Nigersaurus in the mist
February 28, 2024
The best thing about collaborations is that I get to work with amazing colleagues from around the world. The second-best thing about collaborations is that I get to work on badass critters that I wouldn’t otherwise have access to, like sick* diplodocids, tiny saltasaurines, Triassic barely-dinosaurs, and — most recently — my first rebbachisaur (Windholz et al. 2024). I’d seen rebbachisaurs firsthand before, in a traveling exhibit and on the Isle of Wight — plus Xenoposeidon in the NHM collections (in 2005, well before NHMUK PV R2095 became Xeno) and secondhand in plastic — but this was my first time getting to work on one.
*Sick meaning ‘crazy cool‘ and also ‘hideously diseased‘.
I celebrated my advent as a rebbachisaur worker by treating myself to the Jurassic World Wild Roar Nigersaurus, which AFAIK is the only rebbachisaur to have yet been incarnated in toy form. There have been other, and frankly much more accurate, Nigersaurus toys (= figures) produced before — in particular, the duckbill-face on the JW Nigersaurus is less weird and extreme than Nigersaurus’s actual face — but I believe the JW Nigersaurus is the only one that makes noise.
Shortly after I got the JW Nigersaurus, we got a delivery of cold stuff, and I had some dry ice to play with. You know how that story ends.
Sadly, I didn’t think to put the plant in the mist until I had too little dry ice left to make a convincing fog. Until next time…
Reference
A bite-marked Apatosaurus pubis, in bone and in bronze
February 23, 2024
MWC 861 in bone (left) and in bronze (right).
Here’s a cool comparo. I was on the road recently, and since I was passing through Fruita, Colorado, I got some photos of my old friends MWC 861 and MWC 4011, a pubis and ischium, respectively, of Apatosaurus, with deep bite marks on their distal ends from a big theropod, probably Allosaurus (you may remember these awesome specimens from previous posts). That’s MWC 861 above on the left.
A week later I was passing through Tucumcari, New Mexico, and I decided it was finally time I stopped in at the Mesalands Dinosaur Museum, whose billboards I’d seen along I-40 numerous times on drives between SoCal and Oklahoma. Mesalands Dinosaur Museum is run by Mesalands Community College, which has a metalworking program and a bronze foundry. Evidently a lot of students cast fossils in bronze, and a good chunk of the museum exhibits are made of bronze — including the cast of MWC 861 above on the right.
This is the appropriate reaction to putting your grubby mitts on real sauropod bones that were really bitten by real theropods.
Why is my big dumb hand in the photos? When our theropod bite mark paper came out last fall (Lei et al. 2023), it stirred up some media interest, and one request I was not prepared for was for photos of the bite marks with a hand in for scale. I had a few, mostly of CM 555 (you can see those here), but to my immense irritation, I’d never taken any photos of the much-more-impressive MWC 861 and MWC 4011 with my hands in the shots for scale. I’ve now rectified that oversight.
Incidentally, Gaston Design sells casts of the ischium, MWC 4011, both the whole bone and just the bitten distal end. I picked up one of the latter while passing through Fruita. Do not judge Rob Gaston’s work by this particular cast, which is unfinished. Rob warned me in advance that he hadn’t time to finish the painting and antiquing, but I could have the cast anyway if I was interested. He also gave me a ton of advice on how to finish it myself, which I will be attempting in the future. In the meantime, yay! New toy!
So if you’re driving through Colorado on I-70, stop in Dinosaur Journey to see and touch some pretty amazing specimens. And if you’re driving through New Mexico on I-40, stop in the Mesalands Dinosaur Museum and do the same.
Reference
New paper: pneumaticity in a rebbachisaurid caudal vertebra
February 15, 2024
Fig. 2. Rebbachisauridae indet. (MDPA-Pv 007) from the Sierra Chata locality (Candeleros Formation) Cenomanian (Upper Cretaceous). Anterior caudal vertebra in anterior (A1, A3), posterior (A4, A6), and left lateral (A7, A9) views. Close ups showing lateral spinal laminae (A2), accessory bony lamina located inside of spof (A5), foramina in the lateral surface of the centrum, arrowheads indicate the presence of foramina (A8). Abbreviations: acdl, anterior centrodiapophyseal lamina; amedl, anterior medial lamina; cdf, centrodiapophyseal fossa; cpol, centropostzygapophyseal lamina; cprl, centroprezygapophyseal laminae; nc, neural canal; pcdl, posterior centrodiapophyseal lamina; pmedl, posterior medial lamina; pocdf, postzygapophyseal centrodiapophyseal fossa; pocdf-l, postzygapophyseal centrodiapophyseal fossa lamina; posdf, postzygapophyseal spinodiapophyseal fossa; prcdf, prezygapophyseal centrodiapophyseal fossa; prcdf-l, prezygapophyseal centrodiapophyseal fossa lamina; prdl, prezygodiapophyseal lamina; prsdf, prezygapophyseal spinodiapophyseal fossa; pz, postzygapophyses; spof, spinopostzygapophyseal fossa; spdl, spinodiapophyseal lamina; spol-f, spinopostzygapophyseal lamina fossa; sprl, spinoprezygapophyseal laminae; sprl-f, spinoprezygapophyseal lamina fossa. Windholz et al. (2024: fig. 2).
