Sauropod Vertebra Picture of the Week

One of our great palaeontological heroes (well, one of mine anyway) is Charles Whitney Gilmore (1874-1945), former curator of the Division of Vertebrate Paleontology at the United States National Museum (USNM), successful monographer of stegosaurs, ornithopods and theropods, and prolific describer of ceratopsians, crocodilians, ichthyosaurs… and sauropods. But like oh so many late great palaeontologists, I previously had no idea what he looked like and had never seen a photo of him. Well, here he is and, to boot, he’s posing with some sauropod vertebrae: specifically, caudals of Diplodocus.

Gilmore named one of the best known of titanosaurs, Alamosaurus, in 1922, and in 1932 described a Diplodocus specimen collected from Uinta County, Utah, in 1924 and mounted in the USNM eight years later (it is specimen USNM 10865). After comparing the four Diplodocus species (D. longus Marsh, 1878, D. lacustris Marsh, 1884, D. carnegii Hatcher, 1901 and D. hayi Holland, 1924) Gilmore (1932) concluded that USNM 10865 couldn’t be referred to any one ‘until there has been a thorough revision of the genus’ (p. 7). You might recall that we looked at Diplodocus caudal vertebrae quite recently, and on that occasion the vertebrae belonged to D. carnegii. If you compare the D. carnegii caudals with the USNM 10865 vertebrae shown in the photo above, you’ll note that the neural spines of the CM 84 D. carnegii specimen appear more posteriorly inclined than do those on USNM 10865.

As Gilmore explained, D. carnegii has more inclined neural spines than D. longus, so perhaps USNM 10865 is a D. longus (you can clearly see the different neural spine orientations depicted in Scott Hartman’s skeletal reconstructions of D. carnegii and D. longus in Lovelace et al.’s (2007) recent Supersaurus paper, shown below: click to enlarge. Image copyright Scott Hartman). However, Gilmore also noted that some of the USNM neural spines are posteriorly inclined, and as much as are those of D. carnegii. He ended up labelling the specimen D. longus, and this is what it remains today, but further study is needed…. in fact, we probably need a good, specimen-level analysis of the different alleged Diplodocus species. Upchurch et al. (2004) recently did exactly this with Apatosaurus.

Anyway, the photo used above comes from here on Shorpy, the ‘100-year-old photo blog’, and thanks to both George Hammond and Jacob Kesinger for bringing it to our attention – it’s a nice one to have added to the site. Palaeo-mammal fans might note the panel-mounted Phenacodus on the wall.

References

• Gilmore, C. W. 1932. On a newly mounted skeleton of Diplodocus in the United States National Museum. Proceedings of the United States National Museum 81, 1-21.
• Lovelace, D. M., Hartman, S. A. & Wahl, W. R. 2007. Morphology of a specimen of Supersaurus (Dinosauria, Sauropoda) from the Morrison Formation of Wyoming, and a re-evaluation of diplodocid phylogeny. Arquivos do Museu Nacional, Rio de Janeiro 65, 527-544.
• Upchurch, P., Tomida, Y. & Barrett, P. M. 2004. A new specimen of Apatosaurus ajax (Sauropoda: Diplodocidae) from the Morrison Formation (Upper Jurassic) of Wyoming, USA. National Science Museum Monographs 26, 1-108.