Open Paleo

Abdarainurus

Averianov & Lopatin, 2020 ab-duh-RAY-noo-rus

Named after Abdrant Nuru, the holotype locality in Mongolia, combined with Latin 'urus' meaning 'tail'

83.6–72.2 million years ago Campanian, Late Cretaceous
Late Cretaceous stages

Abdarainurus is a genus of titanosaur dinosaur from the Alagteeg Formation in Mongolia. The type and only species is A. barsboldi. Currently seen as an indeterminate titanosaur, it may represent a previously unknown lineage of Asian macronarians. Abdarainurus is not known from many remains; it is only known from eight front tail vertebrae and a middle tail vertebra and several chevrons.

Under dispute

Placed at Somphospondyli incertae sedis. Abdarainurus is known only from highly unusual caudal vertebrae, including opisthocoelous anterior and middle caudals otherwise seen in Opisthocoelicaudia, and was erected as Titanosauria incertae sedis (Averianov and Lopatin, 2020). Their preferred (implied weighting) analysis recovers a basal titanosaur, as does the most recent dedicated analysis (Han and colleagues, 2024, which recovers it as sister to Gandititan), but the equal-weighting strict consensus of the erecting paper allows a non-titanosaurian somphospondylan position. Somphospondyli is the least-inclusive clade all these hypotheses accept.

Diagnosis

  1. Anterior and middle caudal centra opisthocoelous (convex anterior, concave posterior articular surfaces)
  2. Longitudinal ridges on the medial walls of the neural canal in anterior caudal vertebrae, not previously reported in any sauropod
  3. Postprezygapophyseal process: a distinct spine-like process on the medial side of the prezygapophysis posterior to the articular surface, unique among sauropods
  4. Postspinal fossa of anterior caudals hypertrophied and funnel-like, with very high spinopostzygapophyseal laminae
  5. Neural spine of anterior caudals mediolaterally constricted, narrower than the pre- and postspinal laminae
  6. Spinodiapophyseal fossa at the base of the anterior caudal neural spine partially covered laterally by a high postzygodiapophyseal lamina, forming a deep pocket

Species

Abdarainurus barsboldi Averianov & Lopatin, 2020

Type species

Named in honor of Rinchen Barsbold, the Mongolian paleontologist and academician.

Holotype
PIN 5669/1 , Paleontological Institute, Russian Academy of Sciences
Material
Series of eight anterior and one middle caudal vertebrae and associated chevrons.
Horizon
Alagteeg Formation, Campanian, Late Cretaceous , 83.6–72.2 million years ago
Locality
Abdrant Nuru, Ömnögovi, Mongolia

References

  1. Averianov, A. O.; Lopatin, A. V. (2020). An unusual new sauropod dinosaur from the Late Cretaceous of Mongolia. Journal of Systematic Palaeontology 18(12): 1009-1032. Informa UK Limited. doi:10.1080/14772019.2020.1716402

    Erecting paper; recovered Abdarainurus as a basal titanosaur under implied weighting, but as a non-titanosaurian somphospondylan under equal weighting.

    averianov2020a
  2. Han, F.; Yang, L.; Lou, F.; Sullivan, C.; Xu, X.; Qiu, W.; Liu, H.; Yu, J.; Wu, R.; Ke, Y.; Xu, M.; Hu, J.; Lu, P. (2024). A new titanosaurian sauropod, Gandititan cavocaudatus gen. et sp. nov., from the Late Cretaceous of southern China. Journal of Systematic Palaeontology 22(1): 2293038. Informa UK Limited. doi:10.1080/14772019.2023.2293038

    Recovered Abdarainurus within Titanosauria as the sister taxon of Gandititan.

    han2024a
  3. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Sauropods. Princeton University Press.

    Source of the body length, mass, and hip height estimates.

    jones2026b