do need a good knife for this, strong and sharp, and a strong stomach.  At first it felt pretty icky to be slicing bits off a head, but before long I was sawing away merrily at the lips and I guess all told it took about twenty minutes to reach this stage:

Pig head, defleshed

In case it’s not completely clear, that is the head slightly to right of centre — you can see its teeth if you look carefully.  To the left is the huge pile of fat that I’d sliced off the head.  I could not believe what fat heads pigs have.  The amount of actual meat is tiny in comparison: you can see it over on the right.  Most of this was little fragments, with the only two half-decent chunks being from the cheeks.  I guess they were about two ounces of meat each (50 g), based on the similarity in size to a vanilla McDonalds hamburger.

Stage 2: boiling

At this point, I threw away the fat, put the head in the pan, filled the pan with freshly boiled water until it covered the head, added some washing-up liquid (“dish soap” for you Americans) and left it to simmer for two hours.  While that was happening, I fried the meat from Stage 1 and ate it as part of my lunch.  Danny (my eldest son) had some; the other two didn’t fancy it.

After two hours, I poured away the hot water, filled the pan with cold water to cool the head, then took it out and started pulling off all the soft tissue.  Two hours in the pot had made a big difference, and big slabs of gristle came away neatly from bone.  Once I was done, the head looked like this:

Pig's head, boiled and stripped

Notice the big pile of meat to the right — that’s what came off at this stage.  By now the shape of the skull is apparent, but there is still plenty of soft-tissue left.  In particular, the big jaw muscles inside the zygomatic arches were impossible to get out at this stage, thanks to a combination of strength and slipperiness.  At this stage, the lower jaw could, just, be moved, whereas before it was solid with rigor mortis.

If I were making a movie about zombie pigs, this is the stage I’d film them at.

I took this photo before removing the eyeballs (this is where you need the teaspoon).  Turns out that eyeballs are a lot tougher than I’d realised; so are the optic nerves.

Stage 3: reboiling

At this point I didn’t know how many boilings would be needed, but it turns out that the next one was the last.  Into the pot it went again, with fresh hot water and washing-up liquid, for another two-hour simmer.  When it came out, I drained and cooled it as before, and picked off as much of the remaining flesh as I could.  Now the jaw muscles came away easily, and I was able to pull out the cartilage plug in the nose.

Pig's head, reboiled and stripped

Again, there was a surprising amount of meat from this stage, but the skull was basically free of its fleshy encumbrance by this point.  I rather wish now that I’d kept the fat from stage 1 and the meat from stages 2 and 3 so I could have piled it all up together and photographed it together with the skull.

By now, the mandible was cleanly separated from the cranium, and it was easy to rub away the remains of the cartilage covering the joint.

Stage 4: cleaning

By now, only small and tough bits of meat remained.  Plenty of them could be scraped away using the Japanese chopstick: this was particularly useful for digging around in between the teeth.  By far the hardest part of the cleaning, though, was getting rid of the brain and the cranial nerves.  The problem is of course that you don’t want to crack the braincase open, and the brain is far too big to come out of the foramen magnum.  Apparently the only way to do this is to swirl your chopstick around inside the braincase, then try to scrape the brain out bit by bit.  This I did using several methods: I poked the cranial nerves back inside the braincase with my trusty sushi stick, smushed everything up, tried to hook bits out, ran water through the skull from nose to braincase and generally shook that baby around, getting little bits of brain out.  This took a while and was, truthfully, not the most delightful time of my life.

But it was well worth it, because by the time I’d done, the skull looked like it does in the photo at the top of this post.  And here is a more scientific composite, showing the cranium in five cardinal views:

Pig cranium in dorsal view (top row); posterior, right lateral and anterior views (middle row); and ventral (bottom row).

This image, together with versions on white and grey backgrounds, is also available over on my website, next door to the turkey cervical.

Folks, a pig skull is a serious piece of kit.  What I have here is the foundations of my very own museum of comparative osteology.  Everyone ought to make one.

