Xinjiangtitan has the longest preserved neck of any lifeform to date

January 28, 2021

Xinjiangtitan when originally described, from Wu et al. (2013)

We’re way late to this party, but better late than never I guess. Wu et al. (2013) described Xinjiangtitan shanshanesis as a new mamenchisaurid from the Middle Jurassic of China. At the time of the initial description, all of the dorsal and sacral vertebrae had been uncovered, as well as a handful of the most posterior cervicals and most anterior caudals.

Xinjiangtitan revealed, from Zhang et al. (2018)

Jump a few years forward 2018, when Zhang et al. described the complete cervical series of Xinjiangtitan, based on further excavation of the holotype (they also changed some of the element identifications in the original description). It’s pretty insane: 

  • 18 cervical vertebrae, same as Mamenchisaurus youngi, and one less than M. hochuanensis, all discovered in articulation;
  • 10 of those vertebrae have centrum lengths of 1 meter or more;
  • the longest centrum, that of C12, is 123cm long;
  • the total lengths of the separate cervical vertebrae (not articulated) add up to about 15 meters;
  • even assuming that the condyles of the vertebrae were fully buried in the cotyles, the total length of articulated neck would still be 13.36 meters. 

Now, some caveating. Zhang et al. (2018) report two different lengths for most the cervicals: a maximum centrum length, which includes the anterior condyle, and a “minimum centrum length” without the anterior condyle. Reporting cervical lengths minus the condyle is fairly common–Janensch did it for what is now Giraffatitan (“ohne condylus”), McIntosh (2005) did it for the AMNH Barosaurus, Tschopp and Mateus (2017) did it for Galeamopus pabsti, and so on. In the freely available but as-yet-not-formally-published 4th chapter of my dissertation (Wedel 2007), I referred to the length without the condyle as the “functional length”, and I explicitly assumed that it was “the length that each vertebra contributes to the total neck length”. At the time I assumed that condyles were always fully buried in cotyles in life, because I didn’t know about camel necks (see Taylor and Wedel 2013b: fig. 21 and this post). 

Why am I bringing up all these minutiae? Because I’m really interested in the actual length of the neck of Xinjiangtitan in life, and that’s not so very straightforward to figure out. I’ll start with what Zhang et al. wrote, then proceed to their measurements, and then discuss their map.

At the start of the Description section, Zhang et al. (2018: p. 3) wrote:

In SSV12001, the cervical series is almost completely articulated and is exposed laterally (Figure 2). The long neck (at least 14.9 m) is well-preserved with a total of 18 cervical vertebrae. This measurement was estimated based on the maximum centrum length including the anterior condyles with the space for the cartilage assumed.

How much space is assumed for the cartilage? They don’t say, and it’s not clear, but one reading is that they just added up the total lengths of all the cervical centra and assumed that the cotyles were completely full of cartilage. Which is not so crazy as it might sound, since that’s exactly what happens in camels. But let’s see what their tables of measurements say.

Xinjiangtitan cervical vertebra measurements, from Zhang et al. (2018)

Table 1 gives the measurements of the atlas and axis, and Table 2 gives the measurements of all the remaining cervicals. Only “minimum centrum length”–without the condyle–is reported for cervicals 4 and 5, because C3-C5 were articulated as a unit, they haven’t been separated, and without CT scanning or further prep it’s going to be impossible to determine how long they were with the condyles. However, we can infer that the condyles of C4 and C5 are buried in the cotyles of C3 and C4 because (a) only the without-condyle lengths are reported, and (b) the condyles aren’t visible in the figures. File that away, it’s going to be important.

Adding up all of the max centrum lengths, including 165mm for the axis and 30mm for the atlas, per Table 1, I get a total of 14985mm, or 14.985 meters. Because Zhang et al. were so assiduous about their reporting–they really did Measure Their Damn Dinosaur–we can estimate pretty closely how much longer that total would be if it included the condyles of C4 and C5. Subtracting the min length from the max length, we find that the condyle is 70mm long in both C3 and C6, so it’s reasonable to assume the same for the vertebrae in the middle. Adding 140mm to the earlier total gets us up to 15125mm, or 15.125 meters. That’s assuming condyles end even with the rims of the cotyles, and cotyles are completely full of cartilage.

