Ceratophys, Gray, 1831

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 : 60

Ceratophys sp. (FCS PA1.E1.P4.1; SA1.M3.590.1−2; SA1.S1.486.1; 506.1; 525.1; 534.1) from archeological localities in the lower valley of the Colorado River, Buenos Aires, Argentina ( Stoessel et al. 2008)

A series of disarticulated skull bones from the archeological localities of San Antonio and Paso Alsina, in the Partido of Villarino in the province of Buenos Aires, Argentina, was identified as Ceratophrys sp. by Stoessel and collaborators (2008). L. Stoessel (FSC) graciously provided photographs of the most complete material. The fossiliferous sediments are thought to have been deposited between 1500 and 400 years BP, based on isotopic dating and the ceramics found therein.

Osteological features. The most complete remains (illustrated by Stoessel and collaborators in 2008) consist of a fragmentary nasal (originally interpreted as a frontoparietal by Stoessel et al. 2008: fig 2A), frontoparietal, premaxilla, and maxilla ( Stoessel et al. 2008: fig 2). Each element, except the premaxilla, is ornamented. The nasal ( FCS SA 1.S1.506.1) is a robust bone that seems to have articulated with other elements along its medial and posteri- or margins. The posterior margin is oblique to the midline. A robust, but incomplete, maxillary process is evident.

The frontoparietal ( FCS SA 1.S1.525.1) is robust and seems to have articulated with other bones along its medial and anterior margins ( Stoessel et al. 2008: fig 2B). At about its longitudinal midpoint, the frontoparietal bears a robust lateral projection that probably represents the medial portion of the parieto-squamosal arch; this projection and the posterolateral margin of the bone seem to delimit a postorbital fenestra.

The alary process of the premaxilla ( FCS SA 1.M3.590.1) is broken ( Stoessel et al. 2008: fig 2C, D). The basal portion is flat. A pars palatina (or palatine process) is absent and the maxillary process is long and bar-shaped.

The pars facialis of the maxilla ( FCSPA 1.E1.P4.1) is high ( Stoessel et al. 2008: fig 2G, H). In lingual view, there is an anterior socket with which the maxillary process of the premaxilla presumably articulated. The anterior half of the bone lacks a pars palatina, but posteriorly, bears a well-developed pterygoid process that seems to have been triangular.

Remarks. Although it is impossible to determine whether these elements belonged to the same individual, it was possible to confirm the presence of all the proposed or possible synapomorphies of Ceratophryidae and Ceratophrys , as they follow: exostosis; nasal with robust bar-shaped maxillary processes; parieto-squamosal arch delimiting a postorbital fenestra; flat premaxillary alary processes; absence of pars palatina (and palatine process) on the premaxilla and anterior half of the maxilla; and long, bar-shaped maxillary process on the premaxilla. Thus, the generic placement of this material in Ceratophrys is well supported.