 In 2016, a well-preserved specimen of "R. equinus" was described by Martínez et al.from the Sarmiento Formation in Patagonia.The extraordinary preservation of the specimen allowed the researchers to appreciate the three connected spaces that constitute a heavily pneumatized middle ear; the epitympanic sinus, the tympanic cavity itself, and the ventral expansion of the tympanic cavity through the notably inflated bullae.