Interatheriinae, Ameghino, 1897

Pino, Santiago Hernández Del, Seoane, Federico D. & Cerdeño, Esperanza, 2022, New craniodental material of the typotherian notoungulates from the upper Oligocene of Mendoza, central-western Argentina and their taxonomical importance, Acta Palaeontologica Polonica 67 (4), pp. 983-997 : 995

Interatheriinae indet.

Fig. 5L .

Material.—MCNAM-PV 4724, isolated right upper molar (M2 or M3) from Mendoza Province, Argentina, upper Oligocene, Deseadan SALMA.

Description.—MCNAM-PV 4724 is a little worn cheek tooth of a juvenile or young adult individual. It is long and narrow, with labially extended parastyle ( Fig. 5L 1 ); it has an anterolabial fossette and a posterolingual groove on the lingual edge of the metaloph, but this groove disappears toward the base. Looking at the opposite end ( Fig. 5L 2 ), the outline changes, with an open-Y-shaped median valley, the metaloph lingually shorter, and the parastyle greatly curved posterolabially, separated from the paracone fold by a marked groove. The direction of the parastyle on the occlusal face resembles that of a M2 of Argyrohyrax proavus (e.g., Vera et al. 2017: fig. 2a, 3b), but more extended labially; in addition, the marked groove and the direction of the parastyle at the opposite end do not correspond to this species, as far as it can be observed in its holotype ( Vera et al. 2017: fig. 3b). A second interatheriine was recognized at Quebrada Fiera as Progaleopithecus sp. ( Vera et al. 2017: fig. 6r), based on lower teeth. The upper teeth of Progaleopithecus sp. are closer to MCNAM-PV 4724 in the labial projection of the parastyle, in both premolars and molars, as in Progaleopithecus tournoueri Ameghino, 1904 ( Vera et al. 2017: fig. 7k, l), but these teeth differ in the absence of a median lobe and the greater projection of the paracone fold. Instead, MCNAM-PV 4724 appears closer to the interatheriines from Salla, Bolivia ( Hitz et al. 2008). Both Brucemacfaddenia boliviensis Hitz, Billet, and Derryberry, 2008 , and Federicoanaya sallaensis Hitz, Billet, and Derryberry, 2008 , present upper cheek teeth with a median lobe and a labially extended parastyle in molars; B. boliviensis also has a greatly extended parastyle in premolars, an anterolabial fossette in little worn molars, and its size is closer to MCNAM-PV 4724 ( F. sallaensis is a smaller species). Due to the lack of a total similarity, we determine MCNAM-PV 4724 as Interatheriinae indet., but keeping in mind its possible relationship with B. boliviensis . On the other hand, this specimen is not comparable with the other undetermined interatheriid from Quebrada Fiera described by Vera et al. (2017: 622), because the latter (MCNAM-PV 4742) is a mandibular fragment with p4–m1.

Figures

Fig. 5. Dental remains (anterior to the left, except for D) of interatheriid notoungulates from Quebrada Fiera, Mendoza, Argentina; upper Oligocene, Deseadan SALMA. A–K. Argyrohyrax proavus Ameghino 1897. A. MCNAM-PV 4962, right maxillary fragment with DP1–DP4–M1, occlusal view reversed). B. MCNAM-PV 4961, maxillary fragments with left C–M2 in occlusal view (B1), see erupting C in SOM 1: fig. S5A, B and right P2–M2 in occlusal view (B2). C. MCNAM-PV 4986, left maxillary fragment with M1–M2 in occlusal view. D. MCNAM-PV 4245, mandibular symphysis with broken teeth in rostral view. E. MCNAM-PV 4646, right mandibular fragment with broken dp1–p2–p3 in occlusal view. F. MCNAM-PV 5082, right mandibular fragment with p2–m1 in occlusal view. G. MCNAM-PV 4963, right mandibular fragment with dp3–p4–m2 and separated m3 in occlusal G1, G2) and lingual (G3, G4) views. H. MCNAM-PV 4308, right lower molar (unerupted m3?) in occlusal view. I. MCNAM-PV 4622, left m3 (reversed) in occlusal view. J. MCNAM-PV 4623, right m3 in occlusal view. K. MCNAM-PV 5081, left m1 or m2 (reversed) in occlusal view. L. Interatheriidae indet. MCNAM-PV 4724, right upper molar in occlusal (reversed) (L1) and opposite (L2) views.

Fig. 1. Hegetotheriid notoungulate “Prohegetotherium schiaffinoi (Kraglievich, 1932)” from Quebrada Fiera, Mendoza, Argentina; upper Oligocene, Deseadan SALMA. MCNAM-PV 5076, skull in ventral (A1, A2), dorsal (A3, A4), left lateral (A5, A6), and occipital (A7, A8) views. White and gray areas indicate well-preserved bone or teeth and broken bone or teeth respectively; black areas indicates foramina, sulci and other natural depresions while striped areas indicate matrix. Photographs (A1, A3, A5, A7) and explanatory drawings (A2, A4, A6, A8).

Fig. 2. Upper dentition (anterior to the left) of hegetotheriid notoungulates from Quebrada Fiera, Mendoza, Argentina; upper Oligocene, Deseadan SALMA. A, B. “Prohegetotherium schiaffinoi (Kraglievich, 1932)”. A. MCNAM-PV 5076, left P1–M3 in occlusal view.B. MCNAM-PV 5086, right maxillary fragment with P4–M1 (reversed),in occlusal (B1) and labial (B2) views. C. “Prohegetotherium cf. P. schiaffinoi”, MCNAM-PV 4982, right maxillary fragment with M1–M3 (reversed) in occlusal (C1) and labial (C2) views. D, E. Hegetotheriinae indet. D. MCNAM-PV 4185, left M1 or M2 in occlusal view. E. MCNAM-PV 4612, left P4 or M1 in occlusal view. F, G. Prosotherium garzoni Ameghino, 1897. F. MCNAM-PV 4991, right maxillary fragment with M1–M2 (reversed) in occlusal view. G. MCNAM-PV 5016, right maxillary fragment with P2–M1 (reversed) in occlusal view.