Cairanoolithus

Cairanoolithus Temporal range: Late Cretaceous PreЄ Є O S D C P T J K Pg N
Cairanoolithus dughii
Eggshell classification
Basic shell type:	†Dinosauroid-spherulitic
Oofamily:	†Cairanoolithidae
Oogenus:	†Cairanoolithus
Oospecies
C. roussetensis Vianey-Liaud et al., 1994 C. dughii (type) Vianey-Liaud et al., 1994
Synonyms
Dughioolithus Vianey-Liaud et al., 1994

Cairanoolithus is an oogenus of dinosaur egg.^[1][2]

Distribution

Cairanoolithus is native the late Campanian to early Maastrichtian of Southwestern Europe, including southern France and northern Iberia.^[2] They are found in the Aix Basin below the Rognac Limestone.^[2][3] C. dughii is from the La Caraine site in Bouches du Rhône, France, from Roquehautes-Grand Creux and from the Villeveyrac Basin.^[3] C. roussetensis is native to Rousset Village, Roquehautes-Crete du Marbre, Villeveyrac Basin, and Argelliers-Montamaud.^[3]

History

The Aix-en-Provence Basin was first excavated for fossils in 1869 by French paleontologist Philippe Matheron.^[4] In the 1950s, Dughi and Sirugue worked on the basin studying fossil eggshells. They divided the eggs they had found into ten different types, but they did not describe them in detail. In the 70s and 80s, further work was done by Kerourio and Erben.^[3]

Cairanoolithus eggs were described (but not named) by M. M. Penner in his 1983 doctoral thesis.^[2] They were not named until 1994, when French paleontologists M. Vianey-Liaud, P. Mallan., O. Buscail and C. Montgelard, who described the two Cairanoolithus oospecies: Cairanoolithus dughii and "Dughioolithus" roussetensis.^[3] Following further discoveries in 2001, Géraldine Garcia and Monique Vianey-Liaud synomized the two oogenera.^[5] These oospecies received very little attention from the scientific literature, until 2015 when Albert G. Selles and Angel Galobart did a comprehensive reanalysis of Cairanoolithus, in which they reclassified Cairanoolithus into a new oofamily, Cairanoolithidae, and novelly interpreted it as the eggs of a nodosaur.^[2]

Paleobiology

A 1915 restoration of Struthiosaurus, the possible parent of Cairanoolithus

Cairanoolithus has long been considered to be eggs of titanosaurs or ornithopods (like Rhabdodon)^[6][7] The cladistic analysis by Sellés and Galobart in 2015 concluded it was an ornithischian. They analyzed the pelvis of Rhabdodon, the largest ornithopod from Southwestern Europe, and found that it could not have laid eggs as large as Cairanoolithus. Therefore, they considered Cairanoolithus to be the eggs of a nodosaur, like Struthiosaurus, since these are the only other ornithischians known from Southwestern Europe at the time. They also analyzed the pelvis of Struthiosaurus and found that, even though it was relatively small, it could easily lay eggs the size of Cairanoolithus because of the unique orientation of its ischia.^[2]

References