Taxonomy, paleoecology and taphonomy of ground sloths (Xenarthra) from the Fairmead Landfill locality (Pleistocene: Irvingtonian) of Madera County, California

Abstract

The Fairmead Landfill locality contains a diverse middle Irvingtonian, (0.78–0.55 Ma), vertebrate fauna that includes three sloths, Megalonyx wheatleyi, Nothrotheriops shastensis and Paramylodon harlani. The co-occurrence of these three genera in a single fauna is relatively rare in both the Irvingtonian and Rancholabrean and this is only the fourth documented Irvingtonian fauna to contain all three sloth genera. The presence of the three different sloths, each of which had different ecological requirements, indicates the presence of a variety of different habitats at this time and a heterogeneous landscape. Preliminary analysis of pollen from the site supports the interpretation of the existence of a mosaic of plant communities, but a landscape dominated by a mesic grassland. This interpretation is also supported by the total faunal diversity that includes taxa associated with woodlands as well as open habitat and taphonomic differences in the preservation and relative abundance of the different sloths. Evolutionarily the Fairmead Landfill sloths show a suite of morphological, size and proportional characters that indicate they represent transitional populations between older and younger members of their respective lineages.

Co-occurrence of mylodontid sloths and insights on their potential distributions during the late Pleistocene

“…Patagonia today (Politis and Messineo, 2008;Czerwonogora et al, 2011;Prevosti and Martin, 2013). McDonald et al (2013) studied the sloths co-occurrence records for the Fairmead Landfill locality (Irvingtonian) in North America to address the presence of different habitats in the region based on the different ecological requirements of the recorded sloths. This hypothesis was in accordance with supplementary pollen and faunal diversity studies at the site.…”