Cover image:
Comparison of the humerus distal end of two bears: a fossil Agriotherium and a recent Ursus Maritimus. On left, Agriotherium (MPGJ 5676) from Juchipila basin, Zacatecas Mexico, early-late Hemphillian age; the medial epicondyle is convex, the external epicondylar ridge has a thick rim with two deep grooves in the middle. On right, Ursus maritimus with a long hook-shaped medial condyle important in retaining prey for feeding. The lateral epicondylar ridge is concave deep throughout its length. See the related paper by Carranza-Castañeda and Wang in this issue.