Notoetayoa, Gelfo, Lopez, and Bond, 2008

Genus NOTOETAYOA Gelfo, López, and Bond, 2008

Type species. Notoetayoa gargantuai Gelfo, López, and Bond, 2008

Figure 7 View FIGURE 7 A-C

Assigned material. UNPSJB PV766 isolated left p2.

Geographic and stratigraphic provenance. The tooth was found at “Tiro Federal Coronel Pringles” by Mónica Abril in Gaiman locality, Chubut province, and comes from the white to pink arkosic sandstone of the Rio Chico Group. This level was assigned to Las Flores Formations (Chornogubsky et al., 2023).

Comments. The specimen was preliminarily identified in the collection of UNPSJB as a p2 of Carodnia . Considering the common presence in the Carodnia zone of C. feruglioi and Notoetayoa gargantuai (Gelfo et al., 2008) , the similitude of UNPSJB PV766 with the p2 Etayoa bacatensis , the differences with known p2 of C. feruglioi and C. vieirai , and their size, is here assigned to N. gargantuai .

Description and comparisons. The tooth exhibits similarities to the p2 of Etayoa bacatensis (GM-32) than to any other SANU, in terms of its labiolingual compression, presence of two mesiodistally aligned roots, a robust and centrally positioned protoconid, and a relatively short and simplified talonid ( Figure 7 View FIGURE 7 D-F). These characteristics distinguish it from those of Carodnia feruglioi and C. vieirai . However, it differs from E. bacatensis in its substantially larger size and the absence of cusps in the talonid. The specimen displays a translucent and thin enamel, albeit with surface roughness. Although the roots are missing, there are indications of the presence of two roots, the mesial one larger, as the condition observed in Etayoa (Villarroel, 1987) . The tooth is labiolingually compressed, with its main axis oriented mesiodistally (16.25 mm x 8.94 mm) and a strong labial wear facet over the enamel of the distal side, which is similar in position and orientation to the hy-mb wear facet in the p2 of Carodnia feruglioi (MLP-PV 34-V-22-8, Figure 3I View FIGURE 3 ), and is here considered homologous to it base on its position since no hypoconid could be identified ( Figure 6 View FIGURE 6 B-C: hd-b). The protoconid is the only identifiable cusp, slightly rounded at the base, with a flat wear surface (i.e., prcd-h), and the distal and mesial cristids are present. A strong paracristid descends mesially from the apex of the protoconid and in occlusal view, bends a bit lingually before reaching a small elevation from which two structures depart. The first is an almost vertical cristid in the mesial side of the tooth, and the other is a strong and crenulated precingulid that continues in a lingual cingulid and surrounds the base of the protoconid. In lateral view, the paracristid is a high ridge that forms a mesial and convex blade. A distal cristid, partially broken, also descends from the protoconid apex but not with such an abrupt angle as in the paracristid. Distally, it turns lingually down to the base in a postcingulid. The possible contact of the postcingulid and the lingual cingulid cannot be determined since the enamel is broken.

In addition to its larger size, there exist other distinguishing features between the p2 of Notoetayoa and Etayoa bacatensis ( Figure 7 View FIGURE 7 ). These distinctions include a notably more pronounced mesial bifurcation of the paracristid and the presence of a well-developed lingual cingulum in Notoetayoa . Conversely, the distal portion of the p 2 in E. bacatensis is wider and displays two cusps as described by Villarroel (1987), a distal and lower cusp, here identified as the hypoconid ( Figure 7 View FIGURE 7 E- F), and on its lingual side, a faint bump, which, regrettably, could not be corroborated in our photographs or casts. This latter feature may be homologous to the entoconid of the p2 found in Carodnia feruglioi ( Figure 3C View FIGURE 3 ).

The p2 of Notoetayoa also differs from the p2 of C. feruglioi and C. vieirai . Despite the paracristid in these species being shorter and bifurcates mesially as in Notoetayoa , the precingulid is strong in C. feruglioi and extends in a short portion labially and lingually ( Figure 3C View FIGURE 3 ), while in C. vieirai (DGM 334) is a sharp ridge with the lingual portion of the precingulid more extended over the base of the protoconid. Probably the vertical cristid here identified in Notoetayoa is homologous to the labial component of the precingulid in Carodnia , but with a modified position consequence of the lingual bend of the paracristid. Other differences with Notoetayoa rest in the further development of the talonid cups in the Carodnia species.