Ceratophrys (Lynch, 1971)

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 : 55-56

Ceratophrys sp. (MLP 88.V.20.1) from the north of the city of Mar del Plata, Buenos Aires, Argentina ( Mercadal de Barrio & Barrio 2002)

A nearly complete skull and left mandible (MLP 88.V.20.1) was collected 1 km north of Mar del Plata ( Fig. 1 , locality 8) in sediments attributed to the Pleistocene Miramar Fm. ( Cione & Tonni 2005; Marshall et al. 1984. These remains were identified as Ceratophrys sp. by Mercadal de Barrio & Barrio (2002).

Osteological features. The morphology of both elements resembles that of all Ceratophrys . The well-ossified skull ( Fig. 5X, Y ) is ornamented but lacks crests. The premaxillae and the posterolateral parts of both maxillary arcades and their suspensory elements are not preserved; thus general cranial proportions cannot be assessed. The squamosal otic plates are subquadrangular, and do not project posterior beyond the level of the occipital condyles ( Fig. 5X ). No teeth are completely preserved. The vomers seem to bear true teeth ( Fig. 5Y ). The lateral margins of the pterygoids are broken; thus, the presence/absence of the ventral process could not be determined. The mandibular bones, including the mentomeckelian bone, are fused one to one another ( Fig. 5Q ). A robust anterior fang is formed by elaboration of both the dentary and mentomeckelian. The dentary is higher than the angulosplenial, protuding from the dorsal margin of this later as a sharpened lamina of bone ( Fig. 5Q ).

Remarks. MLP 88.V.20.1 possesses all the proposed or possible synapomorphies of Ceratophryidae (exostosis, maxilla-squamosal contact, parieto-squamosal arch, expanded squamosal otic ramus overlapping prootic, pars palatina absent on anterior maxilla, spur-like fang formed by mentomeckelian and dentary, mentomeckelian and dentary fused) and Ceratophrys (robust, bar-shaped maxillary processes of nasal, postorbital fenestra) that can be evaluated in the preserved elements. Thus, the generic assignment is justified. Because MLP 88.V.20.1 has a combination of characters that might be plesiomorphic (discussed above), it cannot be assigned to a species of 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.