I have a new paper out in Acta Paleontologica Polonica, with Guillermo Windholz, Juan Porfiri, Domenica Dos Santos, and Flavio Bellardini, on the first CT scan of a pneumatic caudal vertebra of a rebbachisaurid:
This will be a short post because I’m on the road right now, but I’m pretty darned happy about this paper. Like many of my recent publications, this is primarily a descriptive paper, but with interesting implications.
Drawings of an Isle of Wight rebbachisaurid anterior caudal vertebra (MIWG 5384). A, anterior view; B, right lateral view; C, posterior view. Scale bar represents 200 mm. Mannion et al. (2011: fig. 2).
I’ve been interested in caudal pneumaticity in rebbachisaurids for a long time. As far as I can remember, the first paper that clued me in on the subject was Mannion et al. (2011), on Early Cretaceous rebbachisaurid material from the Isle of Wight. The deep, subdivided, often asymmetric fossae on the neural spines and transverse processes showed that at least some rebbachisaurids evolved caudal pneumaticity comparable to that of diplodocids. I’ve been wanting to see CT scans of a rebbachisaurid caudal ever since, and last summer, Guillermo Windholz wrote to offer me that very opportunity.
Fig. 4. Selected computed tomographic sections of Rebbachisauridae indet. (MDPA-Pv 007) from the Sierra Chata locality (Candeleros Formation) Cenomanian (Upper Cretaceous). Vertebra in anterior view (A1), transverse section taken at mid-length of the element (A2), parasagittal section (A3), frontal sections (A4–A10). Abbreviations: cdf, centrodiapophyseal fossa; nc, neural canal; pocdf, postzygapophyseal centrodiapophyseal fossa; prcdf, prezygapophyseal centrodiapophyseal fossa; spol-f, spinopostzygapophyseal lamina fossa; sprl-f, spinoprezygapophyseal lamina fossa. Windholz et al. (2024: fig. 4).
The scans are beautiful, but the revealed anatomy is wacky. The neural spine and transverse processes are shown to be formed of thin, intersecting laminae that bound deep fossae, which is always cool to see but also expected at this point — Osborn figured similarly-excavated neural spine cross-sections from Diplodocus back in 1899. Internally, the centrum shows a network of large, interconnected chambers, but the internal structure is wildly asymmetric. This is particularly evident in parts A2 and A10 of Figure 4, shown above.
So what’s going on here? Why is pneumatization of the neural spine and transverse processes so complete, while pneumatization of the centrum is so haphazard? I’m a big fan of asymmetric pneumatization, but this is ridiculous. And the bottom half of the centrum is basically a brick, in stark contrast to the extensive pneumatization of the upper works. I have some thoughts on this, but they’ll keep for a future post.
Also worth noting: although CT scanning fossils is becoming so common that it’s almost de rigueur these days, our global pool of CT-scanned sauropod vertebrae is tiny. Most of what we think we know — what I think I know, what I’ve built a good chunk of my career on — is connecting some very widely-spaced dots. Until last year, in all of human history we’d not managed to scan a single pneumatic caudal of a rebbachisaurid. Now we’ve scanned exactly one — which AFAIK is one more than the number of scanned vertebrae of any kind from Barosaurus, to pick an example at random. I wonder how much we’ll have learned when that number (in either category, Barosaurus vertebrae or rebbachisaurid caudals) is 5, or 10, or 50?
References
- Mannion PD, Upchurch P, Hutt S (2011) New rebbachisaurid (Dinosauria: Sauropoda) material from the Wessex Formation (Barremian, Early Cretaceous), Isle of Wight, United Kingdom. Cretaceous Research 32(6): 774–780.
- Osborn, H. F. 1899. A skeleton of Diplodocus. Memoirs of the American Museum of Natural History 1:191–214.
- Windholz, G.J., Porfiri, J.D., Dos Santos, D., Bellardini, F., and Wedel, M.J. 2024. A well-preserved vertebra provides new insights into rebbachisaurid sauropod caudal anatomical and pneumatic features. Acta Palaeontologica Polonica 69(1):39-47. doi: 10.4202/app.01104.2023
Sauropod Vertebra Picture of the Week 
