Dasypodinae, Gray, 1821

Ciancio, Martín R., Herrera, Claudia, Aramayo, Alejandro, Payrola, Patricio & Babot, Judith, 2016, Diversity of cingulate xenarthrans in the middle-late Eocene of Northwestern Argentina, Acta Palaeontologica Polonica 61 (3), pp. 575-590 : 581

Dasypodinae gen. et sp. indet.

Fig. 4G .

Material.— MLP 88 -V-10-19, posterior portion of a movable osteoderm from Antofagasta de la Sierra, Catamarca Province, Argentina; middle member of the Geste Formation (sensu Alonso 1992); middle–late Eocene .

Description.—This broken osteoderm has some peculiar features that indicate that it could represent a new taxon. The osteoderm is larger than those of the others Dasypodinae from Geste levels, and similar in size to the extant species Dasypus kappleri . The main figure is lageniform, with a long neck that widens and reaches the lateral edges on the posterior third of the osteoderm. The morphology of the main figure is an intermediate condition between Stegosimpsonia ( Astegotheriini ; Fig. 4H ) and Anadasypus ( Dasypodini ; Fig. 4J ). In the former, the main figure opens on the middle portion of the osteoderm (see Vizcaíno 1994: fig. 2), and in Anadasypus this occurs more posteriorly (see Carlini et al. 2013: fig. 4). Both sides of the main figure are bounded by lateral figures. There are many foramina (10 or more) on the external surface that open in the sulci delimiting the main figure, and continue on the posterolateral margins. The posterior margin lacks foramina. Stegosimpsonia has up to 20 foramina surrounding the entire main figure, including the posterior border ( Vizcaíno 1994; Carlini et al. 2010). Anadasypus has fewer foramina (9) but they are absent at the posterior edge (Carlini et al. 2014; Fig. 4H–J ).

Measurements.—> 14 mm long (anterior portion is broken; the total length could be around 25 mm), 7.5 mm wide, and 3 mm thick.

Remarks.—The material shares morphological characteristics with astegotheriins and Anadasypus , a primitive Dasypodini (see Carlini et al. 2013; Castro et al. 2014); hence, it could be considered as a primitive Dasypodini or a derived Astegotheriini . Previously, Babot et al. (2012) described an isolated petrosal bone of a Dasypodinae from Geste Formation at Antofagasta de la Sierra, which has a morphology more similar to Dasypus ( Dasypodini ) than to other Dasypodinae . However, taking into account the temporal range of Geste formation, and the lack of cranial remains of Astegotheriini to compare, it is difficult a more accurate assignation. The presence of a Dasypodini in Geste Formation might indicate an earlier origin of the group, up to 25 Ma earlier than it is known. Unfortunately, the few remains of this taxon prevent us to adjust the determination and clarify these speculations; probably, best preserved remains could provide new evidence in this regard.

Figures

Fig. 4. Dasypodines from the middle member of the Geste Formation, middle–late Eocene, Northwestern Argentina.A. cf. Astegotherium sp., fixed osteoderm, MHAS 067; Quebrada El Paso, near the Pozuelos salt flat, Los Andes Department, Salta Province. B, C.?Prostegotherium sp., movable osteoderms, MHAS 024 (B) and PVL 6567 (C); Antofagasta de la Sierra, Catamarca Province. D−F. Parastegosimpsonia cf. P. peruana, fixed osteoderms, PVL 6569 (D) and MLP 88-V-10-19A (E, broken); movable osteoderm, PVL 6409 (F); Antofagasta de la Sierra, Catamarca Province. G. Dasypodinae indet., movable osteoderm, MLP 88-V-10-19; Antofagasta de la Sierra, Catamarca Province. H−J. Movable osteoderms of Stegosimpsonia (H), Dasypodinae indet. (I) and Anadasypus (J). Photographs (A1−G1), line drawings (A2−G2, H−J). H–J, not to scale.