The three cetacean suborders (two living, one fossil) recognized below s.... genera. speci

(whales, dolphins, and porpoises) 81 species in 2 suborders. ( and 32 species in 12 genera. About 35 fossil genera, Lower Miocene to Holocene. 21 species in 6 genera. Some neck vertebrae fused; functional teeth greatly reduced in number to 1 or 2 pairs in lower jaw (except for total 100 teeth in Tasmacetus ); vestigial (nonfunctional) teeth not uncommon. ( 6 species in 3 genera. Some neck vertebrae fused; well-defined beak absent; teeth with expanded spade-shaped crowns. Adult length in living species to about 2 metres. Virtually worldwide, marine, 1 species living in some rivers in China and Japan. 3 fossil genera. ( 5 species in 4 genera. ( 3 species in 2 genera. Some neck vertebrae fused; head disproportionately large, with bulbous, squared snout; mouth narrow and ventral; lower teeth total 4052 in Physeter , 1632 in Kogia ; upper teeth vestigial, smaller, varying in number. ( and 2 species in 2 genera. Teeth reduced to 8 or 10 in Delphinapterus (beluga); all teeth vestig! ial in Monodon (narwhal) except for 1 left tooth of male, which grows into a long, straight tusk extending in front of the animal. 3 genera. Families Eurhinodelphidae, Hemisyntrachelidae, and Acrodelphidae About 12 genera of Miocene toothed whales similar to today's dolphins. ( and 8 species in 2 genera. Upper Miocene to present. ( 1 species. ( 4 species in 2 genera. 4 fossil genera. 1 species. Skull slightly arched; neck vertebrae fused; lower jaw broad; baleen long and narrow; ventral grooves lacking; dorsal fin present; proximal portion of ribs extremely widened; lumbar vertebrae reduced to 2. 1 genus, possibly 2. 2 genera. 4 genera. Anterior and posterior teeth differentiated; total teeth not exceeding 44, the basic number in terrestrial placental mammals. 3 genera. 2 genera. 4 genera. genera. speci