''Jiangxititan'' is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

genus of

somphospondylan Somphospondyli is an extinct clade of titanosauriform sauropods that lived from the Late Jurassic until the end of the Late Cretaceous, comprising all titanosauriforms more closely related to Titanosauria proper than Brachiosauridae. The remain ...

titanosauriform Macronaria is a clade of sauropod dinosaurs. Macronarians are named after the large diameter of the nasal opening of their skull, known as the external naris, which exceeded the size of the orbit, the skull opening where the eye is located (hence ...

dinosaur from the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''cre ...

Nanxiong Formation The Nanxiong Formation (also known as Yuanpu Formation) is a Late Cretaceous geologic Formation (geology), formation in Guangdong Province. Dinosaur remains are among the fossils that have been recovered from the formation. Description It cons ...

of China. The genus contains a single species, ''J. ganzhouensis'', known from several articulated vertebrae with ribs. Originally described as a titanosaur, ''Jiangxititan'' was later suggested to be a non-titanosaurian somphospondylan.

Discovery and naming

The ''Jiangxititan''

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

specimen, NHMG 034062, was discovered in sediments of the

near Tankou Town in

Ganzhou Ganzhou (), alternately romanized as Kanchow, is a prefecture-level city in the south of Jiangxi province, China, bordering Fujian to the east, Guangdong to the south, and Hunan to the west. Its administrative seat is at Zhanggong District. His ...

City of

Jiangxi Province ; Gan: ) , translit_lang1_type2 = , translit_lang1_info2 = , translit_lang1_type3 = , translit_lang1_info3 = , image_map = Jiangxi in China (+all claims hatched).svg , mapsize = 275px , map_caption = Location ...

, southern China. The specimen consists of the three posteriormost

cervical vertebrae In tetrapods, cervical vertebrae (: vertebra) are the vertebrae of the neck, immediately below the skull. Truncal vertebrae (divided into thoracic and lumbar vertebrae in mammals) lie caudal (toward the tail) of cervical vertebrae. In saurop ...

with two

cervical rib Cervical ribs are the ribs of the neck in many tetrapods. In most mammals, including humans, cervical ribs are not normally present as separate structures. They can, however, occur as a pathology. In humans, pathological cervical ribs are usually no ...

articulated An articulated vehicle is a vehicle which has a permanent or semi-permanent coupling in its construction. This coupling works as a large pivot joint, allowing it to bend and turn more sharply. There are many kinds, from heavy equipment to buse ...

with the first four

dorsal vertebrae In vertebrates, thoracic vertebrae compose the middle segment of the vertebral column, between the cervical vertebrae and the lumbar vertebrae. In humans, there are twelve thoracic vertebra (anatomy), vertebrae of intermediate size between the ce ...

with three dorsal

rib In vertebrate anatomy, ribs () are the long curved bones which form the rib cage, part of the axial skeleton. In most tetrapods, ribs surround the thoracic cavity, enabling the lungs to expand and thus facilitate breathing by expanding the ...

s. In 2023, Mo ''et al''. described ''Jiangxititan ganzhouensis'' as a new genus and species of macronarian sauropod based on these fossil remains. The generic name, "''Jiangxititan''", combines a reference to the type locality in Jiangxi Province with the word "titan", a common suffix for giant sauropod names, referencing the pre-Olympian gods of

Greek mythology Greek mythology is the body of myths originally told by the Ancient Greece, ancient Greeks, and a genre of ancient Greek folklore, today absorbed alongside Roman mythology into the broader designation of classical mythology. These stories conc ...

. The

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

, "''ganzhouensis''", references the discovery of the fossil in Ganzhou City.

Classification

Mo ''et al''. (2023) recovered ''Jiangxititan'' as a derived member of the titanosaurian clade Lognkosauria, as the

sister taxon In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...

to '' Mongolosaurus''. The results of their

phylogenetic analyses In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as Computational phylogenetics, phylogenetic inference. It infers the relationship among organ ...

are shown in the cladogram below: A subsequent analysis by Han and colleagues in 2024 recovered ''Jiangxititan'' as a non-titanosaurian somphospondylan, in a

polytomy An internal node of a phylogenetic tree is described as a polytomy or multifurcation if (i) it is in a rooted tree and is linked to three or more child subtrees or (ii) it is in an unrooted tree and is attached to four or more branches. A tree ...

with several other basal somphospondylans. Removing ''Jiangxititan'' as an unstable

operational taxonomic unit An operational taxonomic unit (OTU) is an operational definition used to classify groups of closely related individuals. The term was originally introduced in 1963 by Robert R. Sokal and Peter H. A. Sneath in the context of numerical taxonomy, wh ...

in their analyses allowed for increased resolution, with more taxa recovered in the

Euhelopodidae Euhelopodidae is a family of sauropod dinosaurs of disputed membership and affinities, which contains '' Euhelopus'' and its close relatives. Most proposed euhelopodids are from East Asia. Euhelopodidae was first recognized by Carl Wiman in 1929 ...

. The reduced consensus tree from their phylogenetic analyses is shown in the cladogram below:

References

{{Taxonbar, from=Q122752684 Titanosauria Dinosaur genera Maastrichtian dinosaurs Taxa named by Xu Xing Fossil taxa described in 2023 Dinosaurs of China