Marine Mammal Protection Act Indian manatee, sea otter, polar bear, and Pacific walrus. Species not present in U.S. waters include the West African and Amazonian manatee, dugong, Atlantic walrus, and marine otter. In efforts to conserve and manage marine mammal species, the Service has appointed field staff dedicated to working with partners to conduct population censuses, assess population health, develop and implement conservation plans, promulgate regulations, and create cooperative relationships internationally. Various Marine Mammal Management offices are located on either coast. The Service's Marine Mammal Management office in Anchorage, Alaska is responsible for the management and conservation of polar bears, Pacific walruses, and northern
Mammal the early [[Permian]]. Nonmammalian synapsids are sometimes called "mammal-like reptiles". [[Therapsid]]s, a group of synapsids, descended from [[pelycosaur]]s in the Middle Permian, about 265 million years ago, and became the dominant land vertebrates. They differ from basal [[Eupelycosauria|eupelycosaurs]] in several features of the skull and jaws, including: larger skulls and [[incisor]]s which are equal in size in therapsids, but not for eupelycosaurs. The therapsid lineage leading to mammals went through a series of stages, beginning with animals that were very similar to their pelycosaur ancestors and ending with [[probainognathia]]n [[cynodont]]s, some of which could easily be mistaken for mammals. Those