Monthly Archives: September 2023

A close encounter with an opossum

Last night I took some boxes out to our recycling bin, and as I was walking along the back fence I did a double-take — I’d walked within a couple of feet of this opossum before I knew it was there. It was so close that if I hadn’t been worried about either scaring it or getting bitten, I could easily have reached out and petted it like a cat. We both froze, and I whipped out my phone and started taking pictures.

The opossum was up on top of the fence, it couldn’t exactly flop down and play dead without risk of injury, but it did hold completely still for a minute or so while I experimented with different attempts at getting a good photo. I brightened up this second one a bit in GIMP. The opossum is in exactly the same pose as in the first photo, I just hadn’t stepped forward to get a better side view.

After getting a couple of passable photos, I decided to try shooting a video. That worked okay in terms of capture, although now I see that my dumb phone focused on the trees in the background instead of the awesome mammal in the foreground. When I started talking, the opossum decided it had had enough, and it scampered off along the fence.

I love opossums. Skeletally they look almost identical to mammals from the Early Cretaceous. For like 100 million years, there has been something approximately opossum-like rummaging around in nature’s back yard. And now they’re in my back yard. That’s cool.

 

doi:10.59350/d22qp-h0f62

The untold story of the Carnegie Diplodocus

My talk (Taylor et al. 2023) from this year’s SVPCA is up!

The talks were not recorded live. But while it was fresh in my mind, I did a screencast of my own, and posted it on YouTube (CC By).

For the conference, I spoke very quickly and omitted some details to squeeze it into a 15-minute slot. In this version, I go a bit slower and make some effort to ensure it’s intelligible to an intelligent layman. That’s why it runs 21 minutes. I hope you’ll find it worth your time.

References

  • Taylor, Michael P., Matthew C. Lamanna, Ilja Nieuwland, Amy C. Henrici, Linsly J. Church, Steven D. Sroka and Kenneth Carpenter. 2023. The untold story of the Carnegie Diplodocus. p. 31 in Anonymous (ed.), SVPCA 2023 Lincoln: the 69th Annual Symposium of Vertebrate Palaeontology and Comparative Anatomy. https://www.youtube.com/watch?v=BMGIacxCaaQ

 

doi:10.59350/wh5bs-20779

Giant titanosaurs were just ridiculous

Here’s Mike with the cast dorsal vertebra of Argentinosaurus that’s on display at the LACM. I tried to get myself equidistant from both Mike and the vert when I took the photo, but even I couldn’t quite believe it when I looked at it on my laptop. Surely, I thought, there must be some subtle foreshortening going on, to make the Argentinosaurus vert look bigger than it is. So I did some cypherin’.

The LACM dorsal has a clearly reconstructed centrum, and in all other ways, including the position of the parapophyses and the slightly reclined neural spine, it’s a good match for this vertebra figured in Bonaparte and Coria (1993: fig. 2). The scale bar there is 50cm. In my scan, it’s 242 pixels, and the total height of the vertebra is 800 pixels, or 1.65 meters, or 5’5″. Mike’s about 1.8 meters, and the photo confirms that he’s a little taller than the vertebra, but not by much. I think that photo is a pretty accurate representation of the size of the vertebra relative to a normal human being Mike.

Which is kinda crazy. I’m no stranger to big vertebrae — my first project turned out to be Sauroposeidon, and I’ve spent more time looking at Giraffatitan and Supersaurus verts than is probably healthy — but damn. Even I am used to big vertebrae that are still smaller than a person. Fair play to you, Argentinosaurus.

(I’m contractually obligated to remind everyone that despite frequent claims to the contrary, Argentinosaurus is still the largest dinosaur known from measurable bones.) 

Reference

Bonaparte, J.F. and Coria, R.A. 1993. Un nuevo y gigantesco saurópodo titanosaurio de la Formación Río Limay (Albiano-Cenomaniano) de la Provincia del Neuquén, Argentina. Ameghiniana 30(3):271-282.

 

doi:10.59350/faw7v-kwx03

Neck ontogeny in Tyrannosaurus rex, redux

Back into 2019, when Matt and I visited the Carnegie Museum, we were struck by how different the necks of juvenile and adult Tyrannosaurus rex individuals are. In particular, the juvenile individual known as Jane has a slender and amost fragile-looking neck compared with the monstrously robust neck of its adult counterpart.

A few weeks ago, Matt and I were at the Los Angeles County Museum (LACM), which has a superb tyrannosaur exhibit with three mounted skeletons at different growth stages:

Here it is from the opposite angle, taken from the balcony above the exhibit:

But what’s this we see in the tiny tyrannosaur that is the baby of the bunch?

