I floated this idea on Fist Full of Podcasts, and Andrew Stuck gave it a shout-out in the comments, so I’m promoting it to a post.

The idea, briefly, is that sauropods grew fast and had enormous energy demands and even though horsetails and pine needles are surprisingly nutritious (Hummel et al. 2008), they probably suck to eat all the time. Extant herbivores are notoriously carnivorous when no-one is looking, and it’s silly to assume that extinct ones were any different. It seems likely that a big, hungry sauropod, gifted by natural selection with more selfish opportunism than compassion, would probably have viewed a turtle as a quick shot of protein and calcium, and a welcome hors d’oeuvre before stripping yet another conifer or tree fern. Furthermore, said sauropod would have been well-equipped to render the unfortunate chelonian into bite-size chunks, as shown above. The first time might even have been accidental. (Yeah, sure, Shunosaurus, I believe you. [rolls eyes])

Given that sauropods and turtles coexisted over most of the globe for most of the Mesozoic, I’ll bet this happened all the time. I don’t know how to falsify that,* but how could it not have? You’d have to assume that sauropods didn’t run into turtles, or that their mercy outweighed their curiosity and hunger. That’s even more bonkers than turtle nachos.** As Sherlock Holmes almost said, “When you have eliminated the impossible, whatever remains – no matter how stupid/awesome – was probably done by sauropods.”

* “Oh, you found a boatload of turtle shell pieces at your fossil site? How tantalizingly unprecedented – please tell me more!” said no-one ever. Seriously, everyone who works on stuff younger than the Early Jurassic seems to bitch about all of the turtle frags they find, whether they’re looking for Apatosaurus or Australopithecus.

** Not to be all navel-gazey, but that is conservatively the greatest sentence I have ever written.

In conclusion, sauropods stomped on turtles and ate them, because duh. Fight me.

Further Reading

For more sauropods stomping, see:

And for sauropods not eating, but gettin’ et:

Reference

Hummel, J., Gee, C. T., Südekum, K. H., Sander, P. M., Nogge, G., & Clauss, M. (2008). In vitro digestibility of fern and gymnosperm foliage: implications for sauropod feeding ecology and diet selection. Proceedings of the Royal Society of London B: Biological Sciences, 275(1638), 1015-1021.

 

 

Trying two new things this morning: grilling a turkey, and live-blogging on SV-POW!

I like to grill. Steak, chicken, kebabs, yams, pineapple, bananas–as long as it’s an edible solid, I’m up for it. But I’ve never grilled a turkey before. Neighbor, colleague, fellow paleontologist and grillmeister Brian Kraatz sent me his recipe, which is also posted on Facebook for the edification of the masses. See Brian’s excellent writeup for the whole process, I’m just going to hit the photogenic parts here. Oh, and usually I tweak any photos I post within an inch of their lives, but I don’t have time for that this morning, so you’re getting as close to a live, unedited feed as I can manage. Stay tuned for updates.

Enough of that. Let’s rock!

The process starts  more than a day in advance, with the brine. Salt water, fruit, onions, garlic, spices, and some apple juice.

The turkey needs to be entirely immersed in the brine for at least 24 hours. Doing this in a solid container would require an extra big container and too much  liquid to cover the bird. I follow Brian’s method of brining in a triple-layer of trash bags. You can see a turkey roaster peeking out underneath the trash bags. Helps with the carrying.

Put the turkey in the trash bags first, then pour in the brine. Unless you like huge messes.

The genius of the trash bag method on display. You can squeeze out all the air so that the volume of the bag is equal to just the turkey and the brine.

Into the fridge for a day.

First thing this morning: out come the giblets, and save the goodies from the brine. We’ll get back to the neck later.

The bird awaits.

Crucial step: putting in a drip pan. Keeps the coals off to the side for indirect heat, and catches the grease so you don’t burn down the neighborhood.

Putting in the herb butter. I used three short sticks of butter mixed with sage, lemon pepper, and Mrs. Dash. Working the skin away from the meat and then filling the space with butter was extremely nasty. This must be what diverticula feel like.

A chimney is helpful to get the coals going.

To eat is human; to grill is divine.

Smoke bombs: mesquite chips soaked in water, wrapped up in balls of tinfoil, with holes poked on top to let the smoke out.

Fruit and spices into the body cavity.

At this point, I was fairly certain that today would be the greatest day of my life. The turkey is centered over the drip pan, stuffed with goodness, subcutaneously loaded with herb butter, draped with bacon. You can see one of the smoke bombs sitting right on top of the coals.

Know what you’re getting into. This 15 lb bird just barely cleared the lid of my grill.

A little over an hour in. I installed foil heat shields to keep the wings and thighs from cooking too fast. It’s all about the indirect heat. Some of the bacon comes off now, as a mid-morning treat.