Xinjiangtitan cervicals, from Zhang et al. (2018: fig 3)

Adding up the all of the minimum centrum lengths, again including the axis and atlas, yields a total of 13360mm, or 13.36 meters. I think this smaller total is much more likely to be the actual length of the neck in life, for three reasons:

  1. As mentioned above, the condyles of C4 and C5 of this very specimen are actually buried in the cotyles of the preceding vertebrae. So we don’t need to add any space for cartilage to the summed minimum (without condyle) lengths–there certainly was cartilage between the surfaces of the condyles and cotyles, because that’s how intervertebral joints work, but there was not enough to push the condyles back outside the cotyles, unless we want to engage in some special pleading that C3-C5 were unnaturally smooshed together.
  2. Camels notwithstanding, having the condyles buried in the cotyles is pretty standard for articulated necks of big, long-necked sauropods. In the holotype specimens of Mamenchisaurus hochuanensis and Sauroposeidon, the condyles are not visible in lateral view, because they are completely buried in the cotyles of the preceding vertebrae–see the photos in this post and on this page to confirm that for yourself. In Giraffatitan, just the edges of the condyles are visible sticking out the backs of the cotyles in some of the posterior cervicals–see this post.
  3. The 13.36-meter neck is more consistent with the map of the specimen in the ground than either the 14.9-meter or 15.1-meter totals.

A little unpacking on that last point. Using the dorsal lengths from Wu et al. (2013: table 1)–and assuming that Zhang et al. are correct, and the D1 of Wu et al. is actually cervical 18, but D11 of Wu et al. is actually D10 and D11 together, so there are still 12 dorsals–I get a total length for the articulated dorsal column of 3355mm. Dividing 13360 by 3355 yields a cervical/dorsal ratio of 3.98. Using the screenshot of the map from Zhang et al. (2018: fig. 2), I measured 1505 pixels for the summed cervicals, 380 pixels for the summed dorsals, and 112 pixels for the scale bar. Assuming the scale bar is supposed to be 1 meter (and not 20 meters or 2.0 meters as it is labeled) yields a summed cervical length of 13.4 meters, a summed dorsal length of 3.39 meters, and a cervical/dorsal ratio of 3.96–all admirably close, off by no more than 4cm across 16+ meters, if the neck in the ground was articulated condyle-inside-cotyle. If we assume the map shows a 14.9-meter neck, then both the dorsal series and the scale bar are off by about 12%, which is unreasonable given the high precision of the map if the articulated neck corresponds to the summed minimum lengths.

Mounted skeleton of Omeisaurus tianfuensis: N E C C

Bonus observation #1: the holotype of Mamenchisaurus hochuanensis has a cervical/dorsal ratio of 3.52, but in Omeisaurus tianfuensis the same ratio is 4.09. So Xinjiangtitan is actually a little shorter-necked than Omeisaurus, at least compared to the length of the dorsal series.

Bonus observation #2: the 123-cm cervical of Xinjiangtitan is only the fifth-longest vertebra of anything to date:

  1. BYU 9024, possibly referable to Supersaurus or Barosaurus: 137cm
  2. Price River 2 titanosauriform: 129cm
  3. OMNH 53062, Sauroposeidon holotype: 125cm
  4. KLR1508-77-2, Ruyangosaurus giganteus referred specimen: 124cm
  5. SSV12001, Xinjiangtitan shanshanesis holotype: 123cm
  6. MPEF-PV 3400/3, Patagotitan holotype: 120cm (+?)
  7. MPM 10002, Puertasaurus holotype: 118cm

Getting pretty crowded there in the 120s, but then a big jump to BYU 9024. I’ll have more to say on that in a second.

Just to put a bow on this section, I’m pretty confident, based on all available measurements, taphonomic evidence, and the consilience between the measurements and the map, that the holotype individual of Xinjiantitan had a neck 13.36 meters (43 feet, 10 inches) long in life. 

That’s stunning.

By comparison, the second- and third-longest complete cervical series (of anything, ever, to date) belong to Mamenchisaurus hochuanensis, at 9.5 meters (Young and Zhao 1972, and confirmed by Mike in a basement in Slovenia), and Giraffatitan at 8.5 meters for MB.R.2181 (the larger XV2 specimen would have had a 9.6-meter neck).

Some other contenders, from Taylor and Wedel 2013a (fig 3)

There were things with longer necks, for sure, but none of those necks are complete (yet). Mamenchisaurus sinocanadorum is estimated to have had a neck about 12 meters long, based on the partial cervical series of the holotype. I know there are skeletal reconstructions out there with longer necks, and I will believe them as soon as the specimens they are based on are published. In the aforementioned dissertation chapter, I estimated 11.5 meters for the neck of Sauroposeidon, assuming a brachiosaurid-like cervical count of 13. Note that Mannion et al. (2013) recovered Sauroposeidon as a somphospondyl, and a cervical count of 15 or more as a synapomorphy of Somphospondyli. Adding a couple more 1.2-meter mid-cervicals would bring Sauroposeidon up to perhaps 14 meters. The longest cervicals of Patagotitan are in about the same size class, and we don’t know the cervical count in that monster, either.

