 Unlike other ground sloths which put a lot of stress on their hind limbs for locomotion—specifically from standing on two legs (bipedalism)—the leg bones of "Thalassocnus" are slender.Bipedalism also led to shorter tibiae in ground sloths; the opposite is seen in "Thalassocnus" where the tibiae and femora are about the same length.The earlier species, like other sloths, bore their weight on the sides of their feet (pedolateral), whereas the later species planted their feet flat (plantigrade) to better paddle and walk along the seafloor.