What’s up with your perforated parapophyseal ramus, Apatosaurinae indet. BYU 20178? — Featuring: What have we learned?

I happened to be reading back over Tutorial 34: How to document a specimen, when something caught my eye in the example photo we used of how to capture the label and appropriately positioned scalebar along with the specimen:

Somehow, when I wrote that post, I didn’t actually look at the photo I was showing you all as an example of How To Do It Right. And, worse, I ignored my own advice from the same tutorial: to actually look at the damned specimen while you’re right there with it.

If I’d done either, I would have noticed that the left parapophyseal ramus (at the top of the photo, supporting the cervical rib) has a whacking great hole in it. Here you go, in close-up.

Infuriatingly, it’s one of only three photos I took of this specimen (it was during the Sauropocalypse of 2019), and the only one in ventral view.

BUT! Check out this posterior view, which is one of the other two photos. (The third is useless for our present purposes.)

From this angle, it looks like a perfectly respectable apatosaurine cervical. Could it be that the parapophyseal ramus, facing us edge-on at top right in the photo, is just not displaying the perforation from this angle?

I dont think so: there is a distinctive pattern of cracks in  the posterior face of the diapophyseal ramus, which you can see in both photos, and which I’m highlighting here in red here:

And here:

What appeared in the first photo to be the part of the parapohyseal ramus with those cracks is now seen to be diapophyseal. And that original photo up at the top doesn’t show a perforation at all, just an oblique view of the cervical rib loop. It looks like a perforation because from that one angle the parapophyseal ramus perfectly overlays the diapophyseal. But now we know what we’re looking for, we can see where the overlap is.

Here’s that first photo again with the overlap emphasized by adding a fake shadow:

What have we learned?

First, we’ve learned that nothing is up with the unperforated parapophyseal ramus of Apatosaurinae indet. BYU 20178. It can go about its business.

But there is a broader lesson here, about looking a photos of complex three-dimensional objects, especially when they also have complex surface textures. By all means, look at such photos and enjoy them — but be very careful about drawing conclusions from them in isolation. They can be terribly misleading.

So misleading that when I laid down the first sketch of this post, it really was going to be about the osteological novelty of the perforation. I’m laying my card on the table here, I’m dumbass enough to have walked right into the trap I’m warning about. The only thing that saved me was a trivial wrinkle of my method, which I’m going to share now in the hope that it helps. Here it is:

When I prepare an image for use in the blog, I don’t rename it from the camera’s uninformative name IMG_3527.JPG to something like BYU-20178–apatosaurine-cervical–ventral.JPG. No, instead I rename it pedantically to a filename that also retains the camera’s originally allocated filename — in this case, IMG_3527–BYU-20178–apatosaurine-cervical–ventral.JPG.

Why does that help? Because it meant that when I returned to this draft post long after that first sketch, I was able to see that image number 3527, locate the original IMG_3527, and see that I had IMG_3528 right next to it — and that photo had the critical posterior view.

This probably seems like a very little thing; but it’s helped me many, many times over the years. Not only in blogging, either, but in figure preparation for formal publications. When I make a multiview like the apatosaur cervical that’s Figure 6 of Wedel and Taylor (2023) on bifurcated cervical ribs, the layers aren’t just named things like anterior and ventral, but IMG_6735 anterior.That means if I need to check my interpretation of part of the figure, I can find the other photos I took around the same time to compare with.

I recommend it.

References

• Wedel, Mathew J., and Michael P. Taylor. 2023. The biomechanical significance of bifurcated cervical ribs in apatosaurine sauropods. VAMP (Vertebrate Anatomy Morphology Palaeontology) 11:91-100. doi: 10.18435/vamp29394

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doi:10.59350/37nhm-hhq17

Source: https://svpow.com/2024/11/30/whats-up-with-your-perforated-parapophyseal-ramus-apatosaurinae-indet-byu-20178-featuring-what-have-we-learned/