Meeting Abstract
The skin of cingulates is imbedded with plates of boney osteoderms, sutured together into shields to protect 3 separate areas; the head, body, and tail. Osteoderms vary greatly in shape, number, and arrangement across cingulates. Shields typically disarticulate shortly after death and isolated osteoderms are more commonly recovered from the fossil record. Osteoderms comprising the cranial shield are thinner, more irregular in shape, and poorly sutured together compared to other regions; diminishing preservation potential. Among the extinct group of giant armadillos known as pampatheres, isolated cranial osteoderms are mentioned in the literature, but no complete cranial shield has been described. The Florida Museum houses 9 partial to nearly complete cranial shields of the pampathere, Holmesina floridanus and 2 of the larger and younger Holmesina septentrionalis. A complete Holmesina cranial shield is composed of ~75 osteoderms, and is only slightly longer than wide, bilaterally symmetrical, and widest at post-orbital protuberances, which curve ventrally. Osteoderm shape, number of sides, and thickness varies across the cranial shield, dependent on anatomical position. Compared to extant armadillos, the shield is most similar to that of the euphractines in osteoderm count and shield shape, and differs most from that of Dasypus, which exhibit a greater number of osteoderms and narrower shield with a pointed posterior periphery. Great diversity exists in the cranial shield of extinct glyptodonts. They differ from those of Holmesina in exhibiting fewer, larger, thicker, and ornate osteoderms comprising broader cranial shields with less pronounced post-orbital protuberances.
