Qilong’s Tutorial

Hexinlusaurus multidens is the name given to a skeleton of a not-quite fully mature animal from the famous Dashanpu dinosaur quarry in Zigong City, in the Ziliujing District of Sichuan Province, China. The animal was originally given the name Yandusaurus multidens (He & Cai, 1983) but later transferred to Agilisaurus as Agilisaurus multidens because it was determined to be “not that similar” (Peng, 1992). Later, the same treatment was given in regard to Agilisaurus, and it was transferred to a new name, Hexinlusaurus, to honor one of the species’ original descriptors, Dr. He Xin-lu (Barrett et al., 2005).


The name will eventually be changed, but this really is Hexinlusaurus multidens, I swear!

This is the animal that forms the basis of my moniker (via some confusion) and I really need to get the skeleton redone. It is remarkable to me how “modern” it still looks in regards to the various revisions others of my skeletons have gone through, and I find I will not modify it by much. I have lost the original digital file, so in preparing the integument version of this skeleton for PhyloPic, I had to deal with a relatively low-quality image, but the result is largely the same, and it didn’t come out too bad.

Bizarrely, I’ve added a lot of soft tissue around the neck on this animal, which isn’t comprised of filaments or “dinofuzz,” but rather of extra tissues or subdermal ligaments of the like suggested to comprise the “humps” seen in some of Greg Paul’s more recent hadrosaurid skeletons (some of which are available for viewing at his website, here). Such a “hump” seems elegant in the least, largely due to the ornithopod ventroflexion of the anterior dorsal vertebrae (where the vertebrae  as a series begin to sharply turn downward), a feature that seems to resist even opisthotonic distortion in preserved skeletons. It is quite likely, rather, that as in mammals and birds with highly flexed posterior necks, rising sharply from the dorsal series (Taylor et al., 2009), deep and superficial ligaments forming the natural architecture of the next would cross nearly the entire gap between anterior dorsals and anterior neck, and thus essentially “shorten” the neck by half. I’ve not made this assumption here as the neck anatomy of basal ornithopods such as Hexinlusaurus multidens has yet to be investigated.

Note that two modifications to the skeleton at top have been made in the spread below it, the first being the removal of the fleshy, nonmuscular “cheek”. This is done due to the complete lack of positive data regarding the presence of such a structure in any non-mammalian, non-psittaciform animal (yes, I have to consider that parrots, like mammals, actually have a fleshy, muscular “cheek,” although it’s not homologous, the muscles involved are unique to parrots). The second is that I tended in my art, when I drew the skeleton, to omit large sections of unknown material from the black outline, so that the tail is missing. Here, I have reconstructed the tail to be about 50% of the animal’s total length. It may have been quite a bit longer. The skeleton is also not modified in the original from its original “Paulian” design, and does not correspond to my modern “kicking off” posture as demonstrated here. hopefully, at some point, I will get around ti redoing these, but they do take time and I will attempt them in finer detail. I am still finishing my MPC-D 100/42 skeleton, mentioned here.

Barrett, P. M., Butler, R. J. & Knoll, F. 2005. Small-bodied ornithischian dinosaurs from the Middle Jurassic of Sichuan, China. Journal of Vertebrate Paleontology 25(4):823-834.
He X.-l. & Cai K.-j. 1983. [A new species of Yandusaurus (hypsilophodont dinosaur) from the Middle Jurassic of Dashanpu, Zigong, Sichuan.] Journal of Chengdu College of Geology, Supplement 1:5-14. [in Chinese]
Peng G-z.. 1992. [Jurassic ornithopod Agilisaurus louderbacki (Ornithopoda: Fabrosauridae) from Zigong, Sichuan, China]. Vertebrata PalAsiatica 30:39-51. [in Chinese]
Taylor, M. P., Wedel, M. J. & Naish, D. 2009. Head and neck posture in sauropod dinosaurs inferred from extant animals. Acta Palaeontologica Polonica 54(2):213-220.

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3 Responses to Qilong’s Tutorial

  1. “This is done due to the complete lack of positive data regarding the presence of such a structure in any non-mammalian, non-psittaciform animal”

    *cough* Ankylosaur cheek osteoderms *cough*

    Seems odd to not include cheeks, for which we have good evidence in some ornithischians and circumstantial evidence in others, but to include a hump “of extra tissues or subdermal ligaments” which I don’t believe we have evidence for in any dinosaur. Cheeks seem at least as well supported as the midline scales you gave it, since the latter are only known in hadrosaurs but not ceraopsians, and Hexinlusaurus is a basal cerapod.

    • Eventually, I would get to that, save that the underlying tissue relationships are (as yet) unknown, especially if you have to consider how the muscular underlying tissues have to expand with a giant bone embedded in the tissue. One might consider that the osteoderm is attached to merely to the mandible, without ever having to invoke putting a stretch of tissue betwene upper and lower without ANY sort of precedent analogue to back up THAT assumption. ARE there any living animals with osteoderms covering their cheeks to presume the argument for the two or three skulls in ankylosaurs is actually apt?

  2. Pingback: Skin Deep | The Bite Stuff

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