Glyptodon reticulatus Owen, 1845

Glyptodon reticulatus Owen, 1845

Referred material: Incomplete tail in five pieces and 20 isolated osteoderms from the tail: PIMUZ A/ V 4122

( Fig. 9 View Fig ).

Comment: Specimen PIMUZ A/V 4122 from the Lujanian has a distal tip of the tail with thick osteoderms without a tip in contrast to the isolated osteoderms which all show a well-defined tip. Tese traits leave no doubt about the attribution to Glyptodon , but a more precise attribution is challenged by the close similarity of the tail between G. munizi and G. reticulatus (Cuadrelli et al., 2019, 2020). It is noteworthy that the distal tip of the tail does not present the robusticity known in G. jatunkhirkhi . According to Cuadrelli et al. (2019), the caudal armor of G. reticulatus is significantly smaller than the one of G. munizi , which is what I observe when I compare PIMUZ A/V 4122 with PIMUZ A/V 463, the latter being assigned to G. munizi . Because of this size difference, I favor an assignment of PIMUZ A/V 4122 to G. reticulatus , but it should be noted that this new assignment remains tenuous considering the reasons mentioned above. All so far described species of Glyptodon from the Pleistocene Pampean Region are represented in the PIMUZ collection; G. munizi is much more abundant than G. reticulatus . Te difference in abundance could be due to a sampling bias both temporally and spatially, but this difference could also reveal a biological reality arising from potential competitiveness among the many glyptodont species present at the end of the Ensenadan ( Fig. 2), or from environmental change induced by climate change occurring at the Bonaerian and the Lujanian (see below and Fig. 2), or a combination of these two factors.