Comparative anatomical investigations of the postcranial skeleton of Henkelotherium guimarotae Krebs, 1991 (Eupantotheria, Mammalia) and their implications for its locomotion

Abstract

The postcranial skeleton of the Late Jurassic Henkelotherium guimarotae exhibits a combination of primitive and modern characters, illuminating the early evolution of the therian “Grundplan”. Some of these characters (e.g., development of a supaspinous fossa) have been conserved in the later course of mammalian evolution, and have persisted to date with little variation in all therian taxa. Henkelotherium shares with certain small Recent mammals (Tupaiidae, Didelphidae) some primitive characters (e.g., asymmetric condyles of the femur), suggesting a mode of locomotion that is a similar to that in these living species. The small body size of Henkelotherium undoubtedly required some climbing abilities. This is supported by the paleoecological reconstruction of the Guimarota ecosystem indicating a densely vegetated environment. Henkelotherium shows features (e.g., elongated tail) that are interpreted here as adaptations for climbing. We suggest that Henkelotherium had a well developed capacity to move on discontinuous surfaces, displaying a flexible and versatile mode of locomotion.