Neobalaenidae is a family of baleen whales including the extant pygmy right whale. Although traditionally considered related to balaenids, recent studies by Fordyce and Marx (2013) and Ludovic Dutoit and colleagues (2023) have recovered the living pygmy right whale as a member of Cetotheriidae, making it the only extant cetotheriid. Not all authors agree with this placement.
Cetotherium is an extinct genus of baleen whales from the family Cetotheriidae.
Aetiocetus is a genus of extinct basal mysticete, or baleen whale that lived 33.9 to 23.03 million years ago, in the Oligocene in the North Pacific ocean, around Japan, Mexico, and Oregon, U.S. It was first described by Douglas Emlong in 1966 and currently contains known four species, A. cotylalveus, A. polydentatus, A. tomitai, and A. weltoni. These whales are remarkable for their retention of teeth and presence of nutrient foramina, indicating that they possessed baleen. Thus, Aetiocetus represents the transition from teeth to baleen in Oligocene mysticetes. Baleen is a highly derived character, or synapomorphy, of mysticetes, and is a keratinous structure that grows from the palate, or roof of the mouth, of the whale. The presence of baleen is inferred from the fossil record in the skull of Aetiocetus. Aetiocetus is known from both sides of the Pacific Ocean: it was first documented in Oregon, United States, but it is also known from Japan and Mexico. The genus is currently constrained to the Northern hemisphere and has little value in biostratigraphic studies of the Oligocene due to its limited occurrences across the Pacific.
Cetotheriidae is a family of baleen whales. The family is known to have existed from the Late Oligocene to the Early Pleistocene before going extinct. Although some phylogenetic studies conducted by Fordyce & Marx 2013 recovered the living pygmy right whale as a member of Cetotheriidae, making the pygmy right whale the only living cetotheriid, other authors either dispute this placement or recover Neobalaenidae as a sister group to Cetotheriidae.
Mesocetus is an extinct genus of baleen whale from the Miocene of Europe and North America.
Herpetocetus is a genus of cetotheriid mysticete in the subfamily Herpetocetinae. Considerably smaller than modern baleen whales, Herpetocetus measured only 3 to 4 meters in length. Additionally, due to the structure of its jaw, it was unable to open its mouth as wide as modern baleen whales, making it incapable of lunge feeding.
Aglaocetus is a genus of extinct baleen whales known from the Miocene of Patagonia, the US Eastern Seaboard, Japan and the Low Countries. It was once considered a member of Cetotheriidae along with many other putative cetotheres, but was recently recognized as representing a distinct family from true Cetotheriidae.
"Balaenoptera" ryani is an extinct species of Balaenopteridae from the late Miocene of California. It was originally considered a species of Balaenoptera, but is now recognized as more primitive than any extant or fossil balaenopterid and thus in need of a new generic name.
Mixocetus is a genus of extinct baleen whale belonging to the family Tranatocetidae. It is known only from the late Miocene (Tortonian) of Los Angeles County, California.
Nannocetus is an extinct baleen whale belonging to the family Cetotheriidae.
Metopocetus is an extinct genus of baleen whale belonging to the family Cetotheriidae. The type species is Metopocetus durinasus.
Otekaikea is an extinct genus of toothed whale closely related to Waipatia. It is known from the late Oligocene (Chattian) of New Zealand.
Eomysticetidae is a family of extinct mysticetes belonging to Chaeomysticeti. It is one of two families in the basal chaeomysticete clade Eomysticetoidea.
Brandtocetus is a genus of cetotheriid mysticete in the subfamily Cetotheriinae. The type and only species is Brandtocetus chongulek from the late Miocene (Tortonian) of the Kerch Peninsula in Crimea.
Zarhinocetus is an extinct genus of whale from the Early to Middle Miocene of the eastern North Pacific.
Waharoa is a genus of eomysticetid baleen whale from the Late Oligocene (Chattian) of New Zealand. It was identified with the discovery of Waharoa ruwhenua by Boessenecker and Fordyce (2015), which added a new genus and species to a monophyletic family Eomysticetidae.
Herentalia is a genus of cetotheriid mysticete in the subfamily Herpetocetinae. Remains have been found in Late Miocene marine deposits in Belgium.
Otradnocetus is an extinct genus of baleen whale from the middle Miocene of the Russian Caucasus.
Ciuciulea is a genus of cetotheriid mysticete found in middle Miocene marine deposits in Moldova.
Taikicetus is a genus of basal thalassothere baleen whale from the Middle Miocene of Japan.