So am I done?  Not quite — there is still …

Stage 5: final cleaning

There are a few bits and pieces of meat that I couldn’t get at, either because they were too firmly attached, tucked away in narrow crevices, or inside the braincase where I couldn’t see what I was doing.  So it’s time to let invertebrates do their bit.  The skull is currently out in the garden, under a bucket weighed down with bricks so a fox doesn’t wander off with it.  Hopefully in a few weeks, insects will have dealt with the remaining soft-tissue.  Then I can re-bleach the skull in dilute hydrogen peroxide to deal with the likely discoloration, and glue the loose teeth into the defleshed sockets, and then I really am done.

I leave you with a photograph of my two eldest sons, Matthew (9) and Daniel (10), with the partly prepared specimen.

Left to right: Matthew, Piggy the Piggy from Piggyland, Daniel.

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Obligatory sauropod-vertebra picture

Sacrum of Camarasaurus supremus, AMNH 5761, in left posterolateral view.

What heads tell us about necks, redux

I Cannot Brain Today, I Have the Dumb

Man, I hate making mistakes. The only thing worse than making mistakes is making them in public, and the only thing worse than that is finding them in published papers when it’s too late to do anything about them. About the only consolation left–if you’re lucky–is getting to be the one to rat yourself out (we have to do this a lot). So here goes.

Neck angle FAIL

In our figure 4 (from Taylor et al. 2009) we showed the skulls of three sauropodomorphs, Massospondylus, Camarasaurus, and Diplodocus, posed with horizontal semicircular canals (HSCCs) level, angled 30 degrees above horizontal, and angled 20 degrees below horizontal, as it is written (by Duijm 1951). We also showed the angle of the occipital condyle when the HSCCs are level; if the craniocervical joint was in osteologically neutral pose (ONP), that line would indicate the angle of the anterior cervicals.

Trouble is, we put the neck lines for Diplodocus and Camarasaurus in the wrong places.

As any idiot can see from Sereno et al. (2008: fig 1), the brain, brainstem, and occipital condyle form a line that runs from roughly the upper part of the orbit (in lateral see-through view) out the back of the head. Now if you look at our fig. 4 you’ll see that the ONP lines for Camarasaurus and Diplodocus are much too inclined, so that if the brain was in line with the anterior neck–which it should be, in ONP–it would be sticking out the back of the head.

If that doesn’t make sense, just look at the above illustration, imagine the brain and spinal cord in a straight line parallel to the black neck line but also dorsal to it, and you’ll see that the brain would be outside the skull. Those incorrect neck lines don’t represent impossible postures, but they don’t represent ONP, either.

Taxonomic variation WIN!

Here’s a corrected up version of the figure to show what I mean. The black lines are still the ONP neck lines, and now I’ve put in shadowy necks at +30 and -20 to go with the shadowy heads. The 50 degree spans marked out by the shadowy necks are the ranges within which the neck could articulate in ONP with skulls stuck in the 50-degree “Duijm window”.

Caution: it is very easy to misread the shadowy necks as showing a range of movement within an individual; in fact, the neck lines are ‘anchored’ to the skulls in ONP as the skulls rotate through the 50 degrees allowed by the HSCCs. They are not individual movement but the possible range of taxonomic variation in HSCC orientation according to Duijm (1951).

Worth noting here is the likelihood that Massospondylus had a more elevated neck than any of the neosauropods studied so far–certainly a finding at odds with the traditional depictions of basal sauropodomorphs. (It is just a likelihood, though, since the top, neck-wise, of Massospondylus’s Duijm window overlaps with the windows of the other taxa a bit.)

Nigersaurus, buddy, why so down?

In this version I’ve gone one step farther and included Nigersaurus (modified from Sereno et al. (2008: fig 1). Nigersaurus differs from Diplodocus in the angle of the face from the HSCCs and occipital condyle, not in the angle between the HSCCs and the occipital condyle, which is remarkably similar in Camarasaurus, Diplodocus, and Nigersaurus. This suggests that Nigersaurus held its head differently than other sauropods, but not necessarily its neck.

