Foster and Wedel 2014 fig 3 - dorsals

Fig. 3. MWC 8028, Haplocanthosaurus dorsal vertebrae. A. Lateral view of dorsal centrum with bottom edge of lateral pneumatic fossa preserved. B. Dorsal view of same centrum as in A, showing the median septum between the paired lateral fossae. C. Lateral view of dorsal centrum with smaller segment of the lateral pneumatic fossa margin preserved. D. Dorsal view of same centrum as in C, again showing the median septum and paired lateral fossae. E. Lateral view of dorsal centrum with partial pleurocoel preserved. F. Cross-sectional (posterior) view of same dorsal as in E. G. Dorsal neural spines in lateral (top) and anterior or posterior (center, bottom) views. Scale bars = 10 cm.

Right on the heels of Aquilops last week, my paper with John Foster on the new specimen of Haplocanthosaurus from Snowmass, Colorado, was just published in Volumina Jurassica. I’ll have more to say about it later, but right now I am up against a deadline on a big project and I need to go work on that. I’m only popping up here to note two quick things.

First, if you’re not familiar with Volumina Jurassica – and I wasn’t, before this project – it’s a free-to-access* journal that publishes papers on all aspects of the Jurassic. The current issue is specifically dedicated to the Jurassic formations of the American West. There’s a lot of interesting stuff in there, but of special interest to SV-POW! readers will be the paper by Cary Woodruff and John Foster on the legendary and possibly apocryphal Amphicoelias fragillimus.

* But not truly open access since the journal claims to retain exclusive rights to distribute the papers. That seems like a quaint affectation now that the internet is here, but whatever – at least they let anyone download the PDF for free, which is primarily what I care about.

Foster and Wedel 2014 fig 4 - sacrum

Fig. 4. Sacra of Haplocanthosaurus.  A. MWC 8028, sacrum in right lateral view. B. MWC 8028, close-up of S4 and S5 centra highlighting pneumatic fossae. C. MWC 8028 with divisions between the vertebrae overlaid. D. CM 879, sacrum in right lateral view with divisions between the vertebrae overlaid. E. CM 572 in right lateral view, after Hatcher (1903c: plate 4). B–E are not shown at the same scale, scale bar for A = 20 cm. Note that the neural arches in CM 572 were restored during preparation, and the sacral neural spines as shown here are probably lower than they would have been in life.

Second, the figure resolution in the PDF of the Haplocanthosaurus paper is not stellar, so as is the case with almost all of our papers, the full-color, high-resolution figures are available at the paper’s page on the sidebar.

Gotta run.

For our previous posts on Haplocanthosaurus, go here; for those on Amphicoelias, including Mike’s very popular, “How big was Amphicoelias fragillimus? I mean, really?”, go here.

References

Illustration talk slide 39

Illustration talk slide 40

Illustration talk slide 41

Illustration talk slide 42

Illustration talk slide 43

The Sauroposeidon stuff is cribbed from this post. For the pros and cons of scale bars in figures, see the comment thread after this post. MYDD is, of course, a thing now.

Previous posts in this series.

Reference:

Wedel, M.J., and Taylor, M.P. 2013. Neural spine bifurcation in sauropod dinosaurs of the Morrison Formation: ontogenetic and phylogenetic implications. Palarch’s Journal of Vertebrate Palaeontology 10(1): 1-34. ISSN 1567-2158.

Illustration talk slide 13

Illustration talk slide 14

Illustration talk slide 15

Somewhat lamely, this is the only slide I had in about lighting. I left it up while I talked about the most important points, which are:

  • Don’t use a flash unless you absolutely have to.
  • If you can swing it, the common convention is to have specimens illuminated from the upper left.*
  • If you have the time, it’s not a bad idea to bracket your Goldilocks shot with brighter and darker photos, by fiddling with your camera settings.

* I happily violate this convetion if illumination from another angle shows the specimen to better advantage–and if I have any control over illumination. Working with big bones in some collections, you basically have overhead florescent lights and that’s it. The NHM shot above may look not-so-hot, but there we at least had a desk lamp we could move around. In a lot of places I’ve worked, I didn’t have even that.

The other posts in this series are here.

No time for anything new, so here’s a post built from parts of other, older posts.

The fourth sacral centrum of Haplocanthosaurus CM 879, in left and right lateral view. This is part of the original color version of Wedel (2009: figure 8), from this page. (Yes, I know I need to get around to posting the full-color versions of those figures. It’s on my To Do list.)

