 Like other aquatic mammals, "Metamynodon" had small neural spines projecting upwards from the thoracic vertebrae, indicating weak neck muscles, which probably was due to buoyancy and a lack of necessity to support the head while submerged.The ribcage was broad and "Metamynodon" had a barrel-like chest similar to the hippo, which could either be an adaptation to an expanding digestive tract or to develop muscles necessary to prevent rolling over in the water.Like other aquatic mammals, the leg muscles–popliteus in the knee; gastrocnemius, soleus, and peroneus tertius in the calf; and extensor digitorum longus in the foot–were all large and well-developed, probably to exert more force while walking and to better wade through muddy soil.