Thursday, February 25, 2021

[Paleontology • 2021] Dzharatitanis kingi • First Rebbachisaurid Sauropod Dinosaur from Asia

Dzharatitanis kingi 
Averianov & Sues, 2021

Dzharatitanis kingi gen. et sp. nov. is based on an isolated anterior caudal vertebra (USNM 538127) from the Upper Cretaceous (Turonian) Bissekty Formation at Dzharakuduk, Uzbekistan. Phylogenetic analysis places the new taxon within the diplodocoid clade Rebbachisauridae. This is the first rebbachisaurid reported from Asia and one of the youngest rebbachisaurids in the known fossil record. The caudal is characterized by a slightly opisthocoelous centrum, ‘wing-like’ transverse processes with large but shallow PRCDF and POCDF, and the absence of a hyposphenal ridge and of TPRL and TPOL. The neural spine has high SPRL, SPDL, SPOL, and POSL and is pneumatized. The apex of neural spine is transversely expanded and bears triangular lateral processes. The new taxon shares with Demandasaurus and the Wessex rebbachisaurid a high SPDL on the lateral side of the neural spine, separated from SPRL and SPOL. This possibly suggests derivation of Dzharatitanis from European rebbachisaurids. This is the second sauropod group identified in the assemblage of non-avian dinosaurs from the Bissekty Formation, in addition to a previously identified indeterminate titanosaurian.

Fig 1. Dzharatitanis kingi, USNM 538133 (holotype), anterior caudal vertebra
in posterior (A), right lateral (B), and anterior (C) views.
Scale bar = 10 cm.

Systematic paleontology
Sauropoda Marsh, 1878 
Neosauropoda Bonaparte, 1986 
Diplodocoidea Marsh, 1884 
Rebbachisauridae Bonaparte, 1997 

Genus Dzharatitanis gen. nov.
Diagnosis: Differs from Limaysaurus and Tataouinea by convex anterior centrum articular surface. Differs from Lavocatisaurus and Limaysaurus by absence of pleurocoel on centrum. Differs from Comahuesaurus by ‘wing-like’ transverse process. Differs from Amazonsaurus by dorsally directed ventral surface of transverse process. Differs from Cathartesaura, Comahuesaurus, Demandasaurus, Itapeusaurus, and Tataouinea by shallow PRCDF. Differs from Cathartesaura, Itapeusaurus, Katepensaurus, and Tataouinea by absence of TPRL. Differs from Comahuesaurus, Demandasaurus, and Nigersaurus by absence of ventral contact between prezygapophyses. Differs from Comahuesaurus, Demandasaurus, Itapeusaurus, Limaysaurus, Nigersaurus, and Tataouinea by absence of ventral contact between postzygapophyses. Differs from Demandasaurus and Tataouinea by absence of hyposphenal ridge. Differs from Amazonsaurus, Cathartesaura, Katepensaurus, Limaysaurus, Nigersaurus, and Tataouinea by absence of SPRL and SPOL contact. Differs from Amazonsaurus, Cathartesaura, Katepensaurus, Limaysaurus, Nigersaurus, Tataouinea, and Rebbachisaurus by large SPDL on lateral side of neural spine separate from SPRL and SPOL. Differs from Amazonsaurus, Cathartesaura, Comahuesaurus, Itapeusaurus, Lavocatisaurus, and Limaysaurus by presence of lateral process of neural spine. Differs from Rebbachisaurus by proximodistally shorter and anteroposteriorly wider neural spine, which is convex anteriorly in lateral view, and by much wider PRSL.
Occurrence: Central Asia; Late Cretaceous (Turonian).

Etymology: From the Dzharakuduk locality in Uzbekistan and Greek τιτάν (titan), a pre-Olympian god in ancient Greek mythology. The generic name is in the feminine gender.

Dzharatitanis kingi sp. nov. 
 2015 Titanosauria indet.: figure 7 in [2].

Holotype: USNM 538127, nearly complete anterior caudal vertebra. Found by David J. Ward and Hans-Dieter Sues during the URBAC (Uzbekistan/Russian/British/American/Canadian) joint paleontological expedition working in Uzbekistan in 1997.

Type locality and horizon: Dzharakuduk, 32 km SW of Mynbulak, Navoi Viloyat, Uzbekistan. The Bissekty Formation, exposed along the Dzharakuduk escarpment, extends from approximately 42°06’22.60’’ N and 62°37’09.00’’ E to 42°05’44.22’’ N and 62°41’06.49’’ E. Age: Late Cretaceous (Turonian). For additional geological details see Redman and Leighton [5].

Etymology: In memory of our colleague and friend Dr. Christopher King (1943–2015) who did much work on the geology of Cretaceous strata in Central Asia.

Remarks: USNM 538127 is likely the first caudal vertebra because of its slightly opisthocoelous centrum and the absence of chevron facets. First caudals with opisthocoelous centra are known for several rebbachisaurids (see Comparison).

Alexander Averianov and Hans-Dieter Sues. 2021. First Rebbachisaurid Sauropod Dinosaur from Asia.   PLoS ONE. 16(2): e0246620. DOI: 10.1371/journal.pone.0246620

New diplodocus-like dinosaur from Uzbekistan as the first rebbachisaurid found in Asia.