Fig. 15
From: From Land to Water: the Origin of Whales, Dolphins, and Porpoises
The skeleton of A. natans (H-GSP 18507) had a large pelvis that supported the animal as it walked on land, but the tail and hind limbs were used during swimming (http://www.neoucom.edu/DEPTS/ANAT/publ.html, © J.G.M. Thewissen). The hammer provides a scale