A robust neck indeed — very much like that of the adult, and seemingly out of proportion with the slender skull. Let’s compare that once more with a similar shot of Jane the Carnegie juvenile:

(This is the same photo I used in the original post, but cropped a bit differently to better match the photo of the LACM baby.)

And remember: the LACM baby is smaller, and therefore we would assume younger, than Jane. Yet its neck is much, much more robust.

Once you have the two photos side by side, other differences are apparent — notably, that Jane’s forelimbs, scapulae and especially hands are proportionally much longer than in the LACM baby. In comparison, the LACM baby’s postcranium looks like that of a scaled-down adult.

What’s going on here?

If both of these skeletons are legitimate (i.e. mostly based on real fossil material of single individuals) then we have to be dealing with two different species here. There’s just no rational ontogenetic trajectory that goes from the LACM baby via Jane to the adult form.

On the other hand, maybe one or both of the juvenile skeletons is not really legitimate. I don’t know enough about tyrannosaurs to be familiar with individual specimens, but no doubt plenty of people out there are. (If any of them would like to comment here, that would be very welcome.)

I leave you with one more photo of that glorious three-tyrannosaur exhibit.

 

doi:10.59350/d3hb9-av191

Surprisingly decent retail anatomy

I popped into my local Michaels arts-n-crafts store today to see what Halloween goodies they had.

One trend I can definitely get behind is the rise of anatomical oddities and cabinets of curiosities as Halloween decor. A lot of what gets marketed in this space is not my thing, like decorative skulls with snakes or butterflies or whatever.

I don’t hate these; these days I have a hard time getting agitated about anything that brings someone else joy, as long as it’s not hurting anyone. And if you’re looking to decorate for Halloween, you could do a lot worse — these are at least recognizable human skulls, unlike the distorted frowny skulls that are supposed to look sinister but come off as clownish. But I’m after possibly-useful anatomical specimens, so I prefer skulls that are both realistic and unadorned.

Fortunately, there’s a rising-tide-floats-all-boats thing going on, and along with the more ornate varieties there are skulls done up as teaching aids, like these small ones that have the bones labeled.

Here’s a close-up. If I had my druthers, I’d prefer “maxilla” and “mandible” instead of “upper jaw bone” and “lower jaw bone”, especially alongside the old-timey term “malar”, which has been almost completely replaced by “zygomatic” in modern anatomical nomenclature.

Nevertheless, I liked these so much that I bought one and put it on a little stand in the living room.

Lurking on a bottom shelf I found even more realistic skulls — life-size, unlabeled, and I’m pretty sure nth-generation casts of a real male human skull.

As decor, these are a little less friendly and a little more sinister than the labeled teaching skulls. As things you could use to actually learn anatomy — not bad! I’m sure the basicranium is a mess where it’s glued to the wooden stand, but you could still use this thing to learn the bones, sutures, features, craniometric landmarks, and neurovascular foramina over most of the skull.

Over on the ‘Human anatomy study materials‘ sidebar page, you’ll find a bunch of “color your own skull” images, which I extracted from the 1917 public-domain Gray’s Anatomy and posted for students so they can draw on top of them. The drawings are useful but a real(ish) 3D skull is even better, especially if you can get one cheaply enough that you wouldn’t mind writing or drawing right on it. Or if you’re an artist who doesn’t care much if the carotid canals are visible, but just wants an acceptable skull for reference.

I’m sure you’ve experienced the holiday decor acceleration phenomenon, in which Christmas stuff starts showing up in certain retail hellholes right about now, when we’re technically still in summer. That’s gross, but it does have the benefit that as of this writing, still almost two months from Halloween, most of the Halloween stuff at my local Michaels is already on 40% discount, getting sold off cheap to make room for Thanksgiving and Christmas. The realistic skulls-on-stands originally sold for $25, at which price I might balk, but for $15 they seem like a steal. The little labeled teaching skulls are down to $12.

These x-ray candles are pretty cool, too.

Other than the skulls, I’m most excited about the glass domes. Those can be a pain to find, and expensive, but these are serviceable and inexpensive and right down the street from me.

I really wanted to love this little wooden cabinet of curiosities, but (1) the bat “skull” with bony ears gives me hives, (2) the rest of the stuff looks fine from about 10 feet away but doesn’t bear close inspection, and (3) everything is tacked down with immense, visible globs of glue. Still, if it’s your thing, go nuts. What I’d like Michaels to sell alongside this is an empty version, just the distressed wood display case without all the fake oddities, so I could fill it up myself (I have stuff). If anyone from Michaels is reading this, please pass that request on to management.

I can’t believe I’m posting about Halloween stuff at the end of the first week of September, but this stuff is on sale now and it seems to be going quickly — the glass dome selection is down to about a tenth of what it was last month. So if you have the opportunity and inclination, don’t tarry.

 

doi:10.59350/wyrjk-gv795