Keep in mind, though, that the difference in facial angle between Diplodocus and Nigersaurus is less than 50 degrees, and that some of the head postures in the respective Duijm windows of the two taxa are identical. So we can’t say for certain that Nigersaurus held its head differently than Diplodocus; it is possible that they held their heads at the same angle and that Nigersaurus just carried its HSCCs at a different angle. If that were the case, the neck of Nigersaurus would have been more inclined than that of Diplodocus. I’m not arguing that that’s likely–it seems perfectly plausible that the two taxa might have held their necks similarly and their heads differently, as suggested above–I’m just pointing out the very wide range of possibilities allowed by the data. To reiterate one of the points of the paper, HSCCs aren’t useless for determining habitual head posture, they just can’t narrow things down very far on their own.

Also note that some of the neck postures allowed by the Duijm window have the anterior cervicals running down, below horizontal, not up. And many of the allowed neck postures for the neosauropods are close to horizontal. So, we were wrong and HSCCs + occipital condyles show that most sauropods held their necks close to level and not strongly elevated after all, right?

Onward and Upward, or Down in Flames?

Not so fast. Remember that all of the neck lines in the above figures show the angle of the anterior neck if the neck was in ONP with the skull. But Vidal et al. (1986) found that the skull is habitually flexed on the neck, even in lizards, and we have since verified this for salamanders, turtles, and more. And sometimes the flexion is dramatic.

Our figure 1 (from Taylor et al. 2009) shows the cranium, cervicals, and first few dorsals from a hare in ONP and in the posture shown by Vidal et al. (1986: fig. 4b). The difference between the anteriorly-directed ONP pose and the backward-leaning Vidal-compliant pose is striking. I measured the angle between the cervical column and the maxillary toothrow to be ~110 degrees in the ONP pose and ~70 degrees in the Vidal-compliant pose (try it yourself with Paint or Photoshop, or download some free image manipulation software). That means the head is flexed on the neck by 40 degrees! That is a big angle. If sauropods did the same, you could take the neck lines shown above and crank them down by 40 degrees (remember that the heads are “fixed” into the 50-degree Duijm windows allowed by the HSCCs), which would make Mike’s elevated Diplodocus look not just achievable, but perhaps even conservative.

Where does all that leave us? In sauropods for which HSCC orientation is known, putting the HSCCs level the anterior neck is still inclined, and even with the HSCCs angled 20 degrees down the ONP neck would only be slightly below horizontal, and if the head was Vidal-compliant (strongly flexed on the neck), the neck would have to be above horizontal. So heads still tell us about necks, and in particular they tell us that the necks angled up. Our neck lines for Camarasaurus and Diplodocus are not correct for ONP, but probably represent attainable postures. My first head ‘n necks post has the angles too exaggeraged for ONP, too, but again all of those poses are not just possible but likely if the head was flexed on the neck.

Miscellanea

We owe mad props to Brian Engh, a.k.a. The Historian, who burst on the paleo-rap scene with a rap video about crocodilian predation and almost certainly the first ever kung-fu rap video to name-check titanosaurs. Brian stumbled across Mike’s extra goodies page for the new paper about week before the paper was due out, and kindly suppressed the information until after D-Day. You can and should download his entire album, Earth Beasts Awaken (open access, yo), and kick it old school.

Congratulations to Francisco “Paco” Gasco, who just got funding for a PhD to do a complete morphological and paleobiological workup on the giant Spanish sauropod Turiasaurus. You’ll be hearing more about Paco in the not-too-distant future, we promise.

Finally, here’s that video of an elephant grabbing an ostrich by the neck that you ordered.

The End of the Beginning?

This brings us to the end of ten solid days of new posts, which is a new record for us and one not likely to be broken for a long time, if ever. We never planned to do all this; in the beginning we each were going to contribute one post and that would have been that. But we kept finding things that we felt needed to be discussed.

As all of us have been saying in every available medium, this is not the end of anything. The sauropod neck posture debate is not over; in a few years we may look back and see that in 2009 we were still stumbling to the real starting line. We don’t think this stuff is unimportant or unknowable, and we’re going to keep working on it, and we hope lots of others do as well.

We’ll see you out there.

Up, boy, up! Heyaaah!!