Okay, the bird is about halfway done, and I have to whip up some sustainer coals and another batch of smoke bombs. Further updates as and when. Happy Thanksgiving!

UPDATE

I was hoping to get some more pictures posted before we ate, but you know how it is in the kitchen on Thanksgiving Day (or, if you’re not an American, maybe you don’t know, so I’ll tell you: dogs and cats living together, we’re talking total chaos).

The turkey just before I pulled it off the grill. The heat shields turned out to be clutch, I would have completely destroyed the limbs without them. That’s going to be SOP from now on.

Ah yes, the bird, she turned out even more succulent than I hadda expected. Check out the pink shade of the meat just below the skin. I recognize that, from good barbeque, but I’ve never produced it before.

That’s it for the cooking part of today’s program. As for the ultimate fate of the bird…we ate a stupifying amount of it. I sent even more home with our guests. And the other half–yes, half–of this thunder beast is sitting in the fridge. Hello-o leftovers!

And hello-o science!

I was going to post some more pictures of the neck, but I didn’t get around to eating it, so…another time, perhaps. In lieu, here’s Mike’s turkey vertebra in left lateral view (see the original in all its supersized glory here). Note the pneumatic foramen in the lateral wall of the centrum, just behind the cervical rib loop. This is actually kind of a lucky catch; a lot of times with chickens and turkeys, the pneumatic foramina are so far up in the cervical rib loop that they can’t be seen in lateral view.

It used to freak me out a little bit that birds often don’t have their pneumatic foramina in the middle of the lateral wall of the centrum, like sauropods. But a possible explanation occurred to me just this morning as I was planning this post. I think that birds have their pneumatic foramina right where you’d expect them, based on sauropods. I’ll explain why.

The first part of the explanation is that instead of wearing their pneumatic cavities on the outside, like this Giraffatitan cervical, bird vertebrae tend to be inflated from within, with just a few tiny foramina outside. The second part is that birds have HUGE cervical rib loops compared to sauropods. If the sauropod vert shown above had its rib on, the resulting loop would be fairly dainty, the osteological equivalent of a bracelet. The cervical rib loops of birds are more like tubes, they’re so antero-posteriorly elongated.

So take the brachiosaur cervical shown above and shrink all of the external pneumatic spaces by several inches. The cavities on the arch and spine would close up entirely, and the complex of fossae and foramina on the lateral side of the centrum would be reduced to a small hole right behind the cervical rib. Then stretch out the cervical rib loop in the fore-aft direction and voila, you’d have something like a turkey cervical, with a little tiny pneumatic foramen tucked up inside the cervical rib loop.

This doesn’t explain why bird verts are inflated from within instead of being eroded from without, or why sauropods had such dinky cervical rib loops (mechanical what, now?), or why pneumatic diverticula tend to make the biggest holes in the front half of the centrum, adjacent to the cervical ribs. I just think that maybe bird and sauropod pneumaticity are not as different as they  appear at first glance. Your thoughts are welcome.

This is corn on the cob:

Corn on the cob, in cross section, stolen from http://www.istockphoto.com/file_thumbview_approve/214165/2/istockphoto_214165-co rn-cob-cross-section.jpg

Corn on the cob, in cross section. Stolen from http://www.istockphoto.com/file_thumbview_approve/214165/2/istockphoto_214165-co rn-cob-cross-section.jpg

This is a shish kebab:

Most tetrapods are like shish kebabs: a whole lot of meat stuck on a proportionally tiny skeleton.  If you don’t believe me, you can look at the human and cow neck torso cross-sections in Matt’s last post, or check out this ostrich-neck cross-section from his 2003 Paleobiology paper:

Ostrich neck in cross section, CT scan.  From Wedel (2003a: fig. 2)

Ostrich neck in cross section, CT scan. From Wedel (2003a: fig. 2)

Remember that this is a freakin’ ostrich — of all extant animals, one of the ones with a most extreme long, skinny neck.  And yet, if sauropods were muscled like ostriches, then their necks would have looked like this in cross section:

Putative shish kebab-style sauropod neck in cross section.  Ostrich soft-tissue from Wedel (2003a: fig. 2), Diplodocus vertebra cross-section from Paul (1997: fig. 4) scaled to match size of ostrich vertebra

Putative shish kebab-style sauropod neck in cross section. Ostrich soft-tissue from Wedel (2003a: fig. 2), Diplodocus vertebra cross-section from Paul (1997: fig. 4) scaled to match size of ostrich vertebra

And soft-tissue reconstructions would have to look like this:

Diplodocus with its neck as fat as an ostrich's.  Modified from Paul (1998: fig. 1F)

Diplodocus with its neck as fat as an ostrich's. Modified from Paul (1998: fig. 1F)

Which, happily, no-one is suggesting.  Instead, published reconstructions of sauropod neck soft-tissue are startlingly emaciated.  As exhibit A, I call this pair of Greg Paul cross-sections:

Diplodocus and Brachiosaurus neck cross-sections, showing very light musculature.  From Paul (1997: fig. 4)

Diplodocus and Brachiosaurus neck cross-sections, showing very light musculature. From Paul (1997: fig. 4)

(Yes, the Diplodocus on the left is the one I used in the photoshopped ostrich cross-section above.  It’s instructive to compare Paul’s original with the What If It Was Like A Big Ostrich version.)

