| Yunganglong | |
|---|---|
 | |
| Skull elements | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Dinosauria |
| Clade: | †Ornithischia |
| Clade: | †Ornithopoda |
| Clade: | †Hadrosauromorpha |
| Genus: | †Yunganglong Wanget al.,2013 |
| Type species | |
| †Yunganglong datongensis Wanget al., 2013 | |
Yunganglong is anextinctgenus ofbasalhadrosauroiddinosaur known from the earlyLate Cretaceous lowerZhumapu Formation ofZuoyun County,Shanxi Province of northeasternChina. It contains a single species,Yunganglong datongensis.[1]
Yunganglong was first described and named by Run-Fu Wang, Hai-Lu You, Shi-Chao Xu, Suo-Zhu Wang, Jian Yi, Li-Juan Xie, Lei Jia and Ya-Xian Li in2013 and thetype species isY. datongensis. Thegeneric name honorsYungang Grottoes, aUNESCO World Heritage site built in the 5th and 6th centuries about 50 km east of the fossil locality, and derived fromlong meaning "dragon" inChinese. Thespecific name refers to the city ofDatong, located in northernShanxi province, where the holotype was found.[1]
Yunganglong is known solely from theholotype SXMG V 00001, field number ZY007, an associated but disarticulated partialskeleton housed at theShanxi Museum of Geology. The holotype came from a single individual, and includes the caudodorsal part of the skull, ZY007-37 and ZY007-38, separated along the floor of thebraincase; twocervical vertebrae ZY007-40 and ZY007-41; partial dorsal neural arch and neural processes ZY007-36; twocaudal vertebrae, including the proximal ZY007-27 and the middle ZY007-19; distal portions of bothischia (left ZY007-11 and right ZY007-12, distal end of leftfemur ZY007-32, proximal portion of righttibia ZY007-1, and distal portion of left tibia with astragalus ZY007-2. The remains were collected in 2011 from Locality 7 of theZhumapu Formation, as a part of a project to find dinosaurs for the Shanxi Museum of Geology, initiated by the Department of Land and Resources of Shanxi Province. SXMG V 00001 was found in the vicinity ofZuoyun County, from the lower part of Zhumapu Formation, dating to the earlyLate Cretaceous based onbiostratigraphic correlations, overlying the lateEarly CretaceousZuoyun Formation. Other than SXMG V 00001,ankylosaur andceratopsian remains were found from the newly discovered localities. The first dinosaur record in Shanxi Province was reported by Young (1958), from two localities in Zuoyun County. He assigned hadrosauroid material recovered from the Xinyaogou locality of the Zuoyun area toBactrosaurus johnsoni, including two isolated teeth, some vertebrae including a series of 25 caudal vertebrae, onerib, one righthumerus and several manual and pedal bones. Although no overlapping material exists, based on the more basal phylogenetic position and lower stratigraphic horizon ofYunganglong compared toBactrosaurus, Young's material more probably pertains toYunganglong.[1]
Wanget al. (2013) diagnosedYunganglong datongensis using a unique combination of four characters. The caudal surface of the supraoccipital inYunganglong and more advanced hadrosauroids is inclined steeply forward at approximately 45°, while nearly vertical inJintasaurus and less derived Hadrosauriformes. The horizontal portion of the paroccipital process is caudolaterally extended and accompanied by thesquamosal, but laterally extended inJintasaurus and less derived Hadrosauriformes. As observed inYunganglong andJintasaurus, but not inBactrosaurus and more advanced taxa, the pendent portion of the paroccipital process does not curve cranially. Finally,Yunganglong and less derived Hadrosauriformes possess a deep, U-shaped, intercondylar extensor groove on thefemur, partially enclosed by expansion of medial and lateralcondyles, while in more advanced taxa (e.g.Nanyangosaurus) it is fully enclosed.[1]
Yunganglong cannot be directly compared with three other non-hadrosaurid hadrosauroids. These includeShuangmiaosaurus from the early Late Cretaceous ofLiaoning Province of northeastern China, and two other early Late Cretaceous taxa from North America: theCenomanianProtohadros and theTuronianJeyawati. Like other hadrosauroids,Yunganglong was a ground-dwellingherbivore that could walkbipedally, and could stand on all four legs. The skull ofYunganglong is relatively wide and low.[1]
Based on itsmorphology Wang et al. (2013) showed thatYunganglong was more derived than the basal hadrosauriformIguanodon but more primitive than thehadrosaurids, such as the well knownEdmontosaurus andCorythosaurus. To further explore thephylogenetic position ofY. datongensis amonghadrosauriforms, Wanget al. (2013) used a modified version of the data matrix first presented by Sues and Averianov (2009).Nanyangosaurus,Shuangmiaosaurus, andYunganglong were added to the matrix, and two character codings were modified. In the strict consensus tree,Yunganglong was recovered as more advanced thanProbactrosaurus, in an unresolvedpolytomy withJintasaurus,Protohadros,Nanyangosaurus,Shuangmiaosaurus,Levnesovia,Bactrosaurus,Tanius,Telmatosaurus and the clade formed byAralosaurus andHadrosauridae. The 50% majority rule tree resolved its phylogenetic position further, as shown in thecladogram below.[1]
