‘Occitanosaurus’ was described by Sciau et al. (1990) and Bardet et al. (1999). The genus name was erected for ‘Plesiosaurus’ tournemirensis by Bardet et al. (1999). The taxon was originally regarded as an early elasmosaurid but is now considered a member of the Microcleididae. ‘Occitanosaurus’ was approximately 3.9 meters long.
The type material (MMM J. T. 86-100), in the Musée Municipal de Millau, Aveyron, is a nearly complete skeleton including the skull, vertebral series from the atlas-axis to the sacrum, associated ribs, complete pectoral and pelvic girdles, right forelimb, and both hind limbs.
Benson et al. (2012) made ‘Occitanosaurus’ a junior synonym of Microcleidus when they created the new name combination Microcleidus tournemirensis, which is why the genus ‘Occitanosaurus’ is now considered invalid.