| Ruixinia | |
|---|---|
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | †Sauropodomorpha |
| Clade: | †Sauropoda |
| Clade: | †Macronaria |
| Clade: | †Somphospondyli |
| Genus: | †Ruixinia Mo et al.,2022 |
| Species: | †R. zhangi |
| Binomial name | |
| †Ruixinia zhangi Mo et al., 2022 | |
Ruixinia is anextinct genus ofsomphospondylantitanosauriform dinosaur from theEarly Cretaceous (Barremian)Yixian Formation ofChina. The genus contains asingle species,Ruixinia zhangi. TheRuixinia holotype is a partial articulated skeleton with the most complete series of caudal vertebrae known from any Asian titanosauriform.[1]
TheRuixiniaholotype specimen, ELDM EL-J009, was found in sediments of theYixian Formation inBeipiao,Liaoning Province, northeasternChina. This locality is dated to theBarremian age of theEarly Cretaceous period. The fossil material consists of a partial articulated skeleton includingcervical,dorsal, andsacral vertebrae,caudal vertebrae and associatedchevrons, dorsalribs, and a leftilium,pubis,femur,tibia,astragalus,metatarsal V, and possible pedalphalanx. At the time of its description, the fossil material was still partially embedded inmatrix, with only the left side of the bones prepared.[1]
In 2022,Ruixinia zhangi wasdescribed as a new genus and species of titanosauriform dinosaurs by Jinyou Mo, Feimin Ma, Yilun Yu, andXing Xu. Thebinomial honorsRuixin Zhang, a contributor to theErlianhaote Dinosaur Museum.[1]
Ruixinia was a mid-sized sauropod, with an estimated length of approximately 12 meters.[1]
The neck ofRuixinia was over 4 meters long and consisted of at least 15 cervical vertebrae. Such a high number of cervical vertebrae is similar toDongbeititan,Euhelopus, andMamenchisaurus.[1]
The tail ofRuixinia contained at least 52 vertebrae. The last few vertebrae were fused together, an unusual trait in sauropods otherwise only known to occur in some Jurassic Asian sauropods such asShunosaurus andMamenchisaurus. However, the structure of the fused vertebrae differs between the three taxa. InRuixinia, the fused vertebrae form a rodlike structure.[1]
The chevrons are distinctive, particularly that of the 20th caudal vertebra, which has a pentagonal shape.[1]
Mo et al. (2022) recoveredRuixinia to be a basaltitanosaur, placed as thesister taxon to a clade containingDaxiatitan andXianshanosaurus.[1] However, bothDaxiatitan andXianshanosaurus have also been suggested to have affinities with mamenchisaurids,[2] and Mo et al. noted several similarities betweenRuixinia andMamenchisaurus.Ruixinia was not found to be closely related to either of its contemporaries,Dongbeititan orLiaoningotitan. Thecladogram below displays the results of thephylogenetic analyses of Mo et al. (2022).[1]
In their 2024 description of the basal titanosaurGandititan, Han et al. includedRuixinia in their phylogenetic analyses, recovering it as a member of theEuhelopodidae, rather than the Titanosauria, as the sister taxon toJiangshanosaurus. The results of their phylogenetic analyses are shown in the cladogram below:[3]
Ruixinia is a member of theJehol Biota. Two other sauropod genera,Dongbeititan andLiaoningotitan, are also known from the Jehol Biota.[1]
