Here we are, already through January of 2024, and clearly we are not starting out like 2023, where the entire month had nary a new dinosaur. Today's entrant was the third of five announced in January 2024 (a couple of weeks ago, actually). You may notice the question mark in the post title; although described as a basal titanosaurian, Gandititan cavocaudatus fits a certain "type" of sauropod (mid-Cretaceous East Asian titanosauriform) that delights in phylogenetic instability. This to me is a subtle signal that something is going on we don't understand yet, so I'd best hedge my bets. So, maybe it's a titanosaur, maybe it isn't, but at any rate it's worth an introduction.
Genus and Species: Gandititan cavocaudatus. The genus name is multilayered. "Gan" refers to Ganzhou City and "di" "is the Chinese pinyin word for the Earth and is also the first syllable of 'dizhi', meaning 'geology'", with the whole intended to honor "geologic work in Ganzhou City". "Titan", of course, means "titan", and goes with sauropod theme naming. The species name is a combination of the Latin words for "cavity" and "tail", referring to the "complicated pattern of pleurocoels and neural arch laminae seen in the anterior caudal vertebrae". The intended translation is "cavity tailed" (Han et al. 2024).
Citation: Han, F., L. Yang, F. Lou, C. Sullivan, X. Xu, W. Qiu, H. Liu, J. Yu, R. Wu, Y. Ke, M. Xu, J. Hu, and P. Lu. 2024. A new titanosaurian sauropod, Gandititan cavocaudatus gen. et sp. nov., from the Late Cretaceous of southern China, Journal of Systematic Palaeontology 22(1): 2293038. doi: https://doi.org/10.1080/14772019.2023.2293038.
Geography and Stratigraphy: The type and only known specimen of G. cavocaudatus comes from "100 m north of Shiziyan Road, Datankeng, Ganxian District, Ganzhou City, Jiangxi Province, China", in rocks of the lower Upper Cretaceous Zhoutian Formation (Han et al. 2024).
Holotype: JXGM-F-V1 (Jiangxi Geological Museum, Jiangxi), which consists mostly of vertebrae: six articulated middle–posterior cervicals with fused ribs, two articulated dorsals, two partial dorsal ribs, and six articulated sacrals and 17 caudals plus the right ilium and chunks of the corresponding pubis and ischium (Han et al. 2024).
The type specimen was found as, essentially, the sacral–caudal segment and the cervical segment, in close association, preserved as aesthetically pleasing off-white bones in a much darker matrix. Enough was present for Han et al. to make an informed estimate of 14 m (46 ft) for the individual's length, so we're dealing with a roughly medium-sized titanosaur or titanosaur relative. The neural arches are fused (Han et al. 2024), so this is probably reasonably close to adult size as well.
The preserved cervicals come from around the middle to base of the neck, and are somewhat elongate. The neural spines are somewhat triangular in profile, becoming taller up-down and shorter fore-aft going back, as well as angling more anteriorly. The spines are also bifurcated (split longitudinally), which is uncommon for titanosaurs. The cervical ribs are fused to their vertebrae and not unusually long. The two dorsals are not in sequence with either the cervical or sacral–caudal segment, but represent something in the middle or posterior dorsal sequence. They are only partially preserved. The left side of the sacrum is eroded, and the right side is fused to the ilium. The neural spines of the sacrals are fused into a continuous "platform". Unlike traditional titanosaurs, the caudals are opisthocoelous rather than procoelous, and the neural arches are close to the same length as their centra rather than distinctly cheated forward. The caudals look rather chunky and squared-off. Unusually, the anterior caudal neural spines are also bifurcated (Han et al. 2024).
Han et al. include a comparison of G. cavocaudatus to other titanosauriforms from the Cretaceous of East Asia, the kind of thing that would have been nice in some other recent titanosaur publications. (Qinlingosaurus luonanensis is overlooked, but to be fair, everyone overlooks it.) They also include a new phylogeny, which finds G. cavocaudatus to be closest to Abdarainurus barsboldi in a basal titanosaur clade also including Baotianmansaurus henanensis, Dongyangosaurus sinensis, Huabeisaurus allocotus, and, strangely enough, Andesaurus delgadoi. Diamantinasaurs turn up just outside of Titanosauria, and a couple of recently featured names, Jiangxititan ganzhouensis and Ruixinia zhangi, are farther outside, which just goes to show the value of prudence when these darn things are playing coy.
References
Han, F., L. Yang, F. Lou, C. Sullivan, X. Xu, W. Qiu, H. Liu, J. Yu, R. Wu, Y. Ke, M. Xu, J. Hu, and P. Lu. 2024. A new titanosaurian sauropod, Gandititan cavocaudatus gen. et sp. nov., from the Late Cretaceous of southern China, Journal of Systematic Palaeontology 22(1): 2293038. doi: https://doi.org/10.1080/14772019.2023.2293038.
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