 Pakicetids have long thin legs , with relatively short hands and feet which suggest that they were poor swimmers . To compensate for that , their bones are unusually thick ( osteosclerotic ) , which is probably an adaptation to make the animal heavier to counteract the buoyancy of the water . According to a 2001 morphological analysis by Thewissen et al . , pakicetids display no aquatic skeletal adaptation ; instead they display adaptations for running and jumping . Hence pakicetids were most likely aquatic waders . 