Note the big invasive fossa on the right side of the centrum. The left side is waisted (narrower at the middle than the ends) like most vertebrae of most animals, but has no distinct fossa on lateral face of the centrum. What’s up with that? Here’s an explanation from an old post (about another sauropod) that still fits:

Now, this asymmetry is also weird, but it’s expected weirdness. Pneumaticity seems to just be inherently variable, whether we’re talking about human sinuses or the facial air sacs of whales or the vertebrae of chickens. It appears that the form of pneumatic features is entirely determined by local tissue interactions, with little or no genetic control of the specific form. Think of it this way: genes prescribe certain developmental events, and those events bring tissues into contact–such as pneumatic epithelium and bone. The morphology of the bone arises out of that interaction, and each interaction of bone and pneumatic epithelium has the potential to produce something new. In this case, the diverticula on the left side of the vertebral column come from the lungs or air sacs on the left, and those on the right side come from the lungs or airs sacs on the right, so it’s really two sets of diverticula contacting the bone independently. The wonder, then, is not that pneumatic bones are so variable, but that we see any regularities at all.

Plateosaurus trossingensis AMNH 6810 sacrum and pelvis in left dorsolateral view

We’ve shown a lot of sauropod sacra around here lately (for example here, here, and here), so here’s a little look back down the tree.

You haven’t heard from me much lately because I’ve been busy teaching anatomy. Still, I get to help people dissect for a living, so I can’t complain.

Further bulletins as events warrant.

In a comment on the previous post, Steve P. asked whether “Apatosaurusminimus might not be a Apatosaurus specimen after all — particularly, an Apatosaurus ajax individual resembling NSMT-PV 20375, the one in the National Science Museum, Tokyo, that Upchurch et al. (2005) so lavishly monographed.

Initially, I dismissed this idea out of hand, because the “Apatosaurusminimus sacrum-pelvis complex is so very different to that of the “Brontosaurus” illustrated by Hatcher (1903: fig. 4), as seen in an earlier post. But on going back to the Upchurch et al. monograph I realised that their sacrum-ilium complex is very different from Hatcher’s. Here it is, cleaned up from scans and re-composed in the same format as the Camarasaurus and “Apatosaurusminimus from last time, for easy comparison.

Sacrum and fused ilia of Apatosaurus ajax NSMT-PV 20375. Top row: dorsal view with anterior to left. Middle row, left to right: anterior, right lateral (reversed), posterior. Bottom row: ventral view with anterior to left. Modified from Upchurch et al. (2005: plate 4 and text-figure 9).

Here’s Hatcher’s “Brontosaurus” illustration (from his plate 4) again:

I’m not sure what to make of this. The Tokyo Apatosaurus seems to be intermediate in some respects between Hatcher’s specimen and “Apatosaurusminimus.

One important difference is that the neural spines are much taller in Hatcher’s illustration than in the Tokyo Apatosaurus. Could that be ontogenetic? (IIRC the Tokyo individual is subadult). Or are they in fact different species? Or is it just individual variation?

I don’t know. Anyone?

References

  • Hatcher, J.B. 1903. Osteology of Haplocanthosaurus with description of a new species, and remarks on the probable habits of the Sauropoda and the age and origin of the Atlantosaurus beds; additional remarks on Diplodocus. Memoirs of the Carnegie Museum 2:1-75.
  • Upchurch, Paul, Yukimitsu Tomida, and Paul M. Barrett. 2005. A new specimen of Apatosaurus ajax (Sauropoda: Diplodocidae) from the Morrison Formation (Upper Jurassic) of Wyoming, USA. National Science Museum Monographs No.26. Tokyo.

 

Upchurch et al. (2005)

Thanks to the wonder of Osborn and Mook (1921), we have already seen multiview illustrations of the pubis and ischium of Camarasaurus. Now we bring you their Camarasaurus sacrum.

This is the sacrum of Camarasaurus supremus AMNH 5761. Top row: dorsal view, with anterior to left. Middle row, from left to right: anterior, left lateral and posterior views. Bottom row: ventral view, with anterior to left. Modified from Ostrom and Mook (1921:figs. 43-44).

It’s instructive to compare with the “Apatosaurusminimus sacrum. Direct comparison is somewhat hindered for two reasons: first, the ilia are fused to that sacrum but not to this; and second, different views are available, so I put the composites together differently. We can’t do anything about the ilia. But to facilitate comparison, here is a reworked version of the “Apatosaurusminimus illustration with the right-lateral view discarded, a ventral-view silhouette added, and the composition mirroring that of Osborn and Mook’s Camarasaurus:

One thing is for sure: whatever else “Apatosaurus” minimus might be, it ain’t Camarasaurus.

References