References

• Duijm, M. 1951. On the head posture in birds and its relation to some anatomical features. II. Proceedings of the Koninklijke Nederlandse Akademie van Wetenschappen, Series C 54: 260–271.
• Sereno, Paul C., Jeffrey A. Wilson, Lawrence M. Witmer, John A. Whitlock, Abdoulaye Maga, Oumarou Ide and Timothy A. Rowe.  2007. Structural Extremes in a Cretaceous Dinosaur. PLoS ONE 2 (11): e1230 (9 pages).  doi:10.1371/journal.pone.0001230
• 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.

What heads tell us about necks

So far in our coverage of the new paper (Taylor et al. 2009) we’ve mostly focused on necks, following the discovery by Graf, Vidal, and others that when they are alert and unrestrained, extant tetrapods hold their necks extended and their heads flexed. (Although they turn up with distressing regularity, “ventroflexed” is redundant and “dorsiflexed” is an oxymoron; Darren lays down the law here.)

There’s more to the paper; about half of our argument is primarily about heads and only secondarily about necks, and has to do with semicircular canals (SCCs). SCCs are sense organs in the inner ear that determine the orientation and acceleration of the head. Hagfish have a single loop on each side, lampreys have two loops per side, and gnathostomes (jawed vertebrates, like us) have three per ear, all set at right angles to each other to capture position and movement information in all directions no matter how the head is oriented. There’s a brief overview of how the system works here, and here’s what SCCs actually look like (in this case in the theropod dinosaur Ceratosaurus, from Sanders and Smith 2005:fig. 5):

SCCs are relevant to posture and locomotion: animals that move rapidly tend to have big canals, especially big anterior canals, and the horizontal semicircular canals (HSCCs) are usually held more or less level as animals go about their business. It’s the “more or less” part that gets sticky, as we’ll see in a minute. SCCs and inner ear anatomy in general are areas  of accelerating research in vertebrate paleontology, because the soft tissues that comprise them (the membranous labyrinth) are housed in dense bone (the bony labyrinth) which is often preserved and can be imaged non-invasively using CT. Even braincases that look pretty crappy from the outside can yield beautifully-preserved bony labyrinths, from which the dimensions of the membranous labyrinth can be measured and the acuity of the system can be estimated.

Where SCCs have really attracted attention in paleontology is the “more or less” horizontal orientation of the HSCCs in living animals. Some authors have argued that if you set the HSCCs level or close to level, you can figure out how the head was oriented in life.

Well, maybe. The problem is that there is a LOT of variation around level. In birds surveyed by Duijm (1951), HSCC orientation varied by 50 degrees among taxa, from 20 degrees below horizontal to 30 degrees above. Furthermore, in humans HSCC orientation varies by up to 20 degrees among individuals. Possibly humans are weirdly variable, but it seems at least equally likely that most critters are and we’ve only discovered that variation in humans because of the huge sample size.

However you slice it, those are darn big error bars around any given head posture. That doesn’t mean that HSCC orientations in dinosaurs and other extinct vertebrates are worthless for determining posture (they may also be a source of taxonomic information). Strictly speaking, it means that preserved HSCCs can get us in the 50-degree ballpark but can’t narrow things down any further. This is one of those areas in paleontology where we’re just going to have to live with a certain amount of uncertainty, at least for now.

We’re not done with heads, though. Once the HSCCs get us in that 50-degree range, we still have to figure out how the neck facilitated those postures. One thing that seems to hold across the board in sauropodomorphs is that when the HSCCs were in the -20 to +30 range around horizontal, the occipital condyles were pointed down. And that has major implications for the posture of the neck, as we’ll see in the following example.

Let’s start with this neatly abstract Apatosaurus skeleton, borrowed from Kent Stevens’s site here. Note that this version is from 2005 and Kent has updated his models considerably since then. I’m using this one because its elegant minimalism made it easy for me to play with, but it doesn’t represent Kent’s current thinking.

