Tutorial 6: Air-space proportion in pneumatic sushi

August 12, 2008

Matt is staying here at Taylor Towers for a couple of weeks while his wife spends some quality time with some leprous human remains in Bradford (yes, really). Since both Matt and I are big fans of sushi, I took a stab at making some at home on Sunday night:

Fig. 1. Sushi plate, poorly preserved due to predation

Fig. 1. Sushi plate, poorly preserved due to predation

We noticed that the spring onion in one of the rolls had held its shape sufficiently well to preserve an air-space running along the length of the roll:

av, avocado; cs, crab-stick; pf, pneumatic foramen; pr, prawn.

Fig. 2. Spring-onion california roll, cross-section in anterior view. A, photograph; B, interpretive drawing. Anatomical abbreviations: av, avocado; cs, crab-stick; pf, pneumatic foramen; pr, prawn.

Using the technique of Wedel (2005:212-213), we can calculate the air-space proportion of this roll (ASP) by dividing the area of the enclosed pneumatic space by total cross-section.

fig. 7.5)

The simplest way to do this is to reduce the image to simple black-and-white with a grey background and count the pixels:

Fig. 4. Spring-onion California roll depicted in figure 2, with solid material drawn in black and pneumatic space in white.

Fig. 4. Sushi roll depicted in figure 2, with solid material drawn in black and pneumatic space in white.

According to image-processing program, the full-sized version of this images has 21961 white pixels and 302993 black pixels, yielding an ASP of W/(W+B) = 21961/(21961+302993) = 0.067, or 6.7%. This is a very low value compared to most sauropod vertebrae: according to Wedel (2005:table 7.2), values are mostly in the range 50-70% — nearly ten times as pneumatic as this sushi roll — with Sauroposeidon reaching 89% in a cervical prezygapophyseal ramus.


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23 Responses to “Tutorial 6: Air-space proportion in pneumatic sushi”

  1. Darren Naish Says:

    I am speechless.

  2. Mike from Ottawa Says:

    while his wife spends some quality time with some leprous human remains in Bradford

    Bradford, eh. At least the leprous human remains mean the trip’s not all bad.

  3. Mike from Ottawa Says:

    Being more serious, I think you may be comparing apples to oranges. That roll looks to my, albeit amateur, eyes like a posterior caudal, so comparison with dorsals and cervicals of others such as Sauroposeidon may be misleading as to the general state of pneumatization in Sushisaurus esculentus.

    BTW, I think that is ‘scavenging’, not ‘predation’. More accurate, if less appetizing.

  4. Out of idle curiosity, what software packages were you using for the image analysis?

  5. Mike Taylor Says:

    I am a hardcore Linux hacker (I only work on sauropods in my spare time), so I use the GIMP for nearly all my image-manipulation needs (http://www.gimp.org). People who have used PhotoShop, its moral equivalent, tend to dislike the GIMP, but I think it’s awesome: probably, it’s just that whichever one you learn first will leave the other feeling alien.

    I said _nearly_ all my image manipulation needs. The exception is Inkscape (http://www.inkscape.org/) which is a vector graphics editor analogous to something like Illustrator or Corel Draw. This is pretty good, but doesn’t feel as polished as the GIMP. It has one wonderful feature, though, which is the ability to read and write SVG, an open XML format for representing diagrams. This is great for me, because as a programmer I can and do write code that generates SVG (for example, to illustrate changes in diversity through time), then import the result into Inkscape to pretty it up.

  6. I think this is brilliant! You should submit this for a poster session at SVP. My one concern is that you don’t take into account the inherent difference in the density of rice vs. the density of sauropod bone. I may be wrong about this, but isn’t rice, (even high-quality sushi rice), considerably less dense than bone? Also, there is a lot of pneumaticity in the spaces between the grains of rice, which is not demonstrated in a photo of a complete maki roll. Perhaps, for best results, you should consolidate the maki material and then slice it into wafer thin sections before using your imaging technique. Then you could calculate an average from the resulting data, which may or may not be considerably different from the results obtained by photographing a single section. Also, have you taken into account how your data might change if the sushi was served on the naked body of a high-priced geisha? For the sake of a robust sample, I think you should try naked geisha technique and see what happens. Please let me know when you plan to do this, because I’d like to come over and observe the process.

  7. Mike Taylor Says:


    Unfortunately, our funding does not cover the process you suggest. (In fact, it doesn’t cover anything at all — least of all the actual sushi.)

  8. Nathan Myers Says:

    John: I think you would need to freeze the sushi, first, in liquid nitrogen, which would be uncomfortable for the assistant.

