Apatosaurusminimus left ischium

July 4, 2012

Here is another illustration that I prepared for the forthcoming “Apatosaurusminimus redescription. Compare this with the sacrum and fused ilia from the previous post.

Left ischium of AMNH 675, “Apatosaurusminimus. Left column: proximal. Middle column, top to bottom: medial (inverted), dorsal, lateral, ventral (all with proximal to left). Right column, distal. Click through for very high resolution (4810 x 5229).

Can you tell what it is yet?

By the way, I’d appreciate some advice on the directional nomenclature here. Since I’ve illustrated the lateral view with the long axis horizontal, I’m referring to the margin that’s closest to the tail as “dorsal” and the margin closest to the ground as “ventral”. But since the ischium is directed more or less posteroventrally, I guess you could equally make a case for designating those two aspects as “posterior” and “anterior” respectively. The third alternative is to embrace the diagonality and call them “posterodorsal” and “anteroventral”. Is one of these schemes conventional?


12 Responses to ““Apatosaurusminimus left ischium”

  1. dinogami Says:

    The last one is the most correct and accurate. Similar problems have plagued coracoid and sternum terminology… :-/

  2. I remember seeing some sort of directional disclaimer in the Majungasaurus scapula and forelimb paper. Perhaps you can do the same, so you can use the directions that work best for you.

  3. Mike Taylor Says:

    Jerry wrote: “The last one is the most correct and accurate.”

    Ah, but Jerry, you’re the one person I can’t trust on anatomical nomenclature! :-)

    Rutger, yes, I have written such directional disclaimers about shoulder-girdle elements. Here is the relevant section from my 2009 Brachiosaurus paper:

    Many different sets of directions have been used to describe sauropod coracoids, with the edge furthest from the scapular articulation having been variously described as median (e.g., Seeley, 1882), inferior (Riggs, 1904), anteromedial (Powell, 1992), distal (Curry Rogers, 2001) and anterior (Upchurch et al., 2004), and the designation of the other directions varying similarly. I follow Upchurch et al. (2004) in describing the coracoid as though the scapulocoracoid were oriented horizontally: the scapular articular surface is designated posterior, so that the glenoid surface of the coracoid is considered to face posteroventrally.

    But I thought there might be a standard for pelvic elements.

  4. Dino Hunter Says:

    Just a technical question….how can you call this an illustration when its a photograph? Aren’t illustrations ‘draw’ with pen/ink or pencil?

  5. Mike Taylor Says:

    Hi, Tracy, I don’t think “illustration” is restricted to drawn and painted representations. The Wikipedia definition is “a rendition (that could be presented as a drawing, painting, photograph or other work of art) that is created to elucidate or dictate sensual information (such as a story, poem or newspaper article)”; and Merriam-Webster gives meaning 2b (the relevant one) as “a picture or diagram that helps make something clear or attractive”, with the example “They selected photographs to use for the illustration of the book.”

  6. Mickey Mortimer Says:

    I think this ischium kills any therizinosaur identification.

  7. Cary Woodruff Says:

    I have to agree with Jerry on posterodorsal and anteroventral.

  8. Mike Taylor Says:

    I was reluctant to use the clumsy terms posterodorsal and anteroventral because I thought they would drag in the equally clumsy companion directions anterodorsal and posteroventral — but of course I am using proximal and distal for those, so the damage isn’t so great. Maybe I’ll do as you suggest, then.

    Matt, any preferences?

  9. Mike, I seem to recall addressing the issue of direction and orientation for measurement and discussion when I discussed Part 1, Part 2 and Part 3 of a mandible. I think the issue of precise orientation toward what you are asking are directly relevant. I also put this little thing together: The ischium, with axes and directions applied.

  10. My personal perspective is to settle for two, or maybe three sets of measurements. This may be a standard for the future, although I notice a reluctance on some to keep the measuring tape going far longer than they should. This is a perfect example of why you need to take a variety of measurements, covered on MY blog at least three times so far.

    Primarily, the orientation of your bone determines what portion is “dorsal,” or so forth, without having to quibble about using three-dimensional addresses in your language (converging on German in degrees of how many words get clumped together) that cause readers to go cross-eyed. You “solve” this by fixing your orientation, for whatever reason (humerus in flexed, or rotated bird-style; ischium in life or in flat position) and then determine the natural directions. Of course, sauropods make manipulation of objects harder, but with 3D rendering this won’t be a problem at all.

    You then take a point on the object and describe what you see or measure from that point along the three axes now established by this object. This way, you can rotate or reverse the bone and still have a manner in which to say “It is THIS long” and “THIS wide,” and the reader knows EXACTLY where you are deriving your measurements.

  11. Mike Taylor Says:

    Thanks, Jaime, that all makes sense to me.

  12. […] from Osborn and Mook’s (1921) gargantuan Camarasaurus monograph, again prepared largely for comparison with “Apatosaurus” minimus. Last time, I showed you one of O&M’s pubis illustrations. Now […]

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