Diversity of cingulate xenarthrans in the middle-late Eocene of Northwestern Argentina
Ciancio, Martín R.
Herrera, Claudia
Aramayo, Alejandro
Payrola, Patricio
Babot, Judith
Acta Palaeontologica Polonica
2016
2016-02-29
61
3
575
590
cf. Astegotheriumsp. Fig. 4A. Material.—MHAS 067, fixed osteoderm from Quebrada El Paso, near the Pozuelos salt flat, Los Andes Department, Fig. 4. Dasypodines from the middle member of the Geste Formation, middle–late Eocene, Northwestern Argentina. A. cf. Astegotheriumsp., fixed osteoderm, MHAS 067; Quebrada El Paso, near the Pozuelos salt flat, Los Andes Department, Salta Province. B, C.? Prostegotheriumsp., movable osteoderms, MHAS 024 ( B) and PVL 6567 ( C); Antofagasta de la Sierra, Catamarca Province. D −F. Parastegosimpsoniacf. 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. Dasypodinaeindet., movable osteoderm, MLP 88-V-10-19; Antofagasta de la Sierra, Catamarca Province. H −J. Movable osteoderms of Stegosimpsonia( H), Dasypodinaeindet. ( I) and Anadasypus( J). Photographs (A 1 −G 1), line drawings (A 2 −G 2, H −J). H–J, not to scale. Salta Province, Argentina; middle member of the Geste Formation (sensu Alonso 1992); middle–late Eocene. Description.—This small osteoderm is similar in size to those of the living Dasypus hybridusor D. septencinctus. The osteoderm has a smooth surface and a lageniform principal figure with an elevated medial keel. There are an anterior and two anterolateral peripheral figures. The lateral border is smooth and slightly concave. On the posterior edge, there are two small piliferous foramina. Unlike other astegotheriins, Astegotheriumhave very few (or no) foramina surrounding the central figure. The differences of the osteoderm here described with those of the only species formally described for this genus, Astegotherium dichotomus, are the sulcus delimiting the principal and peripheral figures well defined, the posterior border straight (not bevel-shaped), the relative thickness, and the smaller size of the osteoderm. Measurements.— 6.8 mmlong, 5.8 mmwide, and 3 mmthick. Remarks.— Astegotheriumrepresents a taxon frequently recorded in Eocene beds of Patagonia. The only species formally described is Astegotherium dichotomusAmeghino, 1902from the early Casamayoran (Vacan subage of the Casamayoran SALMA, middle Eocene; Ciancio et al. 2013a, 2014), although a probably new species was mentioned from early–middle Eocene levels exposed at Laguna Fría ( Tejedor et al. 2009).