FOSSIL EVIDENCE OF GLYPTOTHERIUM CF. G. FLORIDANUM IN THE PLEISTOCENE OF LOUISIANA

At least one large glyptodont species is now identifiable from the Pleistocene of Louisiana, a pair of individual scutes and a partial rib. Each scute is somewhat hexagonal in shape, and the larger is nearly 7 centimeters across. The rib shows a well-preserved proximal end, and the cross-section at the broken distal end is square. The curvature of the rib suggests that roughly two-thirds of the rib is present before the break.

Much larger than their closest living relatives, armadillos, glyptodonts were primarily South American animals which migrated into North America through the Isthmus of Panama during the Great American Interchange. In the Gulf of Mexico region, glyptodonts were known from fossils in Texas, Florida, Mexico, and South Carolina. Two species, Glyptotherium arizonae and Glyptotherium floridanum, seem to be descended from a smaller, ancestral species, Glyptotherium texanum.

The Louisiana fossils, were recovered in float in a creek in the Tunica Hills, an area which has yielded many fossils considered to be Pleistocene in age as well as some as old as the Late Miocene. The glyptodont fossils appear to be most similar to G. floridanum, which is known from Florida and east Texas, but there were no known geographic barriers to prevent the species from dispersing to the states in-between, such as Louisiana. Some researchers consider glyptodonts to be semi-aquatic browsers, analogous in behavior to the capybara. Others have pointed out that South American glyptodonts often lived in habitats more indicative of drier climates than swampy lowlands. Unfortunately, the limited number of specimens along with the ambiguity of providence makes it unlikely that our fossils will add anything of value to the debate.

It is clear that glyptodonts were relatively rare in the Tunica Hills, as over 7,000 specimens from the region include only 3 glyptodont specimens. Rare earth element studies offer the possibility of associating the glyptodont material more definitively with a single population of float specimens from the creeks.