Here’s the same image with some lines drawn on to indicate the long axis of the skull, the orientation of the occipital condyle, and the angle of the anterior neck. In Apatosaurus and Diplodocus the occipital condyle is at right angles to the long axis of the skull. That means that if the cranio-cervical joint was held in “neutral pose”, the head would be at right angles to the anterior neck. Recall that extant tetrapods hold their heads flexed on their necks. This Apatosaurus has its head extended by 50 degrees. This is major extension–to see what it feels like, lean your head back until you’re looking straight up, and then lower your head until its almost halfway back to normal. Imagine walking around like that. In this pose the HSCCs are angled down, within the 50-degree ballpark but not level.

Just for the sake of argument, let’s set the HSCCs level and force the craniocervical joint into ONP. Now the head and first few cervicals are okay, but clearly this posture won’t work with the neck in the original pose. We’re going to have to move the neck up to meet the steep angle dictated by the HSCCs and the occipital condyle.

One option is to keep as much of the neck in the original pose as possible, and just elevate  the vertebrae closest to the head.  This is not so far off from how Apatosaurus has been depicted for more than a century. But it doesn’t agree with the data from extant tetrapods, in which the neck is extended at its base.

Here’s the partially Vidal-compliant version, with the cranio-cervical joint in ONP and the base of the neck extended. To be fully Vidal-compliant, the head would have to be flexed on the neck. In the diagram, that would have the effect of turning changing the angle between the long axis of the skull and the anterior cervicals from a right angle to an acute one. Since the orientation of the head is “fixed” by the semicircular canals (in this example), that means the neck would have to be even more steeply inclined.

One more for the road. Here the HSCCs are angled up by 20 degrees, which is in the upper part of the range but certainly not an extreme value for either birds or mammals; chances are you and your cat carry your HSCCs at about the same angle (intraspecific variation caveat applies!). Angling the HSCCs up moves the occipital condyle further down, which makes the neck steeper still.

You may look at that last picture and think it’s impossible or crazy, and I don’t blame you if you do.  Remember that all I’ve shown you is two possibilities from within the 50-degree ballpark defined by the HSCCs. But even if we put the HSCCs at the very bottom of that range, the occipital condyle still points down at something like 25 degrees below horizontal, which means the anterior neck has to be angled up at 25 degrees just to keep the cranio-cervical joint in ONP; if the head is flexed on the neck, it has to be steeper.

The moral of the story is that, even within the broad range of postures allowed by the HSCCs, head posture still constrains neck posture to be elevated in most if not all sauropods. It will be VERY interesting to see how the skull of Brachytrachelopan is put together, when one comes to light.

References

• Duijm, M. 1951. On the head posture in birds and its relation to some anatomical features. II. Proceedings of the Koninklijke Nederlandse Akademie van Wetenschappen, Series C 54: 260–271.
• Sanders, R.K. and Smith, D.K. 2005. The endocranium of the theropod dinosaur Ceratosaurus studied with computed tomography. Acta Palaeontologica Polonica 50 (3): 601–616.
• 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.

Update (later the same day)

We’ve added scans of the print-edition coverage that we got in the UK’s national newspapers (and the London-only freebie Metro).  Somehow, seeing it in an actual newspaper still feels more real than the same newspaper’s web-site.  Scan are at the bottom of the paper’s home page.

Sauropods held their necks erect … just like rabbits

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.

The classic reconstruction of Brachiosaurus brancai, from Janensch (1950b: plate VIII. (For some reason, WordPress doesn't allow italics in these captions, hence the roman-font taxonomic names.)

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.

The subhorizontally mounted neck of the Rutland Cetiosaurus skeleton at the Leicester City Museum, in right posterolateral view.

The median part of the subhorizontally mounted neck of the Rutland Cetiosaurus skeleton at the Leicester City Museum, in left lateral view. Mike Taylor for scale.

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.)

Diplodocus carnegii, DinoMorph computer model , showing neutral neck posture, and limits of dorsal and ventral flexibility. From Stevens (2002:fig. 6a). (Note that Stevens's more recent models show a slightly higher neck due to its leaving the torso at a less steep angle.)

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.

A still from Walking With Dinosaurs, episode 2, Time of the Titans, showing Diplodocus in a DinoMorph-compliant posture with a low, horizontal neck. Image copyright the BBC.

