Klamelisaurus (meaning "Kelameili Mountains lizard") is a genus of herbivorous sauropod dinosaur from the Middle Jurassic Shishugou Formation of China. The type species is Klamelisaurus gobiensis, which was named by Zhao Xijin in 1993, based on a partial skeleton discovered in 1982 near the abandoned town of Jiangjunmiao. Zhao described Klamelisaurus as the only member of a new subfamily, Klamelisaurinae, among the now-defunct primitive sauropod order Bothrosauropodoidea. Since Zhao's description, Klamelisaurus received limited attention from researchers until Andrew Moore and colleagues redescribed it in 2020.
A relatively large sauropod measuring approximately long, with half of the length being its neck, Klamelisaurus can be distinguished from its relatives by characteristics of the and . Phylogenetic analyses have suggested that Klamelisaurus belonged to the Mamenchisauridae, a group of Middle to Late Jurassic and primarily Chinese sauropods, although its close relatives also include a mamenchisaurid from Thailand. While paleontologist Gregory S. Paul suggested that Bellusaurus, known only from juvenile specimens, was a juvenile Klamelisaurus, this proposal has been rejected based on anatomical evidence, and the fact that Bellusaurus was geologically younger.
Discovery and naming
Between 1981 and 1985, a field crew from the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) conducted excavations in the Junggar Basin of the Xinjiang Autonomous Region of China, as part of a research project titled "Evolution of the Junggar Basin and the Formation of Petroleum". The work was conducted in cooperation with the Chinese Academy of Sciences and the Xinjiang Office of Petroleum. In 1982, these excavations uncovered the skeleton of a sauropod dinosaur north of the now-abandoned town of Jiangjunmiao, located in the eastern Junggar Basin. The skeleton was excavated and collected in 1984 by the IVPP field team.
The specimen, which was catalogued under the specimen number IVPP V9492, consists of teeth, most of the vertebral column (save for the first seven (neck vertebrae) and the end of the tail), , the right shoulder girdle and arm (, , , , , and ), and the right hip girdle and leg (, , , , , and ). At the time of its discovery, the specimen was already weathered. After it was transported to Beijing, with preparation and restoration work beginning in 1985, it deteriorated further due to fluctuations in temperature and humidity. Nearly all of the bones underwent reconstruction and painting, and many of them were encased in a metal armature for display. The referral of the fragmentary teeth to the specimen was unexplained, and they can no longer be located along with two ribs, two of the wrist, a of the ankle, and some bones of the tail. They also located several (from the underside of the tail), the bottom end of the left femur, and parts of the left hand that were not mentioned by Zhao.
In 1993, Xijing Zhao described IVPP V9492 as the type specimen of a new genus and species, Klamelisaurus gobiensis. Due to the condition of the specimen, he only conducted a "simple description". The generic name Klamelisaurus refers to the Kelameili Mountains to the north of Jiangjunmiao, of which "Klameli" is a variant spelling. The specific name gobiensis refers to the Gobi Desert, in which Jiangjunmiao is located. Following Zhao's description, IVPP V9492 received limited attention in the literature until it was redescribed by Andrew Moore and colleagues in 2020. They noted that the specimen's reconstruction had been altered since Zhao's description, namely by the addition of a frontward-projecting process on the 15th and the removal of a fabricated connection to the (vertebral body).
Description
Klamelisaurus was described as a "relatively large" sauropod by Zhao in 1993. In 2016, American paleontologist Gregory S. Paul estimated its length at in length and in weight, albeit based on the hypothesis that Klamelisaurus represented the adult form of Bellusaurus. In 2020, Moore and colleagues listed a number of characteristics (following a 2013 study by Michael Taylor and Mathew Wedel) which identified the type specimen as an adult: the lack of unfused sutures in the vertebral centra; the fusion of the (hip vertebrae), the fusion of the cervical ribs to their corresponding centra; and the fusion of the scapula and coracoid in the shoulder.
Vertebrae Zhao stated that the type specimen of Klamelisaurus preserved nine cervicals (neck vertebrae), out of an estimated total of sixteen with a total length of . Moore and colleagues concurred with the number of cervicals, but they noted that the tenth preserved vertebra shows characteristics of both cervicals and (back vertebrae). They estimated a total of fifteen to seventeen cervicals, based on other sauropods with similar patterns of vertebral variation, and indicated that Klamelisaurus had a shorter neck than Omeisaurus tianfuensis, Mamenchisaurus hochuanensis, and M. sinocanadorum. Zhao's original diagnosis or list of distinguishing characteristics (which have been reassessed as being widespread among sauropods) noted that the cervicals were (with centra convex in front and concave behind); had centra 1.5 to 2 times the length of the dorsal centra; and had tall , which were bifid (two-pronged) at the back of the neck. Moore and colleagues noted two unique features (autapomorphies) in the cervicals. First, the spinoprezygapophyseal (SPRLs), ridges of bone extending forward from the neural spines, bore irregular, plate-like extensions. Second, below the SPRLs and in front of depressions called the spinodiapophyseal (SDFs), the sides of the centra bore a set of deep (openings). Although these foramina were present only on the right side of the centra, Moore and colleagues considered them to be unique due to their consistency and the presence of similar structures in other sauropods.
