 The orbits of remingtonocetids faced laterally and were small . This suggests that vision was not an important sense for them . The nasal opening , which eventually becomes the blowhole in modern cetaceans , was located near the tip of the snout . The position of the nasal opening had remained unchanged since pakicetids . One of the notable features in remingtonocetids is that the semicircular canals , which are important for balancing in land mammals , had decreased in size . This reduction in size had closely accompanied the cetacean radiation into marine environments . According to a 2002 study done by Spoor et al . , this modification of the semicircular canal system may represent a crucial ‘ point of no return ’ event in early cetacean evolution , which excluded a prolonged semi @-@ aquatic phase . 
