Colbertia falui, Fernández & Zimicz & Bond & Chornogubsky & Arnal & Cárdenas & Fernicola, 2021

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 : 90-92

Colbertia falui sp. nov.

Fig. 2C–F.

Etymology: In honor of Eduardo Falú (1923–2013), an Argentinian folk music composer and guitarist, strongly influenced by the folk traditions of Salta Province.

Holotype: IBIGEO-P 67 ( Fig. 2C), left mandibular fragment with m2– m3.

Type locality: Los Cardones National Park, Salta Province, Argentina.

Type horizon: Quebrada de Los Colorados Fm., Casamayoran SALMA, Eocene.

Material.—IBIGEO-P 55 ( Fig. 2D), right mandibular fragment with p3–p4; IBIGEO-P 59 ( Fig. 2E), left mandibular fragment with m2–m3; IBIGEO-P 61 ( Fig. 2F), left mandibular fragment with the talonid of m1, and m2–m3. Quebrada Grande, Los Cardones National Park, Casamayoran SALMA, Eocene.

Diagnosis.—Small notoungulate with brachydont dentition. Colbertia falui exhibits a similar size to the larger specimens of C. magellanica and C. lumbrerense . C. falui matches C. lumbrerense , and differs from C. magellanica , in the presence of a proportionally less elongated talonid of m3. C. falui differs from both C. magellanica and C. lumbrerense in the presence of lower cheek teeth with both more labially angular and oblique trigonid; lower premolars more labio-lingually compressed; with proportionally larger trigonid, and shorter talonid; ectoflexid transversally deeper; lower molars with more complex occlusal surfaces due to the presence of a more developed paralophid and more expanded metalophid and entoconid; the latter is located in a more mesial position, being closer to the region of the metaconid; deep talonid basin that is lingually narrower; disto-lingual sulcus transversally shallower; more developed cingulids; and the m3 with less lingually projected hypoconulid.

Description.—All the materials assigned to this species are well preserved. In IBIGEO-P 55, the p3 is longer than wide; the trigonid is subtriangular in outline, and slightly higher than the talonid; both protoconid and metaconid are well defined, the latter being slightly lower than the former; the protoconid is located in a more labial position than the paralophid and exhibits a mesial crest; the paralophid is low and lingually curved; the protoconid is connected to the metaconid by a short crest (= metalophid); the metaconid extends disto-lingually by a descendent crest; there is no trace of a paraconid; the talonid is short, subtriangular in outline, and lingually curved, and it is slightly narrower and markedly shorter than the trigonid; the cristid obliqua is connected to the disto-lingual region of the metalophid; the mesio-lingual sulcus of the trigonid is wide and opens lingually, whereas the disto-lingual sulcus in the talonid is short and narrow; the labial sulcus is deep and narrow; there are no traces of labial and lingual cingulids; a reduced mesio-lingual cingulid is identified. The p4 is larger and more molariform than the p3, but not completely molariform; it shows the same general features as described above for p3, but it is distinguished from it by the presence of a more developed talonid, which is also more lingually curved; the metaconid is higher than the protoconid and the paralophid; the entoconid is differentiated and lophoid, separated from the metaconid region; the hypoconulid is markedly reduced unidentified in p3), and connected to a distal cingulid that does not extend lingually. The m1 is only represented by a broken talonid (IBIGEO-P 61) that exhibits the same general characteristics as the m2, except that it is more subquadrangular in outline. In IBIGEO-P 59, 61, and 67, the trigonid of m2 is wider than long, and slightly higher than the talonid; the paralophid is well developed, and directs lingually; a lower mesio-lingual cingulid is connected to the lingual edge of the paralophid that will eventually merge with it with wear; the metalophid is mesio-distally expanded and there is a small extension in the mesial wall of the metaconid, which suggests a fused paraconid; the metaconid is the highest cuspid; the metalophid is well developed, almost straight and slightly disto-lingually directed; the cristid obliqua is connected to the middle portion of the metalophid; the labial sulcus is both transversally and longitudinally deep; the talonid is well developed, and it is wider and much larger than the trigonid, and subrectangular in outline; the talonid basin is wide and deep; the lophoid entoconid is well developed, and mesially and transversally expanded, connected to the hypoconid; the distal face of the entoconid is located mesio-lingually to the hypoconulid; the latter is separated from the former by a deep valley, which is limited by a low disto-lingual cingulid that connects the entoconid and the hypoconulid; the hypolophid is reduced and slightly lingually curved. The m3 is larger than the m2 and shows the same general features, but it can be distinguished from its predecessor by the following characteristics: presence of an enlarged talonid due to a larger and more lingually curved hypolophid; talonid slightly narrower than the trigonid; presence of a deeper distal valley; and more conspicuous disto-lingual cingulid that connects the hypoconulid and the disto-lingual wall of the entoconid; with wear, these structures merge and isolate a small fossettid as observed in IBIGEO-P 61, which is the most worn specimen assignable to C. falui .

→

Stratigraphic and geographic range.—Quebrada de Los Colorados Formation, middle Eocene; Salta Province, Argentina