Open Paleo

Rayososaurus

Bonaparte, 1996 rie-YOH-soh-SAWR-us

Named after the Rayoso Formation in Neuquén Province, Argentina, where the specimen was excavated, combined with Greek 'sauros' (lizard).

100.5–93.9 million years ago Cenomanian, Late Cretaceous
Late Cretaceous stages

Rayososaurus is an extinct genus of sauropod dinosaur in the family Rebbachisauridae. Rayososaurus was named by Argentinian paleontologist José Bonaparte in 1996. Its type and only accepted species is Rayososaurus agrioensis. The species Limaysaurus tessonei was at one point included in Rayososaurus as Rayososaurus tessonei.

Under dispute

Rayososaurus is a valid rebbachisaurid distinct from Limaysaurus, from which it was separated when the species formerly referred to it was moved to the new genus Limaysaurus (Salgado and colleagues, 2004). Its position within Rebbachisauridae is poorly constrained owing to its fragmentary holotype: it has been recovered within Limaysaurinae (Carballido and colleagues, 2012), and is frequently excluded from analyses.

Diagnosis

  1. Scapular acromion process very well developed and directed markedly posteriorly
  2. Ventral margin of the scapular blade with a strong, pointed, ventrodistally directed expansion
  3. V-shaped angle between the acromion process and the dorsodistal margin of the scapular blade

Species

Rayososaurus agrioensis Bonaparte, 1996

Type species

Named for the Agrio River near which the holotype was found, in Neuquén Province, Argentina.

Holotype
MACN-N 41 , Museo Argentino de Ciencias Naturales ‘Bernardino Rivadavia’
Material
A left scapula lacking the distal blade, an almost complete right scapular blade, the distal three-quarters of a left femur, and the proximal half of a left fibula.
Horizon
upper Candeleros Formation, Cenomanian, Late Cretaceous , 100.5–93.9 million years ago
Locality
Agrio del Medio, Neuquén, Argentina The genus is named for the Rayoso Formation, which Bonaparte (1996) gave as the holotype's unit. Carballido and colleagues (2010) relocated the excavation site and matched the matrix adhering to the bones to the Candeleros on grain size, sorting and muddy matrix, ruling the Rayoso out.

References

  1. Bonaparte, J. F. (1996). Cretaceous tetrapods of Argentina. Münchner Geowissenschaften Abhandlungen 30: 73-130. bonaparte1996a
  2. Carballido, J. L.; Garrido, A. C.; Canudo, J. I.; Salgado, L. (2010). Redescription of Rayososaurus agrioensis Bonaparte (Sauropoda, Diplodocoidea), a rebbachisaurid from the early Late Cretaceous of Neuquén. Geobios 43(5): 493-502. doi:10.1016/j.geobios.2010.01.004

    Redescription of the type species, Rayososaurus agrioensis.

    carballido2010a
  3. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Sauropods. Princeton University Press.

    Source of the body length and hip height estimates.

    jones2026b
  4. Carballido, J. L.; Salgado, L.; Pol, D.; Canudo, J. I.; Garrido, A. (2012). A new basal rebbachisaurid (Sauropoda, Diplodocoidea) from the Early Cretaceous of the Neuquén Basin; evolution and biogeography of the group. Historical Biology 24(6): 631-654. Informa UK Limited. doi:10.1080/08912963.2012.672416

    Recovers Rayososaurus-referred material within Limaysaurinae in rebbachisaurid phylogenetic analysis

    carballido2012a
  5. Salgado, L.; Garrido, A.; Cocca, S. E.; Cocca, J. R. (2004). Lower Cretaceous rebbachisaurid sauropods from Cerro Aguada del León (Lohan Cura Formation), Neuquén Province, northwestern Patagonia, Argentina. Journal of Vertebrate Paleontology 24(4): 903-912. Informa UK Limited. doi:10.1671/0272-4634(2004)024[0903:lcrsfc]2.0.co;2

    Bearing on the separation of Rayososaurus from Limaysaurus.

    salgado2004a