Sauropod Vertebra Picture of the Week

A couple of months ago, I asked for your help in compiling a list of all known complete sauropods necks. This has gone really well, and I want to thank everyone who chipped in, and all the various authors I have contacted for details as a result.

My next step is to take the raw data in the Google spreadsheet that I have been maintaining, and write it up as prose for the paper that I am shortly going to resubmit, having first done so back in 2015. And I thought it would make sense to draft that section here on SV-POW!, so I can get any further feedback before I finalize it for the manuscript.

Young and Zhao (1972:figure 3). Mamenchisaurus hochuanensis holotype CCG V 20401 as is occurred in the field.

So here goes: any additional comments at this stage will be welcome!

Unambiguously complete necks are known from published accounts of only a few sauropod specimens. In chronological order of description, the following specimens were found with their necks complete and articulated, and have been adequately described:

• CM 11338, a referred specimen of Camarasaurus lentus described by Gilmore (1925). This is a juvenile specimen, and thus does not fully represent the adult morphology. (McIntosh et al. 1996:76 claim that this specimen is the holotype, but this is not correct: YPM 1910 is the holotype — see below.)
• CM 3018, the holotype of Apatosaurus louisae, described by Gilmore (1936). The neck was separated from the torso but articulated from C1–C15, though the last three cervicals were badly crushed: see below for details.
• CCG V 20401, the Mamenchisaurus hochuanensis holotype, described by Young and Zhao (1972). Each vertebra is broken in half at mid-length, with the posterior part of each adhering to the anterior part of the its successor; and all the vertebrae are badly crushed in an oblique plane.
• ZDM T5402, a Shunosaurus lii referred specimen, described in Chinese by Zhang (1988), with English figure captions. Figure 22 depicts the atlas. Unlike the holotype T5401, this specimen is mature.
• BYU 9047, the Cathetosaurus lewisi holotype, described by Jensen (1988). (Jensen incorrectly gives the specimen number as BYU 974.) This specimen was redescribed, and the species referred to Camarasaurus, by McIntosh et al. (1996). Although all 12 cervicals are present, “10–12, particularly 12, have suffered such severe damage that it is impossible to restore them” (McIntosh et al. 1996:76).
• MACN-N 15, the holotype of Amargasaurus cazaui MACN-N 15, described by Salgado and Bonaparte (1991) who desribed “22 presacral vertebrae articulated with each other and attached to the skull and sacrum, relatively complete” (Salgado & Bonaparte 1991:335, translated.
• ZDM 0083, the holotype of Mamenchisaurus youngi, described in Chinese by Ouyang and Ye (2002) with English figure captions. Figure 14 depicts the atlas and axis.
• MUCPv-323, the holotype of Futalognkosaurus dukei, initially described by Calvo et al. 2007a and redescribed by Calvo et al. 2007b. The neck was found in two articulated sections which fit together without needing additional vertebrae in between (Jorge O. Calvo, pers. comm., 2021).
• SSV12001, the holotype of Xinjiangtitan shanshanesis, described by Zhang et al. (2018). The original description of this specimen by Wu et al. 2013 included only the last two cervicals, which were the only ones that had been excavated at that time.

A few additional specimens are known to have complete and articulated necks, but have not yet been described:

• USNM 13786, a referred subadult specimen of Camarasaurus lentus recently mounted at the Smithsonian. The specimen “was almost completely buried before the sinews had allowed the bones to separate” (letter from Earl Douglass to William J. Holland, 22 August 1918), and photographs kindly supplied by Andrew Moore show that the atlas was preserved.
• MNBH TIG3, the holotype of Jobaria tiguidensis. Sereno et al. (1999:1343) assert that this species has 12 cervicals in all and say “One articulated neck was preserved in a fully dorsiflexed, C-shaped posture”. Sereno (pers. comm., 2021) confirms that the articulated neck is MNBH TIG3
• SMA 002, referred to Camarasaurus sp. Tschopp et al. (2016), in a description of its feet, say that this specimen “lacks only the vomers, the splenial bones, the distal end of the tail, and one terminal phalanx of the right pes. The bones are preserved in three dimensions and in almost perfect articulation”.
• MAU-Pv-LI-595, the “La Invernada” Titanosaur. Filippi et al. (2016) give a very brief account in an abstract. Filippi, pers. comm, 2021) says that the entire preserved specimen was articulated.
• MAU-Pv-AC-01, an unnamed titanosaur mentioned in abstracts by Calvo et al. (1997) and Coria and Salgado (1999). The specimen was found in perfect articulation from skull down to the last caudal vertebrae (Rodolfo Coria, pers. comm., 2021).

