| Tambatitanis | |
|---|---|
 | |
| Caudal vertebrae ofTambatitanis | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | †Sauropodomorpha |
| Clade: | †Sauropoda |
| Clade: | †Macronaria |
| Clade: | †Titanosauria |
| Genus: | †Tambatitanis Saegusa & Ikeda,2014 |
| Type species | |
| †Tambatitanis amicitiae Saegusa & Ikeda, 2014 | |
Tambatitanis (meaning "Tamba giant", after Tamba, the name given to the northwest of Kansai, Japan[1]) is an extinctgenus oftitanosauriform, possibly atitanosaurian,sauropoddinosaur from theEarly Cretaceous (earlyAlbian) agedOhyamashimo Formation of theSasayama Group. It is known from a singlespecies,Tambatitanis amicitiae, known from a partial skeleton.[1]
The holotype specimen of theTambaitanis, MNHAH D-1029280 was initially discovered in August 2006, by Shigeru Murakami and Kiyoshi Adachi in the reddish mudstone bed of theOhyamashimo Formation (Lower Formation of the Sasayama Group) on a riverbed of the Sasayama RIver in Kamitaki, Sannan-Cho,Tamba-Sasayama city, ofHyōgo Prefecture, Japan.[2] It took five field seasons, from 2006 to 2010 to excavate a fossil because access to the skeleton was only available during the winter when the water level of the river becomes lowest. It was originally called 'Tamba-Ryu' before the publication in 2014. The specimen is somewhat semi-articulated and includes teeth, a braincase, a dentary, an atlas, a fragmental cervical vertebra, dorsal ribs, two fragmental dorsal vertebrae, a pubis, an ilium, sacral spines, presumable first sacral ribs, 22 caudal vertebrae, and 17 chevrons.[1]
In 2014, Haruo Saegusa and Tadahiro IkedadescribedTambatitanis amicitiae as a new genus and species of titanosauriform sauropod based on these remains. Thegeneric nameTambatitanis is derived from the words,Tamba, the city where the fossil was discovered, with theAncient Greek word "titanis", meaning titan. Thespecific name,amicitiae was derived from theLatin word "amicitia", referring to the friendship between 2 discoverers of this fossil.[1]
Phylogenetic analysis from Saegusa and Ikeda (2014) suggestsTambatitanis was Euhelopodidae, but its specific placement is uncertain among this group due to polytomy shown in the matrix, which is mainly based on D'Emic (2012).[3] In contrast, the describers ofRuixinia recovered this taxon withinTitanosauria based on their phylogenetic analysis in 2023, the cladogram of which can be seen below:[4]
Tambatitanis is known from the Ohyamashimo Formation (Sasayama Group), which dates to the early–middleAlbian age from the end of theEarly Cretaceous.[5] These layers are predominantly made up bysandstones,mudstones, andconglomerates. Thedepositional environment represents afluvial system with asubhumid tosemi-arid climate.[6] Dinosaur teeth are common in various localities throughout this formation including those belonging to other theropods (dromaeosaurids,therizinosaurs, andtyrannosauroids) as well assauropods,ankylosaurs, andiguanodontians.[7] Several dinosaurianoospecies (egg fossils) have also described, includingHimeoolithus,Subtiliolithus,Nipponoolithus, andPrismatoolithus.[8] Themonstersaurian lizardMorohasaurus and thetroodontid theropodHypnovenator[5] are known from the formation.[9] Fossils of an unnamedneoceratopsian, including several skull bones, are also known from the formation.[10] Although not specified as this Formation in original descriptions, Sasayama Group have some other fossil fauna known, such aseutherianSasayamamylos,[11]scincomorphPachygenys,[12] two frogsHyogobatrachus andTambabatrachus.[13]