Paul’s reconstructions seem to be widely considered too lightly muscled.  But even the very careful and rigorous more recent reconstructions of Daniela Schwarz and her colleague show a neck much, much thinner than that of the ostrich:

Diplodocus neck cross-sections.  From Schwarz et al. (2007: fig. 7a)

Diplodocus neck cross-sections. From Schwarz et al. (2007: fig. 7a)

Although Schwarz has put a lot more soft tissue onto the neck vertebrae than Paul did, it is still a tiny proportion of what we see in extant animals — even the ostrich, remember, which has a super-thin neck compared with pretty much anything else alive today.  If sauropod necks were muscled as heavily as those of, say, cows, then the soft tissue would pretty much reach down to the ground.  But they weren’t: they were more like corn on the cob, with a broad core of skeleton and relatively little in the way of delicious edibles festooned about it.

So why is this?  Why does everyone agree that sauropod necks were much less heavily muscled than those of any extant animal?

It’s a simple matter of scaling.  A really big ostrich might have a neck 1 m long.  (Actually, ostriches don’t get that big, but let’s pretend they do because it makes the maths easier).  If the x meter-long neck of a sauropod was just a scaled-up ostrich neck, then it would be x times longer, x times taller and x times wider, for a total of x^3 times as voluminous and therefore x^3 times as heavy.  But the cross-sectional area of the tension members that support it is only x times taller and x times wider, for a total of x^2 times the strength.  In total, then, the neck’s mass/strength is x^3/x^2 = x times as great as in the ostrich.  (The sauropod neck’s mass also acts further out from the fulcrum by an additional factor of x, but that is cancelled by the fact that the tension in the neck also acts x times higher above the fulcrum.)

It seems intuitively obvious (which is is code for “I have no way to prove”) that you can’t reasonably expect the neck muscles of a giant ostrich to work ten times as hard as they do in their lesser cousins, which is what you’d need to do for the 10 m neck of, say, Sauroposeidon.  So simple isometric scaling won’t get the job done, and you need to restructure the neck.

But how?  Surely just reducing all the muscle around the vertebrae can’t help?  No indeed — but that is not really what sauropods were doing.  If you look at the typical sauropod-neck life restoration, you’ll see that the proportional thickness of the neck is actually not too dissimilar to that of an ostrich — rather thicker, in fact.  If you scaled an ostrich neck up to sauropod size and compared it with a real sauropod neck, you would find not that the soft tissue was too fat, but that the vertebrae were too thin.

And so we come to it at last: rather than thinking of sauropods as having reduced the amount of soft-tissue hanging on the cervical vertebrae, we do better to think of them as having kept a roughly similar soft-tissue profile to that of an an ostrich, but enlarging the vertebrae within the soft-tissue envelope.  Of course if you just blindly made the vertebrae taller and wider, they would become heavier in proportion, which would defeat the whole purpose of the exercise — but as everyone who reads this blog surely knows by now, sauropod cervicals were extensively lightened by pneumaticity.  By bringing air into the center of the neck, they were effectively able to displace bone, muscle and ligament away from the centre, so that they acted with greater mechanical advantage: higher epaxial tension members, lower hypaxial compression members, and more laterally positioned paraxials.

It’s a rather brilliant system — using the same volume of bone to achieve greater strength by displacing it outwards and filling the center with air (and, in doing so, also displacing soft tissue outwards).  And it will be hauntingly familiar to anyone who loves birds, because it is of course exactly what birds (and pterosaurus) have done in their long bones: the hollow humeri of flying vertebrates famously allow them to attain greater strength — specifically, resistance to bending — for the same volume and mass of bone.  It’s a neat trick when done with long bones, but it takes a truly awesome taxon to do it with the neck.

So maybe sauropods were not corn on the cob after all.  Maybe they were Hostess Twinkies.

Hostess Twinkie.  Not truly pneumatic, as the internal cavity is filled with adipose tissue rather than air, but do you have any idea how difficult it is to find good images of hollow junk food?

