Riojavenatrix represents one of five known spinosaurid taxa from the Iberian Peninsula, the others being Camarillasaurus, Iberospinus, Protathlitis, and Vallibonavenatrix.

The holotype of Riojavenatrix is a fragmentary dorsal vertebra, pelvic girdle, and hindlimb elements that were initially assigned to Baryonyx.

Apparently, all the material belonged to the same individual because it was recovered in association with bones of consistent size and no duplicated elements.

The generic name, Riojavenatrix, comes from La Rioja province in Spain, plus the Latin venatrix, meaning "huntress".

[1] The following cladograms illustrate the results of the analyzes obtained by the authors of the Riojavenatrix description using different data sets.