Evaluating migration hypotheses for the extinct Glyptotherium using ecological niche modeling

The formation of the Isthmus of Panama allowed for migrations between the once separated continents of North and South America. This led to one of the greatest documented interchanges of biota in Earth history, wherein an array of species across many groups migrated between the continents. Glyptotherium, a giant extinct armadillo-like grazer, is an example of a taxon that likely originated in South America and migrated to North America. Here we use Ecological niche modeling to test the extent of suitable conditions for Glyptotherium in Central America and surrounding regions during the intervals when the taxon is thought to have dispersed, allowing for assessment of plausible migration routes and the hypothesis that the genus migrated from North America back to South America during the Rancholabrean (14 000–240 000 years ago). Our niche modeling results show suitable abiotic conditions for Glyptotherium in Central America and the surrounding area throughout the Plio-Pleistocene, with western South America (the ‘high road') suggested as their ancestors' route northwards. Depending on the extent of suitable conditions, it may have been possible for Glyptotherium to return to South America during the Rancholabrean. The results support previous hypotheses that the range of Glyptotherium was constrained by the need for warm, wet environments.