Ceratophrys cf. ornata (Fernicola, 2001)

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 : 56

Ceratophrys cf. ornata (MLP 86.VIII.1.5) and Ceratophrys sp. (MLP 86.VIII.1.1; 86.VIII.1.6) from Laguna Los Tres Reyes Locality, Buenos Aires, Argentina ( Perí 1993a)

Three crania are partially preserved from Laguna Los Tres Reyes Locality ( Fig. 1 , locality 7) in the Partido of Gonzales Chaves, province of Buenos Aires, Argentina; these were illustrated and attributed to Ceratophrys by Perí (1993a). The fossil-bearing sediments correspond to the upper part of the Fm. La Postrera, which was deposited during the Late Pleistocene–Holocene ( Fidalgo et al. 1991; Perí 1993a).

Osteological features. A nearly complete skull ( MLP 86. VIII.1.1 [ Perí 1993a: lam. I, fig. 1]) lacks the premaxillae. Its general morphology resembles that of extant Ceratophrys . The greatest height of the skull is less than half of its greatest width. Cranial crests are absent. The squamosal otic plate is subquadrangular and extends to the level of the occipital condyles. Dentate vomers and neopalatines with conspicuous odontoid ridge are present.

The skull of MLP 86. VIII.1.5 ( Perí 1993a: lam. I, fig.1) is incomplete; the anterior portion is missing, along with and the posterior regions of both suspensoria. Although no general proportions can be estimated, the general structure of the preserved elements resemble those of extant Ceratophrys . Cranial crests are absent. The squamosal otic plate is subquadrangular and reaches the level of the occipital condyles. The associated columella ( Fig. 6A ), reported as preserved in situ by Peri (1993a), now is disarticulated. It has two distinctive apophyses, as has been described (and observed) in C. cranwelli and C. ornata ( Fig. 6B ; Perí 1993a). The vomers are dentate and the neopalatines have a conspicuous odontoid ridge.

MLP 86. VIII.1.6 (Perí 199a3: lam. I, fig. 3) is an incomplete skull composed of the interorbital region, a partial maxilla and pterygoid, the ossified planum antorbitale, and nasal cartilages and their associated dermal bones. No general proportions can be estimated. The morphological features of the remains resemble those of living Ceratophrys . Dentate vomers and neopalatines with conspicuous odontoid ridge are present.

Remarks. All proposed or possible synapomorphies of Ceratophryidae and Ceratophrys that can be observed in the preserved regions of the skulls from Laguna Tres Reyes are present in these remains ( MLP 86. VIII.1.1.—exostosis, non-pedicellate monocuspid teeth, squamosal-maxilla contact, parieto-squamosal arch; absence of pars palatina on anterior maxilla [ Ceratophryidae ]; robust, bar-shaped maxillary processes of nasals, postorbital fenestra [ Ceratophrys ]. MLP 86. VIII.1.5.—exostosis, non-pedicellate monocuspid teeth, squamosal-maxilla, parieto-squamosal arch, absence of pars palatina on anterior maxilla [ Ceratophryidae ]; robust, bar-shaped maxillary processes of nasals; postorbital fenestra [ Ceratophrys ]. MLP 86. VIII.1.6.—exostosis, non-pedicellate monocuspid teeth, squamosal-maxilla contact, absence of pars palatina on anterior maxilla [ Ceratophryidae ]; robust, bar-shaped maxillary processes of nasals [ Ceratophrys ]).Thus, the generic assignment is well supported, but the remains cannot be identified to species.

Perí (1993) described the columella associated with MLP 86. VIII.1.5 to be monocapitate and on that basis, she attributed this fossil to Ceratophrys cf. ornata . In contrast, I think that this columella is bicapitate. Given the observed intraspecific variation in this feature in Ceratophrys (discussed above), I do not think this character is species specific.

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 6. Quaternary fossils attributed to Ceratophrys. A, fossil columella (MLP 86.VIII.1.5) from Laguna Los Tres Reyes Locality, province of Buenos Aires, Argentina, attributed Ceratophrys cf. ornata by Perí (1993). B, columella of C. cranwelli (FML 5475). C–G, two incomplete skulls (C–E) and a premaxilla (F, G) from Ñuapua, Bolivia, attributed to Ceratophrys cf. ornata by Vergnaud-Grazzini (1968). H–K, fossils from the Arroyo Tapalqué locality, Buenos Aires, Argentina, listed as Ceratophrys sp. by Mercadal de Barrio & Barrio (2002); H–J, MLP 86.III.25.150: squamosal (H) and right maxilla (I, J); K, MLP 86.III.25.151: frontoparietals. A,C, H, K, dorsal views; B, ventral views; D, J, lingual views; E, I, labial views. Abbreviations: as, angulosplenial; d, dentary; fp, frontoparietal; pp, premaxillary palatine process; 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 planumantorbitale; 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 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.