Sauropod gauges

Those familiar with sauropod trackways (and who of us isn’t?) will know that these are often described as ‘wide gauge’ or ‘narrow gauge’ depending on the separation between the left and right sets of prints of a given animal. Obviously sauropods would have had trouble swinging their legs under the midline of the body when walking so they leave two parallel sets of tracks, though the gap between these can be low or high.

This is something I’ve read many times and certainly have no truck with the idea. But it’s hard to *see* such a possible difference on a single sauropod specimen when you have nothing else to compare it to. Thus once more we turn to the Carnegie and their pair of giants. Conveniently, these animals are of pretty similar gross dimensions so the comparison is easier to make and look at the difference and, wow. You can probably walk though the legs of Apatosaurus (upper) quite easily, but you’d have to turn sideways or squeeze a little to get though those of Diplodocus. It’s quite a difference for two animals that are fairly close relatives and of such similar size.

13 Responses to “Sauropod gauges”

  1. 1 Heinrich Mallison 06/02/2012 at 1:42 pm

    >>Obviously sauropods would have had trouble swinging their legs under the midline of the body when walking
    then why is it that many tracks show the feet touching or even overlapping the midline?

    All museum mounts are in standing posture: legs straight down. During walking, the limbs were adducted – just not as far in wide-gauge sauropods (where some space remains between the footprints) as in narrow-gauge ones (where we see overlap of the midline).

    • 2 David Hone 06/02/2012 at 2:22 pm

      “>>Obviously sauropods would have had trouble swinging their legs under the midline of the body when walking
      then why is it that many tracks show the feet touching or even overlapping the midline?”

      I’ve never seen any that do overlap more than a little. Though I should really have clarified that in comparison to tracks from small mammals or bipeds where they can be really in line.

      • 3 Heinrich Mallison 06/02/2012 at 2:24 pm

        Oh, OK, I see what you mean!
        The “best” I have seen is the heels (i.e., posteriormost 20% of the pes) fully on the midline.

      • 4 David Hone 06/02/2012 at 2:27 pm

        Wow, I really didn’t know any of them could even do that much. Cool. Don’t suppose you have a reference or pic do you?

      • 5 Heinrich Mallison 06/02/2012 at 2:33 pm

        I don’t remember where that was, may have been a slide in a talk last year or so. Swiss trackway, maybe? I remember that someone pointed out that the overlap was so strong, and that I thought of all the trouble I had getting my models not to sway too much.

  2. 6 Henrique Niza 06/02/2012 at 2:40 pm

    Extant large, terrestrial mammals like elephants and rhinos have their legs placed under the mid-line of the body when walking and that is probably most likely true to sauropods, except maybe titanosaurs since they have a much wider pelvis than other sauropods.

    • 7 David Hone 06/02/2012 at 2:57 pm

      It depends what you mean by ‘in the midline’. As in the exchange with Heinrich above, there’s a huge difference between ‘the feet get close to the midline’ and ‘every foot falls right on the midline with half the pes either side of it’. I really don’t think rhinos, elephants or giraffes (and as noted above, certainly not sauropods) get anywhere near that second condition, and certainly not like you can see in small mammals or theropods for example.

  3. 8 Mike Taylor 06/02/2012 at 3:44 pm

    I think the usual working definition of “narrow” and “wide-gauge” trackways is that you can draw a straight line down the middle of the latter without touching the any of the individual prints, but you can’t with the latter. General wisdom is that Apatosaurus, like diplodocids in general, would have been narrow-gauge. Pretty impressive given your photo! (Mind you it look like the coracoids have been wrapped around the from rather less than in the Diplodocus mount, resulting in the shoulder glenoids being rather more laterally located.)

    • 9 David Hone 06/02/2012 at 3:49 pm

      Yeah, I did wonder if the mount positions might affect this a bit, but the general point of the discrepency was big enough to illustrate the point.

  4. 10 Jaime A. Headden 06/02/2012 at 3:47 pm

    Seems that Scott Hartman was talking about this a while back, going so far as to suggest that the breadth of the gauge in some models may be somewhat inaccurate because the “broad-gauge” tracks are not really that wide to begin with.

  5. 11 Robert A. Sloan 06/02/2012 at 5:23 pm

    Definitely a great article thoroughly enriched by a long comments tail. Thank you, Dave – and thank you to all the other commenters!

    I’m the dummy again – always paid too much attention to theropods, didn’t realize there were two distinct groups among sauropods. Coolness!

    I’ll bet my beloved theropods did pay attention though and adapt their tactics depending on which type of sauropod they hunted.

  6. 12 Matt 07/02/2012 at 12:14 am

    Am I the only person who thinks they look like ‘before’ and ‘after’ weight loss photos.

  1. 1 drip | david’s really interesting pages… Trackback on 14/02/2012 at 11:30 am
Comments are currently closed.

@Dave_Hone on Twitter


Enter your email address to follow this blog and receive notifications of new posts by email.

Join 576 other subscribers

%d bloggers like this: