Tharosaurus
Named for the Thar Desert of Rajasthan, India, where the holotype was found, combined with Greek 'sauros' meaning 'lizard'.
Tharosaurus is an extinct genus of potentially dubious eusauropod sauropod dinosaurs from the Middle Jurassic Jaisalmer Formation of India. The genus contains a single species, Tharosaurus indicus, known from a fragmentary skeleton including several vertebrae and a rib. When it was named in 2023, Tharosaurus was interpreted as the earliest known diplodocoid and the first member of this clade described from India. However, a later revision of the fossil material argued for a position outside of this clade, as an indeterminate eusauropod. This revision could not find unique features in the Tharosaurus specimen, so it was classified as a nomen dubium.
Under dispute
Tharosaurus was described as the oldest known dicraeosaurid (Bajpai and colleagues, 2023), a placement followed by Jones (2026), but Mannion and Moore (2025) reject the diplodocoid identification and reinterpret it as a nomen dubium representing an indeterminate eusauropod outside Turiasauria and Neosauropoda.
Diagnosis
- Middle/posterior cervical centroprezygapophyseal lamina divided into lateral and medial branches with medial branch connecting to intraprezygapophyseal lamina
- Middle/posterior cervical centropostzygapophyseal fossa elliptical and bordered laterally by pillar-like centropostzygapophyseal laminae
- Deep bifurcation of cervical neural arch extending to dorsal margin of neural canal
- Paired fossae on ventral surface of middle/posterior cervical centrum separated by mid-line keel
- Anterior condyle of middle/posterior cervical more rugose compared to rest of centrum
- Bifid middle/posterior cervical neural spine
- Divided lateral fossa/pleurocoel on cervical centra
- Lateral fossa divided into deep posterior and shallow anterior half by weak ridge
- Prominent lateroventral flanges on middle/posterior cervical centrum
- Middle/posterior cervical vertebrae with pre-epipophysis
- Cordiform cross-section of anterior caudal centra
- Middle/posterior dorsal transverse process laterally directed
- Middle caudal centra articular surface with flat ventral margin
- Ventral surface of mid-caudal centrum with deep median fossa
Species
Tharosaurus indicus Bajpai et al., 2023 Disputed
Type species
From Latin 'indicus' meaning 'of India', referring to the discovery of the holotype in Rajasthan, India.
- Holotype
- RWR-241A, RWR-241B, RWR-241C, RWR-241D, RWR-241E, RWR-241F, RWR-241G, RWR-241H, RWR-241I, RWR-241J, RWR-241K , Geological Survey of India
- Material
- Partial middle/posterior cervical vertebra; middle/posterior cervical anterior condyle and right prezygapophyses; partial anterior dorsal neural arch; middle/posterior neural spines; anterior dorsal rib; partial anterior and middle caudal vertebrae.
- Horizon
- Fort Member, Jaisalmer Formation, Bathonian, Middle Jurassic , 168.2–165.3 million years ago
- Locality
- Jethwai village, Rajasthan, India
References
- Bajpai, S.; Datta, D.; Pandey, P.; Ghosh, T.; Kumar, K.; Bhattacharya, D. (2023). Fossils of the oldest diplodocoid dinosaur suggest India was a major centre for neosauropod radiation. Scientific Reports 13(1). Springer Science and Business Media LLC. doi:10.1038/s41598-023-39759-2 bajpai2023a
-
Mannion, P. D.; Moore, A. J. (2025). Critical reappraisal of a putative dicraeosaurid sauropod dinosaur from the Middle Jurassic of Gondwana and a revised view of diplodocoid evolutionary relationships and biogeography. Journal of Systematic Palaeontology 23(1): 2550760. Informa UK Limited. doi:10.1080/14772019.2025.2550760
Rejected the diplodocoid identification of Tharosaurus, reinterpreting it as a nomen dubium, an indeterminate eusauropod outside Turiasauria and Neosauropoda.
mannion2025a -
Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Sauropods. Princeton University Press.
Source of the body length, mass, and hip height estimates, and the appearance features.
jones2026b