Ceratophrys prisca var. subcornuta

Nicoli, Laura, 2019, The fossil record of Ceratophrys Wied-Neuwied (Anura: Ceratophryidae): a revision and update of fossil South American horned frogs, Zootaxa 4658 (1), pp. 37-68 : 55

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 .

Figures

FIGURE 1. Distributional map of extant and fossil Ceratophrys. The phylogeny of the extant species of Ceratophyrs were proposed by Faivovich et al.(2014). The numbers in circles represent the fossiliferous localities mentioned in the article: 1, Arroyo Chasicó; 2, Arroyo Tapalqué; 3, Conchillas; 4, Farola Monte Hermoso; 5, Fortín Necochea; 6, Lagoa Santa; 7, Laguna de Los Tres Reyes; 8, Mar del Plata and Miramar cities; 9, Ñuapua; 10, Olivos; 11, Puerta de Corral Quemado; 12, Quehué; 13, San Antonio and Paso Alsina; 14, Tarija. Black circles: localities where the presence of Ceratophrys was confirmed; white circles: the presence of Ceratophrys remains unconfirmed. The distributions of the extant species of Ceratophrys are represented by areas that approximately include all the reported records for each species; the distribution of most species, however, is not well known. Distributions are based on Lynch (1982) with corrections and additions from Barrio-Amorós 2004; Barrio 1980; Langone 1995; Maciel et al. 2013; Maneyro & Langone 2001; Ortiz et al. 2013; Peters 1967; Rivero 1961; Stuart et al. 2008.

FIGURE 5. Neogene fossils attributed to Ceratophrys. A–K, fossils from the vicinities of the cities of Mar del Plata on the Atlantic Cost of the province of Buenos Aires, Argentina, attributed to Ceratophrys sp. by Mercadal de Barrio & Barrio (2002); A, B, MLP 34.V.10.8: nearly complete right maxilla; C, D, MACN 17585 anterior portion of left maxilla; E–G, MACN 17936: fragments of posterior skull roof (E, F) and neurocranium (G); H–K, MACN 18074: fragments of a left maxilla (H, I) and right squamosal (J, K). M–L, MACN 14323: fragmentary skull from Farola Monte Hermoso, Argentina, attributed to C.prisca var. subcornuta by Mercadal de Barrio & Barrio (2002). O, P, MNHN 1560: maxilla from the Conchillas Locality (Fig 2, locality 2), Colonia, Uruguay, attributed to Ceratophrys sp. by Rinderknecht (1998). Q–Y, MLP 88.V.20.1: skull (X, Y) and left mandible (Q) from the north of Mar del Plata, Argentina, attributed to Ceratophrys sp. by Mercadal de Barrio & Barrio (2002).A, D, I, O, labial views; B, C, H, P, Q, lingual views; E, J, M, X, dorsal views; F, G, N, ventral views; K, L, lateral views. Abbreviations: as, angulosplenial; d, dentary; fp, frontoparietal; ppa, discrete pars palatina absent; lc, lateral crest; mk, mentomeckelian; mop, material of preparation; mp, maxillary process of nasal; mpp, maxillary process ofpremaxilla; mps, socket that would receive the maxillary process of premaxilla; ncs, socket that would have received the ossification of the nasal cartilages; oc, occipital condyle; otc, otic capsule; pas, socket that would have received the ossifications of the planum antorbitale; pf, pars facialis; pof, space delimiting by the showed bone that corresponds to the postorbital fenestra; pp,pars palatina; ppa, discrete pars palatina absent; psa, portion of the showed bone that forms the parieto-squamosal arch; psf, parasphenoid; pt, pterygoid; ptp, pterygoid process; qj, quadratojugal; th, teeth; slw, squamosal lateral world; sop, squamosal otic plate; sf, space delimiting by the showed bone that corresponds to the subtemporal fenestra; v, vomer; vr, squamosal ventral ramus; zr, squamosal zygomatic ramus. Scale bar is 5 mm.