Dugongidae is a family in the order of Sirenia. The family has one surviving species, the dugong, one recently extinct species, Steller's sea cow, and a number of extinct genera known from fossil records.
Plotopteridae is an extinct family of flightless seabirds with uncertain placement, generally considered as member of order Suliformes. They exhibited remarkable convergent evolution with the penguins, particularly with the now extinct giant penguins. That they lived in the North Pacific, the other side of the world from the penguins, has led to them being described at times as the Northern Hemisphere's penguins, though they were not closely related. More recent studies have shown, however, that the shoulder-girdle, forelimb and sternum of plotopterids differ significantly from those of penguins, so comparisons in terms of function may not be entirely accurate. Plotopterids are regarded as closely related to Anhingidae (darters) and Phalacrocoracidae (cormorants). On the other hand, there is a theory that this group may have a common ancestor with penguins due to the similarity of forelimb and brain morphology. However, the endocast morphology of stem group Sphenisciformes differs from both Plotopteridae and modern penguins.
Archaeoceti, or Zeuglodontes in older literature, is a paraphyletic group of primitive cetaceans that lived from the Early Eocene to the late Oligocene. Representing the earliest cetacean radiation, they include the initial amphibious stages in cetacean evolution, thus are the ancestors of both modern cetacean suborders, Mysticeti and Odontoceti. This initial diversification occurred in the shallow waters that separated India and Asia 53 to 45 mya, resulting in some 30 species adapted to a fully oceanic life. Echolocation and filter-feeding evolved during a second radiation 36 to 35 mya.
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.
Kentriodontidae is an extinct family of odontocete whales related to modern dolphins. The Kentriodontidae lived from the Oligocene to the Pliocene before going extinct.
The Hoko River Formation is a Late Eocene marine sedimentary geologic formation. The formation is exposed in outcrops along the Strait of Juan de Fuca on the Olympic Peninsula in Washington state, USA. It is known for containing numerous fossils of crabs. It overlies the older Lyre Formation and underlies the younger Makah Formation.
Bohaskaia is an extinct genus of beluga-like odontocete cetacean known from the Early Pliocene of Virginia and North Carolina, United States. It was first named by Jorge Vélez-Juarbe and Nicholas D. Pyenson in 2012 and the type species is Bohaskaia monodontoides.
Xenorophidae is an extinct family of odontocetes currently known from the Oligocene of the southeastern US. Known genera of xenorophids include Albertocetus, Archaeodelphis, Cotylocara, Echovenator, Inermorostrum, and Xenorophus.
The Ashley Formation is a geologic formation in South Carolina. It preserves fossils dating back to the Paleogene period.
The Chandler Bridge Formation is a geologic formation in South Carolina. It preserves fossils dating back to the Chattian of the Paleogene period, corresponding to the Arikareean in the NALMA classification. The formation overlies the Ashley Formation and is overlain by the Edisto Formation.
Isthminia is a genus of medium-sized river dolphin cetaceans that lived during the Late Miocene epoch in what is now the coasts of Panama, about 6.1 million to 5.8 million years ago. The type species is I. panamensis, known from the littoral Chagres Formation.
Scaphokogia is an extinct genus of pygmy sperm whales that lived off the coasts of Mexico and Peru, South America during the Late Miocene to Late Pliocene. Two species have currently been described: the type species S. cochlearis and S. totajpe. Fossils of Scaphokogia have been found in the Tirabuzon Formation of Baja California and the Pisco Formation of Peru. Scaphokogia existed about 5 million years ago, and were relatively rare animals.
Squaloziphius is an extinct genus of odontocete cetacean from the Early Miocene (Aquitanian) aged marine deposits in Washington state.
Agorophius is an extinct genus of toothed whale that lived during the Oligocene period, approximately 32 million years ago, in the waters off what is now South Carolina.
Mirocetus is a genus of archaic odontocete from the late Oligocene (Chattian) of Azerbaijan. Like many other primitive odontocetes, its classification has been fluid since its description.
Xenorophus is a genus of primitive odontocete from late Oligocene (Chattian) marine deposits in South Carolina belonging to Xenorophidae.
Dioplotherium is an extinct genus of mammal known from Neogene deposits in the southeastern United States.
Tonsala is an extinct genus of Plotopteridae, a family of flightless seabird similar in biology with penguins, but more closely related to modern cormorants. The genus is known from terrains dated from the Late Oligocene of the State of Washington and Japan.
Klallamornis is an extinct genus of Plotopteridae, a family of large, flightless birds related to modern cormorants, darters, gannets, and boobies. This genus included the largest North American plotopterids. Its remains can be found in Late Eocene to Late Oligocene rocks from the Makah Formation, the overlying Pysht Formation and the Lincoln Creek Formation of the State of Washington. During its existence, Klallamornis was the largest plotopterid on the North American continent. The first fossil remains attributed to the taxon were collected in 1983, although the genus wasn't described until 2016.