    I do wonder about 2D vs. 3D confoundings, although not for sushi. Does averaging sections account well enough for “the ends”? A 3D MRI scan, followed by reconstruction in a 3D printer, ought to give a more defensible result, and be more fun, too, than GIMPing. Re-coding to represent a “level” in a modern video game, you could explore the interior, color-coding the walls with spray paint as you go. A museum constructed according to a 3D scan of a single vertebra would be a wonder of the world, although visitors might bump their heads more than they’d like. (Issue miners’ helmets, with lights.)

  9. I’m curious about the Fig. 2 information; after sectioning how do you distinguish anterior from posterior along the long axis?

    Also (and to confess my ignorance) has there been a good assesment of ant-post intravertebral variation in pneumaticity? My coauthor did serial section of one of the supersaur ribs to that effect, but I imagine most curatorial types are less enthusiastic about serial sectioning of vertebrae.

  10. Mike Taylor Says:


    If it comes to that, how do you distinguish anterior/posterior from dorsal/ventral or left/right?

    And, no, there has so far been NO anywhere-near rigorous assessment of intravertebral variation in ASP along the axis — Matt’s 2005 paper is still the state of the published art on this, and as he says in that paper (p. 213), “this research is in progress and I will present more complete results elsewhere. The results should be approached with caution: I have only analyzed a few vertebra from a handful of taxa, and only one of a few cross-sections for each bone, so the results may not be representative of either the vertebrae, the regions of the vertebral column, or the taxa to which they belong.” As it happens, I was saying to Matt just last night that the absurdly high figure of 0.89 for Sauroposeidon is probably anomalous because it’s the only measurement so far taken of a prezygapophyseal ramus. Maybe all sauropods have prezyg rami that are more penumatic than their centrum bodies?

  11. If we are talking about bone density, shouldn’t we use the most direct method of assessing density? Wouldn’t displacement of vertebrae in liquid give us more useful data? I realize that this method is just as problematic as any others, but it seems like it keeps one step closer to the raw data, i.e. the fossil, than a photograph or a graphic representation of a fossil.

    Thinking laterally, here’s an interesting paper on estimating the density of seal pups using displacement, which might point out some of the pitfalls of using displacement:

  12. Sorry, I didn’t realize that leaving links in comments is not allowed. For anybody who is interested, the paper is:
    “Estimation of body volume and density in California sea lion pups,” S. Luque and D. Aurioles-Gamboa, Journal of the Marine Biological Association of the UK (2002), 82: 1019-1022 Cambridge University Press.

  13. Mike Taylor Says:


    Estimating the density of a bone by immersion in liquid is just fine if the parts that were air in life are still air now (and also if the curators are happy for you to dunk their precious bones in water!) But for sauropod pneumaticity, it ain’t so: the holes are invariably filled with matrix, and even the most careful preparation can’t begin to get all the crud out of the camellae of a camellate or somphospondylous vertebra.

  14. DDeden Says:

    Fine work gents, astounded at the dedication (counting all those pixels). Seeing the word ‘antpost’ (now understood to mean anterior-posterior) inspired this awesome yet useless question:

    Which is more pneumatic, a termite mound or a sauroposeidon cervical vertebrae?

  15. Tom Luczycki Says:

    Compelling. I am curious if you may have provided influence for maria Brumm’s “The Igneous Petrology of Ice Cream”


  16. [...] 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 [...]

  17. Graham King Says:

    I love it. and who needs a reason why?


    Ok here’s a reason. Occasional pictures of food remind me that the purpose of saliva is to aid eating, and so, prompt me to eat occasionally; not to spend all day drooling over pictures of dinosaurs and suchlike forgetting to eat.

    I think that is a real kindness. Thanks guys, you saved me from starving!

    [PS actually I am guessing saliva is multipurpose even more than we have discovered/realized yet.]

  18. [...] 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 [...]

  19. [...] post he showed photographs of both this chunk and its other half. He also briefly discussed the Air Space Proportion (ASP) of the specimen, and I’ll expand on that [...]

  20. [...] As usual, bone is black, air is white, and everything else is gray. And the ASP is: [...]

  21. [...] complex, and it doesn’t have any obvious juvenile characters other than just being small. The ASP is about as high as it gets in diplodocids. Which, as you may remember, is not nearly as high as it [...]

  22. [...] complex, and it doesn’t have any obvious juvenile characters other than just being small. The ASP is about as high as it gets in diplodocids. Which, as you may remember, is not nearly as high as it [...]

  23. […] by the total–we just use ASP for air-filled bones and MSP for marrow-filled bones. See Tutorial 6 and these posts: one, two, […]

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