Colbertia lumbrerense Bond, 1981

Fernández, Mercedes, Zimicz, Ana N., Bond, Mariano, Chornogubsky, Laura, Arnal, Michelle, Cárdenas, Magalí & Fernicola, Juan C., 2021, New Eocene South American native ungulates from the Quebrada de los Colorados Formation at Los Cardones National Park, Argentina, Acta Palaeontologica Polonica 66 (1), pp. 85-97 : 89-90

Colbertia lumbrerense Bond, 1981

Fig. 2A, B.

Holotype: PVL 4607 , incomplete skull with right C, P1 – P4 , and left M1 – M3 ; and mandible with left i2–m3, and right p2–m3.

Type locality: Estancia Pampa Grande, Salta Province, Argentina.

Type horizon: Lower sections of the Lumbrera Formation, middle Eocene.

Material.—IBIGEO-P 45 ( Fig. 2A), right maxillary fragment with P4 and M3 from the same individual (both teeth were erroneously glued together, but due to their state of preservation they cannot be separated without breaking the material); and IBIGEO-P 56 ( Fig. 2B), broken right M1 or M2. Quebrada Grande, Los Cardones National Park, Casamayoran SALMA, Eocene.

Description.—IBIGEO-P 45 and IBIGEO-P 56 were not found associated; nevertheless, according to their similar structures and size, both are considered here as belonging to the same species. IBIGEO-P 45 presents poorly preserved P4 and M3; both teeth are brachydont and subquadrangular in outline. Unfortunately, not much can be mentioned from the former tooth since only its labial portion, including a broken ectoloph, is preserved. The M3 is less worn than the P4, and preserves its lingual portion; the protoloph is well developed and runs disto-lingually; there is a low mesial cingulum, which is lingually interrupted, whereas the distal cingulum continues more lingually; a reduced hypocone is identified in the metaloph. IBIGEO-P 56 is a low-crowned M1 or M2, subquadrangular in outline; it is also broken and lacks its ectoloph, but it is little worn and the remaining structures are well preserved; the mesio-lingual cingulum is located lower on the crown and well developed, and it is lingually interrupted; there is a reduced, but continuous lingual cingulum that surrounds the lingual region of the protoloph; both protoloph and metaloph are well developed, but the former is wider and more oblique than the latter; the protoloph is curved and runs disto-lingually, whereas the metaloph runs mesio-lingually; the lingual end of the metaloph (hypocone region) unites with the lingual end of the protoloph (protocone region), isolating a central fossette; the central fossette is narrow and oblique, disto-lingually directed; a vestigial lingual sulcus persists to the connection of the protoloph and metaloph; the crochet is short and runs mesio-labially from the metaloph to the ectoloph, isolating the disto-labial fossete, which is shallow in this specimen; the disto-lingual cingulum is higher than the mesio-lingual cingulum, and it is also lingually interrupted. All of these characteristics plus their size (see Table 1 ) allow us to identify IBIGEO-P 45 and IBIGEO-P 56 as Colbertia lumbrerense .

Remarks.— Colbertia lumbrerense was previously known only for the lower Lumbrera Fm. at Pampa Grande, Salta Bond 1981). In addition, Colbertia sp. has also been recognized in Geste Fm., Antofagasta de la Sierra ( López 1997), and in the early Eocene of Brazil (Itaboraian SALMA; Paula Couto 1952).

Fig. 2. New fossil specimens of Typotheria from the Quebrada de Los Colorados Fm. exposed at Quebrada Grande locality, Los Cardones National Park (Salta Province), Casamayoran SALMA, Eocene. A, B. Colbertia lumbrerense Bond, 1981 . A. IBIGEO-P 45, right maxillary fragment with P4 and M 3 in occlusal view. B. IBIGEO-P 56 , broken right M1 or M 2 in occlusal view. C–F. Colbertia falui sp. nov. C. IBIGEO-P 67 , left mandibular fragment with m2–m3 (holotype) in occlusal ( C 1 ), labial ( C 3 ), and lingual ( C 4 ) views. D . IBIGEO-P 55 , right mandibular fragment with p3–p 4 in occlusal view. E. IBIGEO-P 59 , left mandibular fragment with m2–m 3 in occlusal view. F. IBIGEO-P 61 , left mandibular fragment with m1 (talonid)–m 3 in occlusal view. Photographs ( A 1 , B 1 , C 1 , C 3 , C 4 , D 1, E 1 , F 1 ), explanatory drawings ( A 2 – F 2 ). Dashed area indicates broken or missing dental areas .

Stratigraphic and geographic range.—Upper section of the Lumbrera and Quebrada de Los Colorados formations, middle Eocene; Salta Province, Argentina.