Hippidion sp.

Hippidion sp.

( Fig. 8C View Fig 1–H View Fig 2 View Fig ).

Referred material

Left maxilla with four molariforms and two?right isolated molariforms ( MHNG GEPI V-3779), two right M3 ( PIMUZ A/ V 4115, 4238), left dP2 ( PIMUZ A/ V 4239), left?M2 ( PIMUZ A/ V 4198) and left M3 ( PIMUZ A/ V 4222), right p3 or p4 ( PIMUZ A/ V 4220), left p3 or p4 and ( PIMUZ A/ V 4197), and p2 or p3 ( PIMUZ A/ V 4219), right m3 ( PIMUZ A/ V 4240), and left first phalanges ( PIMUZ A/ V 4205). Geographic data of the specimens are provided in Additional file 1.

Description and comparisons

Te left maxilla MHNG GEPI V-3779 ( Fig. 8E View Fig 1–E View Fig 2 View Fig ) preserves four molariforms (P3–M2) in addition to two isolated right P3 or P4, and M1 or M3, likely from the same individual. Occlusal length in the maxillary molariforms ranges approximately between 32 and 33 mm in premolars, and between 30 and 31 mm in molars. Te premolars exhibit fossettes and a prominent sub-elliptical protocone ( Fig. 8E View Fig 1 View Fig ). Te other isolated upper premolars and molars (PIMUZ A/V 4115, 4198, 4222, 4238–39; see Fig. 8D View Fig 1–D View Fig 2 View Fig , H 1–H View Fig 2 View Fig ) are robust and characterized by oval/elliptical to rounded protocone. Tese molariforms have occlusal length ranging approximately between 27 and 45 mm. Te isolated lower premolars/molars (PIMUZ A/V 4197, 4219, 4220, 4240; Fig. 8F View Fig 1–G View Fig 2 View Fig ) are characterized by a rounded and small metaconid and metastylid, and a rounded protoconid and hypoconid, a typical dental pattern of Hippidion ( Alberdi & Frassinetti, 2000; Alberdi & Prado, 2004; Alberdi et al., 2001b, 2003, 2005, 2006, 2007; Cerdeño et al., 2008; MacFadden, 1997; Prado et al., 2012, 2013; Scherer & Da Rosa, 2003). Tese occlusal length of the lower isolated molariforms range approximately between 30 and 37 mm. Te first phalanx of the third digit (PIMUZ A/V 4205, Fig. 8C View Fig 1–C View Fig 3 View Fig ) is not in a good state of preservation, and it is 80 mm in maximum length and a 64 mm in width.

Remarks

Te molariforms MHNG GEPI V-3779 exhibit fossettes and a prominent sub-elliptical protocone that differs from the oval to rounded protocone present in the molariforms of PIMUZ A/V 4100 assigned here to Hippidion cf. H. principale (see Fig. 8A View Fig 3 View Fig ). We cannot rule out that molariforms MHNG GEPI V-3779 from the Pampean region could belong to either H. principale or H. devillei . Hippidion saldiasi is smaller in size and to date is restricted to the Late Pleistocene of the Patagonian region and some localities in Chile ( Labarca et al., 2021; Prado & Alberdi, 2017). Our comparisons do not allow to offer a more precise determination of these specimens because their fragmentary nature and advanced tooth wear (e.g., PIMUZ A/V 4115, 4198, 4219-20, 4222, 4238- 40). In reference to the left first phalange PIMUZ A/V 4205, its broad shape suggests an attribution to Hippidion sp. (see Alberdi et al., 2001a).