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:

Physical DinoMorph model at the AMNH, with horizontal-neck advocate Kent Stevens. Photograph by Rick Edwards, AMNH

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:

Unrestrained awake rabbit, left lateral view, in X-ray, showing vertical neck. From Vidal et al. (1986:fig. 4B)

Amazing.

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):

Taylor et al. (2009: fig. 1), reversed for easy comparison with the previous two images: skull and cervical skeleton of the Cape hare (Lepus capensis) in neutral pose and in maximal extension

(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 selected of life 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:

Diplodocus carnegii head, neck and anterior torso, right lateral view, articulated in habitual posture as hypothesised by Taylor et al. (2009). Skull and vertebrae from Hatcher (1901).

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!

Diplodocus herd -- mostly with necks in habitual raised posture, with one individual drinking. By Mark Witton.

Stay tuned for more on neck posture …

Update

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.

References

• 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.

Ahead by a tail

You’d think that in 100+ posts we’d be starting to exhaust the territory, but there are vast swaths of sauropod vertebral morphology that we haven’t even touched. Like fused vertebrae. Sauropods fused their vertebrae all the time. Some of those fusions are age-related, many are pathological, and some are…hard to classify.

Exhibit A: fused distal caudals in a specimen of Mamenchisaurus hochuanensis described by Ye et al. (2001). In contrast to the terminal caudals comprising the tail club of Shunosaurus, the centra here are not ballooned out. The one in the middle is clearly waisted, as in “narrower in the middle than at the ends” (not the same clearly wasted as your college roommate). The neural, uh, elements are expanded and fused into something that the authors describe as resembling the comb of a rooster. I can’t improve on that metaphor so I won’t try. Here’s the full weirdness, straight from the authors (p. 39):

The posterior caudals are fused with each other, their centra are not expanded, the neural arch is remarkably expanded and the size of the neural canal  and the height of  the neural spines increased. In lateral view, the posterior caudals are cockscomb-shaped.

That’s all pretty weird. The authors go on to speculate that the expanded neural canal indicates that the tail club fin thingy served as some kind of special sense organ. I don’t think that idea is too bold. I don’t think it’s bold enough.

Hypothesis: Mamenchisaurus had a pseudohead on the end of its tail, with fused verts to form a pseudoskull and a big nerve bundle to give the pseudomouth (probably articulated chevrons) and pseudoeyes (possibly heat-sensitive like rattlesnake pits) some lifelike movements and relay thermal images up to the brain. It probably started out as a predator-confusion thing. The carnosaurs would obviously like to attack the inattentive end of the sauropod but these push-me-pull-yous were on the lookout fore and aft! And if the carnosaurs did attack, there was a 50/50 chance they’d bite off the wrong head. Then the pseudohead, which evolved to simulate attention, got so good at it that it was exapted into an actual lookout post at the individual’s farthest extremity. What an advantage those animals had!

But, alas, the caudal pseudohead turned out to be a serpent in paradise. It started getting ideas. Demanding equal time to “teach the controversy” to the forebrains of juvenile conspecifics. Mamenchisaurus became a house divided. First there were pranks, as the real brain started hearing “voices” in its tail. Then outright arguments as the brain and pseudobrain struggled for control of the animal. Finally the pseudohead took over, started marching the animal around backwards. Poor Mamenchisaurus was tripping over logs, which don’t show up so well on infrared, and slipping on its own feces. Lost in delusions  of grandeur, the pseudohead chomped on ferns for hours, unwilling to admit that it couldn’t swallow and too proud to realize that it was starving the animal to death (certain political and economic parallels suggest themselves here).

We all know what happened: Mamenchisaurus died out, the pathetic victim of a caudal takeover, and was replaced by other sauropods that, if perhaps more conservative, could at least keep their tails in line. And the world passed once again into the metaphorical hands of the heads. But even now, 140 million years later, tails the world over recall their ancient glory and plot revenge–perhaps even the tail you’re sitting on right now. If you are quiet, and cunning, you may hear your tail’s defiant murmur: the south will rise again!

Reference

• Ye, Y., Ouyang, H., and Fu, Q.-M. 2001. New material of Mamenchisaurus hochuanensis from Zigong, Sichuan. Vertebrata PalAsiatica 39(4):266-271.

The sauropods of Star Wars

I’m sure Mike will deride this as sordid linkbait, but what the heck. I’ve been meaning to blog about the sauropods of Star Wars for a while now, and I was finally spurred into action by this comment over at TetZoo.

The first (and best) sauropod of Star Wars will be no surprise to anyone with reasonably sharp eyes and rudimentary knowledge of sauropod osteology: the Krayt dragon skeleton that C-3PO walks past on Tatooine is composed mainly of cast sauropod vertebrae.

You can see that the monster’s cervicals have big cervical rib loops. The deeply bifurcated neural spines mean that they are either from a diplodocid or Camarasaurus. Some of them are also fairly long and low-spined, especially those close to the head, which rules out Camarasaurus. I find the purely fictional skull pretty unconvincing next to the real (cast) sauropod vertebrae.

Moving on down the series, we see that all of the dorsals have high neural spines, some of which are deeply bifurcated, which again is consistent with diplodocids but not with Camarasaurus, whose bifurcated spines are all short (and fairly ugly).  The vertebrae also have broad transverse processes that give them a ‘t’ shape. You can see that whoever laid out the dorsals scrambled their order (perhaps deliberately) so that the deeply cleft vertebra in the middle is bordered ahead and behind by verts with little or no bifurcation of the neural spine. In articulated diplodocids, the neural spine cleft first appears in the anterior cervicals, grows larger and deeper through the rest of the neck, and then disappears around the middle of the dorsal series.

So which diplodocid is it? My vote is Diplodocus, probably a cast of the mounted Carnegie skeleton like the one shown here in London’s Natural History Museum (this particular mount turns up here at SV-POW! quite frequently). The cervical rib loops of the anterior cervicals attach near the bottoms of the centra instead of hanging far below them as in Apatosaurus. Also, you can see below that the cervical ribs loops of the posterior cervicals are narrow, as in Diplodocus, but not Apatosaurus (images of Diplodocus cervicals are from Hatcher’s 1901 monograph).

The final piece of evidence for the Diplodocus ID is a closeup of part of one of the vertebrae. According to Wookieepedia (from which I stole the Ep IV screencap I’ve used throughout this post) Lucas and crew left the prop skeleton out in the desert when they were done shooting back in the 70s, and rediscovered it when they returned to Tunisia to film the Tatooine sequences for Attack of the Clones. I don’t know if the skeleton was scavenged by prop hunters before, during, or after the ATOC filming, but pieces of the skeleton turn up on movie prop sites, including the one shown here:

This is a cervical rib of a sauropod, and it looks to me more like the slender ribs of Diplodocus than the massive ribs of Apatosaurus. I could be wrong about the genus, but if the bones in the movie don’t belong to Diplodocus they have to be Apatosaurus, and the balance of the evidence points to Diplodocus.

Oddly enough, Wikipedia states that, “The artificial skeleton used for the movie was left there after filming and still lies in the Tunisian desert. During filming of Attack of the Clones, the site was visited by the crew and the skeleton was still found there. The skull used resembles that of a Diplodocus, a herbivorous dinosaur related to the Apatosaur” (emphasis added). Good call, Wiki-trolls.

The “Krayt dragon” locality has been visited, and blogged about, by paleontologist and paleo-blogger Michael Ryan.

One more thing: Diplodocus and Apatosaurus both have 25 presacral vertebrae. The photo above is not crisp enough to determine precisely how many vertebrae are in the cervical+dorsal regions, but it’s more than 25. Also, none of the dinky anterior cervicals of Diplodocus are visible. So I think they must have gotten two sets of presacrals (possibly two whole columns) and used only the bigger vertebrae. I wonder what happened to the verts they didn’t use…I’d give a non-essential organ for a cast Diplodocus cervical.

That’s it for this one. There is another sauropod (sort of) in Episode IV (sort of), but I’ll wait a week before I blab about that one. I wonder if anyone will guess what it is in the meantime?

