Ceratophrys prisca var. subcornuta (MACN 14323) from Farola Monte Hermoso, Buenos Aires, Argentina (Mercadal de Barrio & Barrio, 2002)

Mercadal de Barrio & Barrio (2002) listed this specimen as Ceratophrys prisca var. subcornuta . This variety, erected by Rovereto (1914), is not currently valid (Fernicola 2001, see above). The label and records associated with MACN 14323 identify it as Ceratophrys prisca from “Monte Hermoso, Piso Montehermosense”; presumably, the specimen came from the Mio-Pliocene sediments of Farola Monte Hermoso (Fig. 1, locality 4), Buenos Aires, Argentina.

Osteological features. MACN 14323 is an incomplete skull (Fig. 5 M−L) that generally resembles those of all other Ceratophrys . The specimen is too fragmentary to assess its proportions. The preservation of this specimen, along with the material used to repair and glue some of its parts, obscure the posterior region of the frontoparietals and their contact with the squamosals (Fig. 5M). However, a parieto-squamosal arch is present on the left side of the skull (Fig. 5M), and it is apparent from the preserved medial margin of the left squamosal otic plate and the posterolateral margin of the right frontoparietal that a postorbital fenestra was present.The squamosal otic plate extends to the level of the occipital condyles, but its posterolateral portion is broken. The broken edge is broad, suggesting that the plate may have projected far posteriorly. The preserved portion has a concave dorsal surface. A lateral wall is well developed (Fig. 5L). The squamosal and pars facialis of the maxilla seem to bear a crest, but it is difficult to be certain owing to the poor preservation of the fossil. Ventrally, a discrete pars palatina is absent (Fig. 5N).

Remarks. These remains have all the proposed or possible synapomorphies of Ceratophryidae (exostosis, parieto-squamosal arch, expanded squamosal otic ramus overlapping prootic, anterior maxillary pars palatina absent) and Ceratophrys (robust, bar-like maxillary process of nasal, postorbital fenestra) that can be evaluated. However, they are too fragmentary to attribute them to a species in Ceratophrys .