The first cervical (the atlas) in sauropods is very different in form from the other vertebrae, and small and fragile. Consequently it is easily lost. Some further specimens have necks that are complete and articulated from C2 (the axis) backwards:

• MB.R.4886, the holotype of Dicraeosaurus hansemanni, described by Janensch (1929), has a neck that complete and well preserved from C2 to C12 (the last cervical). Janensch referred to this as “specimen m” and writes “It was found articulated from the 19th caudal vertebra to the 9th cervical vertebra inclusive. The proximal part of the neck from the 8th cervical vertebra up to the axis was bent ventrally and lay at right angles to the distal part of the neck.” (Janensch 1929:41).
• PMU 233, the holotype of Euhelopus zdanskyi, described by Wiman (1929) as “exemplar a” and redescribed by Wilson and Upchurch (2009).
• ZDM T5401, the subadult holoype of Shunosaurus lii, described in Chinese by Zhang et al 1984. The quarry map (Zhang et al. 1984:figure 1) suggests that the atlas is missing.
• MCT 1487-R, informally known as “DGM Series A”, described by Powell (2003). Gomani (2005:9) summarises as “12 cervical vertebrae, except the atlas, preserved in articulation with three proximal dorsal vertebrae”.
• GCP-CV-4229, the holotype of Spinophorosaurus nigerensis, described by Remes et al. (2009). The specimen was found in very good condition and well articulated from C2 to C13, the last cervical. The atlas seems to be missing (Remes, pers. comm., 2021.

One other sauropod is complete from the first cervical, but probably not to the last:

• MOZ-Pv1232, the holotype of Lavocatisaurus agrioensis, described by Canudo et al. (2018). This is complete from C1-C11. Canudo’s guess is that this is complete neck (Canudo, pers. comm, 2021), but the specimen doesn’t demand that conclusion and no known eusauropod has fewer than 12 cervicals.

Other sauropod specimens have necks that are complete and articulated from further back in the cervical sequence:

• YPM 1910, Camarasaurus lentus, a mounted specimen described by Lull (1930). The neck is complete from C2 or C3, Lull was uncertain which.
• SMA 0004, Kaatedocus siberi, described by Tschopp and Mateus (2012). Cervicals 3-14 are preserved.
• AODF 888 (informally “Judy”), probably referrable to Diamantinasaurus, briefly described by Poropat et al. (2019). Preserved from C3 or maybe C4. “One posterior cervical (XIII or XIV) found several metres from articulated series, but appears to slot nicely into the gap between the articulated cervical series and the unprepared thoracic section, which might include at least one additional cervical (XIV or XV)” (Poropat, pers. comm. 2021).

Several necks are probably nearly complete, but it is not possible to knew due to their not being found in articulation:

• CM 84, the holotype of Diplodocus carnegii, described by Hatcher (1901). C2–C15 are preserved, though not all in articulation; C11 may be an intrusion: see below for details.
• ZDM T5701, the holotype of Omeisaurus tianfuensis, described by He et al. (1988). The neck was not articulated (He et al. 1988:figure 1), and was missing “two elements or so” (He et al. 1988:120).
• QJGPM 1001, the holotype of Qijianglong guokr, described by Xing et al. (2015). On page 8, the authors say “The axis to the 11th cervical vertebra were fully articulated in the quarry. The atlas intercentrum and the 12th–17th cervical vertebrae were closely associated with the series.”
• MNBH TIG9, a referred specimen of Jobaria tiguidensis. Wilson (2012:103) writes that this specimen “includes a partially articulated series of 19 vertebrae starting from the axis and extending through the mid-dorsal vertebrae.”
• MNBH TIG6, another referred specimen of Jobaria tiguidensus, which has not been mentioned in the literature. Sereno (pers. comm., 2021) says that it is “a subadult partial skeleton with excellent neck” and that “the sequence was articulated from C2–11. Most of the ribs were attached as well.”

At the time of writing, the Paleobiology Database (https://paleobiodb.org/) lists more than 270 sauropod species. The nine unambigously complete and articulated necks therefore represent only one in 30 known sauropod species.

Note. The Jobaria tiguidensis individuals previously had specimen numbers beginning MNN, but the Musee National du Niger changed its name to Musée National Boubou Hama and the specimen numbers have changed with it.