| Tanius | |
|---|---|
 | |
| Restoration ofT. sinensis | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Dinosauria |
| Clade: | †Ornithischia |
| Clade: | †Ornithopoda |
| Clade: | †Hadrosauromorpha |
| Genus: | †Tanius Wiman,1929 |
| Species[1] | |
| |
Tanius (meaning "of Tan") is agenus ofhadrosauroiddinosaur. It lived in the LateCretaceous ofChina. Thetype species, named and described in 1929 byCarl Wiman, isTanius sinensis. The generic name honours the Chinese paleontologistTan Xichou ("H.C. Tan"). Thespecific epithet refers to China.[2] In 2010Gregory S. Paul estimated the length ofTanius at 7 metres (23 ft) and its weight at 2 metric tons (2.2 short tons).[3]
In April 1923, H. C. T'an discovered the remains in the east ofShandong at the village of Ch'ing-kang-kou, ten kilometres southeast ofLai Yang. In October of the same year they were excavated by Tan's associate, the Austrian paleontologistOtto Zdansky. Although the specimen was originally rather complete, only parts could be salvaged. Theholotype,PMU R.240, was recovered from theJiangjunding Formation of theWangshi Series dating from theCampanian. It consists of the back of the skull, which was flat and elongated.
Other species originally assigned toTanius have been moved to other genera. These include:Tanius prynadai named in 1939 byAnatoly Nikolaevich Ryabinin,[4] which was assigned toBactrosaurus; andTanius chingkankouensis named in 1958 byYang Zhongjian,[5] andTanius laiyangensis named in 1976 byZhen Shuonan,[6] which were both later consideredjunior subjective synonyms ofTsintaosaurus.[7] However, a more recent study, Zhanget al. (2017) determined thatT. sinensis andT. chingkankouensis were valid species ofTanius, and thatT. laiyangensis was probably not valid.[1] Zhang et al. (2019) re-assessed"Tanius" laiyangensis as a member of the saurolophine clade Kritosaurini, the first of the clade from Asia.[8]
The type speciesTanius sinensis was found in theJiangjunding Formation of the ChineseWangshi Group.[1] The Jiangjunding formation consists purpley-grey or reddy-brown sandstones or various consistencies, siltstones and conglomerates. The Wangshi group ofgeologic formations is generally considered to be from theLate Cretaceous, although some regions are older. Based on the discovery ofPinacosaurus, only known elsewhere in theDjadokhta Formation or regions of the same age, the Wangshi Group was presumed to be a similar age of 75-71 million years old. The specific age for theHongtuya Formation has been identified as 73.5-72.9 mya. As the Hongtuya is directly older than the Jiangjunding, it was identified thatTanius sinensis lived in the latestCampanian to earliestMaastrichtian by Borinder in 2015.[9]
The Jiangjunding Formation was deposited in a fluvial to lacustrine environment. The climate was warm and humid during the majority of the timespan, although it was beginning to dry out after the Jiangjunding. Taxa that lived alongsideTanius in the formation include theankylosaurPinacosaurus cf. grangeri; possibly thecerapodanMicropachycephalosaurus; intermediatesauropods; intermediatecoelurosaurs; and intermediatecheloniids which show similarities toNanhsiungchelyidae. Multiple localities of dinosaur eggs have also been identified.[9]
BothT. chingkankouensis andT. laiyangensis were discovered in theJingangkou Formation, which is directly above the Jiangjunding. This formation has been the site of massive excavations of hadrosaurs in both the 1950s and the 2010s. A majority of the strata is green-grey mudstone, where the bones excavated are coloured black. The sediment in the location of the hadrosaur excavations was deposited by a mudflow event, where the carcasses were trapped and moved a short distance before rapid burial. At least 20 individuals of hadrosaurs have been uncovered, of various ages. Hadrosaurs from these localities includeTanius,Tsintaosaurus,Laiyangosaurus andShantungosaurus. Other taxa uncovered include thetheropodsChingkankousaurus andcf. Szechuanosaurus campi, and thetestudineGlyptops.[1]
