Miophocaena
Miophocaena nishinoi is an extinct species of porpoise from the Late Miocene Koetoi Formation of Japan, dating to around 6.4–5.5 million years ago (mya), represented by a partial skull. the genus name derives from Ancient Greek "mio" for the Miocene, and "phocaena" for "porpoise"; the species name honors the discoverer, Takanobu Nishino. "Miophocaena" resides in a clade with "Archaeophocaena" discovered in the same area, and, along with "Pterophocaena", represents an intermediate phase between porpoises and dolphins.