 Both belonged to the Hesperornithes, a group of prehistoric birds which were uniquely adapted to diving and swimming, and had teeth.Otherwise, they were fairly similar to living birds rather than to more dinosaur-like forms such as "Archaeopteryx" or the Enantiornithes.As "Baptornis" was quite peculiar among the Hesperornithes, the family Baptornithidae has been established for it.