(First of all, for anyone who’s not familiar with the plural of “pubis”, it’s spelled “pubes” but pronounced “pyoo-bees”. Stop sniggering at the back.)

As Matt and I struggle to figure out the partial pubis that is one of the elements of the “Apatosaurus” minimus specimen AMNH 675, one of the most helpful references is Osborn and Mook’s (1921) epic monograph on Camarasaurus. It’s not that 675 particularly resembles Cam — it doesn’t. It’s just that Osborn and Mook is very lavishly illustrated, so that it is (as far as I know) the only published paper in the history of sauropod studies to have shown a sauropod pubis in more than one aspect.

Here is one of the two pubes that they illustrated in the six cardinal aspects:

This shows the left pubis AMNH 5761/Pb.2. Top row: proximal aspect, with anterior to left. Middle row, from left to right: anterior, lateral, posterior, medial. Bottom row: distal, with anterior to left. Heavily modified from Osborn and Mook (1921: fig. 102) — cleaned up, lettering and lines removed, recomposed in a more informative layout, views rescaled to better match each other, and tweaked for colour.

As usual, click through for full resolution (only 1159 x 940 this time).

As you can see, the pubis is a very strangely shaped bone, twisted and with odd rugosities everywhere. If you’re very lucky, we’ll discuss these in more detail later. For now, the take-home message is that sauropod pubes are very weird and confusing, and the simple lateral view that’s typically all you ever see is terribly misleading.

References

• Osborn, Henry Fairfield, and Charles C. Mook. 1921. Camarasaurus, Amphicoelias and other sauropods of Cope. Memoirs of the American Museum of Natural History, n.s. 3:247-387, and plates LX-LXXXV.