The ghost of Christmas past

But also of Christmas future.

Or, perhaps, the spirit (pneuma) of the season.

Merry Christmas to all! We’ll see you back here in 2009.

Cheers,

The SV-POW!sketeers

Airheads

A 3D reconstruction of the paranasal sinuses in a human (from Koppe et al. 1999). You also have paratympanic sinuses that pneumatize the mastoid process of the temporal bone (feel for an inferiorly-directed, thumb-size protuberance right behind each ear).

An x-ray of a pig skull, from here. Can you see the outline of the brain-shaped endocranial cavity?

How about in this x-ray of a rhino skull? Image courtesy of Kent Sanders.

A sectioned cow skull. The bottom half of the endocranial cavity is exposed in the horizontal cut. The vertical cut shows the tiers of sinuses that make up most of the volume of the skull. I think that the middle tier (the large, butterfly-shaped space) is the front part of the endocranial cavity and housed the most rostral bits of the brain; note that it is completely surrounded by sinuses.

Part of a bighorn sheep skull. The pneumatic horncores of bighorns are a useful antidote to the idea that pneumatic bones must be weak.

A cross-section of an elephant skull, courtesy of Project Gutenberg. The cavity at the back marked ‘b’ is the endocranial cavity that holds the brain. The big tube running through the middle is the nasal airway. Everything else is pneumatic. Note that the brain is entirely surrounded by sinuses.

A blown skull of a proboscidean from the bone cellar at the Humbolt Museum. I snapped this on the last day in collections,  on a mad scramble to get whatever non-sauropod pics (gasp!) I might want later. The bumps to the upper right are the occipital condyles; the skull is in left lateral view facing down and to the left.

Paratympanic sinuses (green) surrounding the brain (blue) of an alligator, from David Dufeau’s homepage. Go there for a lot more mind-blowing images of sinuses. The snout of this gator is filled with paranasal sinuses, they’re just not shaded in here.

Sectioned skull of a rhinoceros hornbill, which is pretty much completely filled with paranasal and paratympanic sinuses. Even the lower jaw is pneumatized.

Okay, so now you know that mammals, crocs, and birds are all air-heads. What does any of this have to do with sauropods? Well…

• Archosaurs and mammals evolved cranial pneumaticity independently. Does that mean that cranial pneumaticity is easy to evolve (since it evolved more than once) or hard to evolve (since it only evolved twice)? This is relevant to the question of how many times postcranial pneumaticity evolved.
• Archosaurs evolved cranial pneumaticity before they evolved postcranial pneumaticity. Does that mean that postcranial pneumaticity is the application of a pre-existing developmental program (bone pneumatization) to a new anatomical region (the postcranial skeleton)? Or did the developmental control of pneumatization have to evolve de novo in the postcranium?
• The development of cranial pneumatization in mammals and postcranial pneumatization in birds seems to  follow similar rules. Does that mean that we can apply lessons learned from, say, the development of human sinuses to understand the development of sauropod vertebrae?
• Sauropods and big-headed mammals like elephants have this in common: at the front end they’ve got a big chunk of pneumatic bone. In sauropods, it’s the neck; in elephants, it’s the head. In both cases the big pneumatic organ makes up close to a tenth of the animal’s volume. I don’t know what else to make of that, but maybe you can get mileage out of it at a cocktail party.

I posted these because I was inspired by Darren’s post on dome-headed elephants, because they’re cool, to maybe demystify sauropod pneumaticity a little, or perhaps to re-mystify skeletal pneumatization in general. You have a pneumatic cavity between your brain and your monitor right now. How much time have you spent thinking about that (when you didn’ t have a sinus headache)?

Next time: more Berlin goodness.

UPDATE: By utter coincidence, Ohio University put out a news story about Larry Witmer’s work on sinuses yesterday. Hat tips to Yasmani Ceballos Izquierdo, who posted the link on the DML, and to Mike for sending it on to me. As long as you’re going over there, remember that Larry is one of the Good Guys and puts his papers up for public consumption; the new dino sinus paper is here. It’s great, but it makes the pictures I used here look pretty pathetic. Go have fun!