Pampatherium mexicanum Edmund, 1996

Tomas-Mosso, Azarael, Castañeda-Posadas, Carlos, Cruz, J. Alberto & Alarcón-Durán, Ivan, 2024, Pleistocene record of mammals and pollen from Mexico (Las Tazas, Valsequillo, Puebla) and their paleoenvironmental interpretation, Palaeontologia Electronica (a 15) 27 (1), pp. 1-18 : 4-5

Pampatherium mexicanum Edmund, 1996

Referred material. One movable osteoderm (dermal bony plate) ( BUAPAL 768; Figure 3A ), movable osteoderm fragment ( BUAPAL 767; Figure 3B ), and two fixed scapular shields ( BUAPAL 769 and 779; Figure 3C–D ).

Description. The complete movable osteoderm (BUAPAL 768) has a rectangular shape with three sections (Montellano-Ballesteros, 1991). The lower part (45 mm) has a series of shallow foramina in the lower margin. The middle part (30 mm) is rugose and has a 35 mm long curvature at the attachment near the upper part; this latter part is completely smooth (Montellano-Ballesteros, 1991; Aguilar and Laurito, 2009; Góis Lima, 2013).

The movable osteoderm fragment (BUAPAL 768) only has the upper part (25 mm), with a rectangular shape, reticulations on the anterior articular surface, and a series of dots on the sculpted surface, mainly on the contour of the surface. The fixed osteoderms (BUAPAL 769 and 779) from the scapular region have a poorly marked ornamentation composed of multiple small pores, its marginal elevation is flattened or diffuse, and the longitudinal depressions are superficial.

Comparison and remarks. The family Pampatheriidae is represented in Mexico by two genera, Pampatherium and Holmesina . This family is characterized by diagnostic osteoderms that allow the distinction between the two genera (Edmund, 1996; Scillato-Yané et al., 2005). Pampatherium mexicanum is the only recognized species of this genus in North America (Mead et al., 2007). Movable osteoderms in the genus Pampatherium are poorly ornamented, the marginal band may be absent, particularly in the Mexican population, or may consist of a narrow band of follicular pores on the posterior part and the lateral margins; the marginal band is not significantly depressed under the submarginal band and in the central part is broad, low, and without protrusions or a raised keel (Edmund, 1996), which are characteristics observed in the fossil material from Las Tazas.

Figures

FIGURE 3. Fossil material of pampathere and horses from Las Tazas, Valsequillo, Puebla. Pampatherium mexicanum: A, movable osteoderm (BUAPAL 768); B, movable osteoderm fragment (BUAPAL 767); C, fixed scapular shield (BUA- PAL 769); D, fixed scapular shield (BUAPAL 779). Equus conversidens: E, left M2 (BUAPAL 773); F, right M3 (BUAPAL 774). Equus sp.: G, right p3 (BUAPAL 771); H, right m2 (BUAPAL 772); I–J, left mandible (BUAPAL 780). Figures A–D in dorsal view; E–H and J in occlusal view; I in labial view.