BYU 9024, with the mounted (cast, composite) skeleton of Brachiosaurus altithorax and one Mike Taylor for scale

And of course, lurking out there in crazy neck-space is BYU 9024, the immense cervical originally referred to Supersaurus, but which more likely belongs to Barosaurus, and an ungodly huge one. That critter might–might–have had a 17-meter neck.

And I gotta say, in light of Xinjiangtitan, that no longer seems so unreasonable. Because Xinjiangtitan was a big sauropod but not a monster. The dorsal length of 3.3 meters and the femur length of 1.65 meters put it in roughly the same size category as the bigger individual of Jobaria (DL 3.2m, FL 1.8m) or the AMNH 5761 Camarasaurus supremus (DL 2.5m, FL 1.8m). Let’s imagine a Xinjiangtitan with a 2.4-meter femur, the size of Patagotitan or Argentinosaurus. Assuming isometric scaling, that individual would have a 2.4/1.65 = 1.45 x 13.36 = 19.4-meter neck. 

Do we really think such animals never existed?

Food for thought: the holotype individual of Xinjiangtitan was small enough to be buried as a complete skeleton. What about the individuals that were too big to bury in one shot?

Utterly unsurprising, but still nice to see: the highly pneumatic internal structure of the vertebrae of Xinjiangtitan, from Wu et al. (2013)


20 Responses to “Xinjiangtitan has the longest preserved neck of any lifeform to date”

  1. Tom Says:

    Wow, that’s insane. A neck longer than the whole T. rex :-)

  2. Good point about the maximum vs. functional length distinction—I had taken the 14.9-meter estimate at face value when I first read the paper. Still a pretty wild neck either way, that’s for sure.

    “Food for thought: the holotype individual of Xinjiangtitan was small enough to be buried as a complete skeleton. What about the individuals that were too big to bury in one shot?”
    This question brings to mind Fushanosaurus. It’s known from only a femur and was originally described as a titanosauriform, but I don’t really see what makes it more likely to be a titanosauriform than a mamenchisaurid, especially given that mamenchisaurids are a good deal more common in Jurassic China. Its femur is 180 cm—if it had the same proportions as Xinjiangtitan, taking the minimal-cartilage estimate, its neck would’ve been 14.6 meters.

    Regarding the neck length of Sauroposeidon, the increased cervical counts of somphospondylans are dependent on Euhelopus and Dongbeititan being somphospondylans. If they’re mamenchisaurids as recently argued by Moore et al. 2020 (doi: 10.1080/14772019.2020.1759706) a standard 13 cervicals might be more plausible.

    Has anyone noticed the irony that Mamenchisaurus seems to be relatively short-necked by mamenchisaur standards?

  3. Allen Hazen Says:

    Elasmosaurs are much smaller, and not functionally comparable, but approach this critter in the matter of having a neck longer than the torso!

  4. Matt Wedel Says:

    Swans are smaller still, and they might even beat elasmosaurs. See the mounted swan skeleton in this post.

    Has anyone actually run the numbers, I wonder?

  5. Mickey Mortimer Says:

    “Has anyone noticed the irony that Mamenchisaurus seems to be relatively short-necked by mamenchisaur standards?”

    Ah, but what is and isn’t Mamenchisaurus? The type M. constructus only has three complete cervicals, and I’ve yet to see anything demonstrating hochuanensis or sinocanadorum are closer to it than to Xinjiangtitan.

  6. Matt Wedel Says:

    Oh, man, there’s a big discussion of that very problem in the Moore et al. (2020) osteology of Klamelisaurus, which is also of interest because they recover Euhelopus with the mamenchisaurs in quite a few trees.

  7. OK, I mean M. hochuanensis—the dinosaur whose holotype is responsible for the line in every kid’s book that Mamenchisaurus is the longest-necked dinosaur. M. sinocanadorum, from what’s preserved, appears to have neck proportions closer to Xinjiangtitan and Omeisaurus than the shorter-necked M. hochuanensis and M. youngi.