Hostess Twinkie. Not truly pneumatic, as the internal cavity is filled with adipose tissue rather than air, but do you have any idea how difficult it is to find good images of hollow junk food? Stolen from http://dixiedining.files.wordpress.com/2008/07/twinkie_070918_ms1.jpg

And now for something completely different

Now that I’ve finished my Ph.D at the University of Portsmouth, what am I going to do with the rest of my scientific life?  I’ve always said that I have no intention of going into palaeo full time: my knowledge is far too narrow for that, so that even if paid jobs were not in insanely short supply, I wouldn’t stand much chance of getting one.  And in any case, I’d hate to get into the all-too-common situation of being up against a friend for a position we both wanted. Throw in the fact that I really enjoy my computer-programming day-job and it seems pretty clear that what I need is an unpaid affiliation that lets me get on with lovely research.

Well: I am absolutely delighted to announce that, as of last month, I am an Honorary Research Associate in the Department of Earth Sciences at UCL.  It’s not just that UCL is such a well-respected institution — see that Wikipedia article for some details — more importantly, it’s where Paul Upchurch hangs out, as Senior Lecturer in Palaeobiology.  Sauropod fans will be familiar with Paul’s characteristically detailed and careful work, from his pioneering work on sauropod phylogeny (Upchurch 1995, 1998), through his and John Martin’s indispensible Cetiosaurus makeovers (Upchurch and Martin 2002, 2003) to the state-of-the art review that he lead-authored for Dinosauria II (Upchurch et al. 2004) and the Tokyo Apatosaurus monograph (Upchurch et al. 2005).  What many of you won’t know is what an excellent collaborator he is — quick, conscientious, insightful and diplomatic.  We’ve already collaborated on a few short papers (Upchurch et al. 2009 and a couple of Phylocode companion-volume chapters that are in press), and I hope there will be more in the future.

References

Taco

This is a taco.

Corndog

This is a corn dog.

Vertebra outlined in green. Click for unmarked original.

Vertebra outlined in green. Click for unmarked original.

Here’s a cross-section of a human. In the terms of fast food, people are corndogs. Most of us even have an outer ring of yellow adipose ‘breading’.

Vertebra oulined in red. Click for unmarked original.

Vertebra oulined in red. Click for unmarked original.

Here’s a cross-section of a cow. In an example of function following form, cows are, and often become, corndogs.

Note that in both the human and the cow the spaces between the neural spine and transverse processes are completely filled with back muscles, which in fact bulge out beyond the tips of the neural spine, as we also saw here. This despite the common paleoart convention of presenting dinosaurs as thin layers of skin conforming perfectly to the underlying skeleton. Just Say No to shrink-wrapped sauropods!

Diplodocus torso xs

Here is Figure 17 from Holland (1910), one of the most badass scientific smackdowns ever published, in which Holland wiped the floor with Hay, Tornier, and the idea of sprawling sauropods. On the left are torso skeletons of three lizards and a croc; on the right is an anterior dorsal with articulated ribs from Diplodocus. As you can see, it’s a taco, and its taconic form would be perfected if it could roll supine.

The point of the post is not that sauropods had deep, slab-sided bodies. We’ve covered that before. The point is that sauropod torsos are seriously weird. In mammals, the dorsal ribs arch up and out, away from the vertebra, before sweeping around to define the anterior body wall.  In lizards, the proximal part of each rib sticks out sideways. In sauropods, the ribs point down. This is mainly because the vertebrae are FREAKIN’ HUGE compared to the size of the body. Whereas in the mammals and lizards the dorsal vertebrae are titchy little things that span a small fraction of the width of the torso, in Diplodocus and other sauropods the dorsal vertebrae account for about half. (The cow cross-section missed the transverse processes, so that vert looks narrower than it actually is.)

This is relevant when we think about the function of pneumaticity. When I write that pneumaticity lightened vertebrae, I usually mean relative to that same vertebra if it wasn’t pneumatized. But we could also ask if the pneumatic vertebra is lighter than a vertebra from a similar-sized animal that lacks pneumaticity–except that, for big sauropods, there are no similar-sized terrestrial animals without pneumaticity to compare.

Imagine that in a big sauropod the dorsal vertebrae are three times as wide and three times as tall as they would be in a similar-sized mammal. They should weigh nine times more. But let’s also assume that the vertebrae of the sauropod are 85% air by volume, which is in fact pretty typical for Early Cretaceous brachiosaurids. The mass of the dorsal column relative to that of the mammal is then 9 x 0.15 = 1.35, a little heavier, but not much (I’m assuming the length of the torso is the same in the two animals). Bigger bones mean better lever arms for the muscles and lower bending stresses on the ribs, which can function more like curtains and less like cantilevered beams.

I can’t think of much published discussion of this stuff as it relates to sauropods, but it seems like it might be important.

Reference

Holland, W.J. 1910. A review of some recent criticisms of the restorations of sauropod dinosaurs existing in the museums of the United States, with special reference to that of Diplodocus carnegiei [sic] in the Carnegie Museum. American Naturalist 44:259-283.