A number of sauropods possess laminae or struts that cross the SDFs in their cervical vertebrae, linking the projecting from the back of the vertebrae to the extending from the front of the vertebrae. These include Euhelopus (where it is a distinguishing characteristic) and Nigersaurus; this structure has been named the "epipophyseal-prezygapophyseal lamina" (EPRL). Moore and colleagues considered two structures in Klamelisaurus to potentially correspond to the EPRL: extensions of the epipophyses that invade the SDFs from the rear, and isolated struts in the middle of the SDFs. Similar structures in Uberabatitan had previously been considered as evidence of a "segmented EPRL". However, for Klamelisaurus, Moore and colleagues interpreted the former to be an attachment for the intercristal muscles of the neck, based on the surface texture and comparisons with ostriches, while they considered the latter to be a pneumatic structure created by . Thus, they argued that previous literature had conflated distinct and diverse muscular and pneumatic structures as components of the EPRL.
Moore and colleagues identified twelve dorsals and six sacrals in the type specimen of Klamelisaurus. (Zhao previously identified the first sacral of Moore and colleagues as the last dorsal, giving thirteen dorsals and five sacrals.) Although sacral vertebrae are usually identified by contact with the ilium, these bones are not in association in the type specimen. Instead, Moore and colleagues noted a bridge of bone connecting the and (processes on the side of the vertebra), which was either fused to the lost sacral rib (as in other sauropods) or was not associated with a rib at all. Zhao's diagnosis noted that the dorsals were opisthocoelous; the dorsals had shallow (neurovascular openings) and simple lamination (ridging); the dorsal neural spines were low, with the first few being bifid and the last few having expanded tips; the sacral centra were fused such that their boundaries were not visible; and the first four sacral neural spines were fused. Moore and colleagues identified two unique features in the dorsals. First, the sides of some of the dorsals bore sets of three posterior centroparapophyseal laminae (PCPLs). Second, the spinodiapophyseal laminae (SPDLs) on the sides of the neural spines were bifurcated in the middle and rear dorsals, but unlike Bellusaurus the two prongs did not reach the SPRLs or the SPOLs (spinopostzygapophyseal laminae, the rear counterparts of the SPRLs).
Parts of nineteen (tail vertebrae) were found by Moore and colleagues: parts of the first four caudals (labelled as caudals 1–4), five more neural spines from the front of the tail (labelled as caudals 6 and 8–11), and eleven centra from the middle of the tail (labelled as caudals 18–27 and 33). Zhao originally counted two complete caudals, ten neural spines from the front, and ten middle centra, based on which he estimated that sixty were originally present with a total length of . Zhao's list of characteristics indicated that the first few caudals were (with centra concave in front and convex behind), with the rest being (with centra concave on both ends); and the caudal neural spines were claviform (thicker at the tip) and slanted extremely to the rear. Characteristics of the caudals that differentiate Klamelisaurus from Tienshanosaurus include the procoelous front caudals, and the front edge of the tip of the neural spines being slanted to the point of reaching behind the rear edge of the processes known as .
Limbs and limb girdles In terms of limb proportions, Zhao indicated that the forelimb of Klamelisaurus was three-quarters the length of the hindlimb, and the ulna and tibia were respectively two-thirds the lengths of the humerus and femur. He considered these proportions to be distinguishing characteristics of Klamelisaurus.
According to Zhao, Klamelisaurus had a thin, elongated scapula and a slender, small coracoid (the former being 4.3 to 4.5 times the length of the latter), but Moore and colleagues did not consider his measurements of the scapula to be reliable as most of the bone was covered by plaster and paint. The , located at the outer bottom end of the scapula, was broader than in Cetiosaurus, Shunosaurus, and many early-diverging sauropodomorphs, and the top edge of the acromion was straight, not concave like Tienshanosaurus. Zhao observed that the top of the humerus was thick, and slightly curved. Unlike Bellusaurus and many neosauropods, the head of the humerus did not have an overhanging sub-circular process. Moore and colleagues noted a unique characteristic of the humerus: the front surface of the top inner end bore a depression, which was bordered by an S-shaped shelf ending in a rounded bump. Zhao n that the ulna was longer than the relatively straight radius, and he suggested that the degree of expansion of the upper ulna was unique; Moore and colleagues instead found that it was comparable to many other sauropods. Also unlike Bellusaurus, the anteromedial process at the top of the ulna had a convex (not flat) surface that sloped below the . The bottom of the front of the radius bore a depression, which Haestasaurus also had, but was otherwise uncommon among sauropods.