    I have my guesses about where M. constructus falls relative to the other species, and I agree there’s nothing solid linking it to any of the referred species to the exclusion of Chuanjiesaurus, Qijianglong, and Xinjiangtitan. I recall hearing somewhere recently that the holotype of M. constructus might be lost, which would certainly complicate matters.

  8. LeeB. Says:

    And Omeisaurus species are all over the place too.
    And the most recently named species (2020) is not compared with the type species of that “genus”.

  9. For sure, Omeisaurus is a mess too—and as is apparently the case with M. constructus, the holotype of O. junghsiensis appears to be lost, unfortunately. O. maoianus seems like the worst offender; it appears to be more similar to the various species of Mamenchisaurus than to any other species of Omeisaurus, and is recovered in phylogenetic analyses accordingly.

  10. Andrew Stuck Says:

    Maybe you’re a little late in the sense that this study is a couple years old, but it’s timely nonetheless. There’s been a mild flurry of interest in the BYU Barosaurus on Twitter in the past week.

  11. Mickey Mortimer Says:

    How do you lose sauropod skeletons?!

  12. Mike Taylor Says:

    @Mickey, it does seem that quite a few Chinese holotypes have wandered off somehow. It’s a common theme I hear from Western researchers returning from trips to China.

    @Andrew, thanks for the tip, I did a search and enjoyed seeing that the idea is properly out there by this stage. Matt and I really, really need to write this up.

  13. Matt Wedel Says:

    When I went to the IVPP in 2004, I had a list of about 20 things I wanted to see. Of that list, they were able to find one. So I entertained myself looking at other stuff.

  14. Mickey Mortimer Says:

    @Mike, sure a lot gets lost at the IVPP but unless it’s a single small block like the Jibeinia type, usually the whole thing doesn’t go missing (e.g. the stegosaurs discussed by Madment and Wei 2006 generally had elements remaining). So an entire sauropod skeleton surprises me.

    @Matt, do you happen to recall what the 19 missing specimens were? It’s good to have these on record…

  15. Dong et al. 1983 say that the majority of the holotype of O. junghsiensis was lost in transport during World War II—so I guess that’s how you lose a sauropod! They apparently designated a neotype as well, although it doesn’t seem they met the requirements for neotype designation laid out in ICZN article 75. Which might be for the best, given the potential for verschlimmbesserung.

    I don’t know what happened to the holotype of M. constructus, nor do I remember where I read it was lost. It’s possible I don’t remember correctly. Another lost Chinese sauropod is Gongxianosaurus—the holotype was apparently destroyed when the building it was stored in collapsed.

    Dong, Zhou & Yang (1983) Dinosaurs from the Jurassic of Sichuan. Palaeontologica Sinica 162 (23): 1-136.

  16. […] be in the top 7 longest cervical vertebrae on the planet (see the latest version of the list in this post), narrowly beating out the 118-cm cervical of Puertasaurus. In fairness, the preserved cervical of […]

  17. Tom Says:

    What about Futalognkosaurus dukei? Neck 10.6 meters long….or not?

  18. Matt Wedel Says:

    Mickey, I’m sorry, I don’t know. It’s possible that list resides in one of my research notebooks from grad school, and if I happen to find it I will let you know.

    Tom, re: the neck of Futalognkosaurus–are there published measurements? Given how big that animal is, 10.6 meters sounds plausible, I’m just curious about the source.

  19. Matt Wedel Says:

    Right. As I explained in that post, the scale bars aren’t accurate. AFAIK, no new data–as in actual measurements of the cervicals–have been published since, although I’d love to be proven wrong on that point. So I know about as much now as I did back then.

    I guess my answer to your “is it relevant?” question is that it’s interesting, in that knowing the neck length of any big sauropod is interesting, but it’s not ground-breaking or particularly noteworthy in a discussion of longest necks, even among titanosaurians. There are already basal somphospondyls, like Sauroposeidon, and derived titanosaurs, like Patagotitan, that had necks longer than that of Futalognkosaurus. So if the neck of Futalognkosaurus was 10.6 meters, great, that’s a nice thing to know about that genus, but it doesn’t push the envelope for titanosaurians or somphospondyls. It also doesn’t get a look in on the list of longest cervicals, since none of the scaled images suggest that any of the cervicals were longer than a meter, and the bar to even get into the top 7 is 118cm.

    Where Futalognkosaurus probably wins is longest complete neck among macronarians–AFAIK all of the larger taxa have incomplete necks. It might even be the second-longest complete neck of anything, ever, after Xinjiangtitan. Is that what you were getting at? If so, I’m sorry to have been so obtuse!

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