| Ruyangosaurus | |
|---|---|
 | |
| Skeleton | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | †Sauropodomorpha |
| Clade: | †Sauropoda |
| Clade: | †Macronaria |
| Clade: | †Titanosauria |
| Genus: | †Ruyangosaurus Luet al.,2009 |
| Type species | |
| †Ruyangosaurus giganteus Lüet al.,2009 | |
Ruyangosaurus (Ruyang County lizard) is agenus oftitanosauriformsauropoddinosaur recovered from theEarly CretaceousHaoling Formation of China. Thetype species isR. giganteus, described in2009 byLü Junchanget al.[1]
Along withHuanghetitan andDaxiatitan,Ruyangosaurus is among the largest dinosaurs discovered inCretaceous Asia. In 2016Gregory S. Paul gave a length of 30 meters (98 ft) and a weight of 50+ tonnes (55 short tons) - making it a 'mega-sauropod'.[2]
According to another estimate,Ruyangosaurus was probably about 35 meters (115 ft) long, as evidenced by its 207 cm long femur and 127 cm long right tibia.[3] In 2020 Molina-Perez and Larramendi gave a lower estimation of 24.8 meters (81.4 ft) and 34 tonnes (37.5 short tons).[4]
The describers ofRuyangosaurus assigned it toAndesauridae.[1] However, Andesauridae is not monophyletic and, as such, is no longer used.[5]
Comprehensive phylogenetic analyses of Titanosauriformes conducted by Philip Mannion and colleagues in 2013 foundRuyangosaurus to be in a polytomy withAndesaurus and other basal titanosaurs and near-titanosaur somphospondyls, supporting the original description's assertion of phylogenetic proximity of it andAndesaurus, though not the precise taxonomic assignment, with further modifications of the dataset resolving similar conclusions.[6][7][8] However, not all phylogenetic analyses have supported its position as a somphospondyl. A phylogenetic dataset following the description of additional material forRuyangosaurus to be a non-titanosauriform macronarian, closely related toYunmenglong.[9]
The phylogenetic analysis of Mannionet al. in 2019 incorporated these updated discoveries into their earlier analysis, along with additional new knowledge for other mid-Cretaceous Asian taxa considered close to Titanosauria. They foundRuyangosaurus to either be close toAndesaurus as a basal titanosaur when all characters were considered equally important, or in a large clade of early titanosaurs potentially given the nameEuhelopodidae related to taxa likeYongjinglong andHuanghetitan ruyangensis. Two trees of the results are shown below, equal weighting displaying the results of basal titanosauria, and relationships within Euhelopodidae of extended-implied weighting with a mild down-weighting of highly variable characters (k=9).[10]
Ruyangosaurus shared its habitat withXianshanosaurus,"Huanghetitan" ruyangensis,Yunmenglong,Luoyanggia, andZhongyuansaurus. The horizon ofRuyangosaurus was originally described as being of "earlyLate Cretaceous" age,[1] but recent work has assigned it an Aptian-Albian Age based on fieldwork and analysis of invertebrate and microfossil assemblages.[11]
