The earliest-known mammaliaform fossil from Greenland sheds light on origin of mammals

Mammals underwent an adaptive radiation shortly after the acquisition of several morphological characters in their dentition and jaw. Most of these innovations evolved to facilitate more efficient food processing. The double-rooted molariforms with a specialized crown are one such innovation, but their role in the early diversification of mammals has remained poorly understood. This study shows a comprehensive analysis of an early mammaliaform dentary, which combines data from comparative anatomy, CT scanning, and FEA. The new fossil fills an important gap in our understanding of mammaliaform evolution showing a transitional stage between triconodont-like molariform pattern of morganucodontids and multicusped pattern of haramiyidans. Moreover, this study demonstrates that double-rooted teeth are more resistant to bite-related stresses than single-rooted teeth.