| Squalodelphinidae | |
|---|---|
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Artiodactyla |
| Infraorder: | Cetacea |
| Superfamily: | Platanistoidea |
| Family: | † Squalodelphinidae Dal Piaz, 1917 |
| Genera | |
Squalodelphinidae is a family of primitive platanistoid river dolphins, found in marine deposits in the eastern Pacific, western Atlantic, and Europe. [1]
Distinguishing features of Squalodelphinidae include a moderately elongated and tapered rostrum, posterior cheek teeth being single-rooted but retaining accessory denticles, and marked skull asymmetry. Members of the family can be differentiated from the South Asian river dolphin by their shorter rostrum. [2]
River dolphins are a polyphyletic group of fully aquatic mammals that reside exclusively in freshwater or brackish water. They are an informal grouping of dolphins, which itself is a paraphyletic group within the infraorder Cetacea. Extant river dolphins are placed in two superfamilies, Platanistoidea and Inioidea. They comprise the families Platanistidae, the recently extinct Lipotidae, Iniidae and Pontoporiidae. There are five extant species of river dolphins. River dolphins, alongside other cetaceans, belong to the clade Artiodactyla, with even-toed ungulates, and their closest living relatives the hippopotamuses, from which they diverged about 40 million years ago. Specific types of dolphins can be pink.
South Asian river dolphins are toothed whales in the genus Platanista, which inhabit the waterways of the Indian subcontinent. They were historically considered to be one species with the Ganges river dolphin and the Indus river dolphin being subspecies. Genetic and morphological evidence led to their being described as separate species in 2021. The Ganges and Indus river dolphins are estimated to have diverged 550,000 years ago. They are the only living members of the family Platanistidae and the superfamily Platanistoidea. Fossils of ancient relatives date to the late Oligocene.
Iniidae is a family of river dolphins containing one living genus, Inia, and four extinct genera. The extant genus inhabits the river basins of South America, but the family formerly had a wider presence across the Atlantic Ocean.
Platanistidae is a family of river dolphins containing the extant Ganges river dolphin and Indus river dolphin but also extinct relatives from freshwater and marine deposits in the Neogene.
The Ganges river dolphin is a species of freshwater dolphin classified in the family Platanistidae. It lives in the Ganges and related rivers of South Asia, namely in the countries of India, Nepal, and Bangladesh. It is related to the much smaller Indus river dolphin which lives in the Indus River in Pakistan and the Beas River of northwestern India.
Squalodon is an extinct genus of whales of the Oligocene and Miocene epochs, belonging to the family Squalodontidae. Named by Jean-Pierre Sylvestre de Grateloup in 1840, it was originally believed to be an iguanodontid dinosaur but has since been reclassified. The name Squalodon comes from Squalus, a genus of shark. As a result, its name means "shark tooth". Its closest modern relative is the South Asian river dolphin.
Rostrum is a term used in anatomy for a number of phylogenetically unrelated structures in different groups of animals.
The blunt-snouted dolphin is a prehistoric pilot whale known from a single specimen, consisting of a partial rostrum, partial maxilla, partial premaxilla, and partial vomer. The fossil was discovered by Albert Hoekman on board a fishing trawler in the North Sea in 2008 and described in 2010 by Klaas Post and Erwin J.O. Kompanje. The blunt-snouted dolphin is believed to have had a balloonlike structure atop its rostrum and is estimated to have lived during the middle Pliocene to early Pleistocene.
The Indus river dolphin is a species of freshwater dolphin in the family Platanistidae. It is endemic to the Indus River basin in Pakistan and Beas River in northwestern India. This dolphin was the first discovered side-swimming cetacean. It is patchily distributed in five small, sub-populations that are separated by irrigation barrages.
Squalodontidae or the shark-toothed dolphins is an extinct family of large toothed whales who had long narrow jaws. Squalodontids are known from all continents except Antarctica, from the Oligocene to the Neogene, but they had a maximal diversity and global distribution during the Late Oligocene and Early to Middle Miocene.
Huaridelphis is an extinct genus of river dolphins from the Early Miocene. The type species is H. raimondii, found in the Chilcatay Formation of the Pisco Basin.
Septidelphis is an extinct genus of oceanic dolphins belonging to the family (Delphinidae). The type species is Septidelphis morii.
Zarhinocetus is an extinct genus of whale from the Early to Middle Miocene of the eastern North Pacific.
Allodelphinidae is a family of primitive platanistoid river dolphins found in marine deposits in the eastern North Pacific region, Alaska, and Japan.
Notocetus is an extinct genus of river dolphin belonging to Squalodelphinidae. Known specimens have been found in Early Miocene marine deposits from Argentina, Italy and Peru.
Arktocara is an extinct genus of river dolphin from the Oligocene epoch of Alaska, containing one species, A. yakataga. Having been discovered in 25-million-year-old strata near the 60th parallel north, it is perhaps the oldest-known crown toothed whale and the northmost river dolphin discovered. It was a member of the now-extinct family Allodelphinidae, along with the genera Allodelphis, Goedertius, Ninjadelphis, and Zarhinocetus. It measured approximately 2.26 or 2.28 meters, comparable to its closest living relative, the South Asian river dolphin, which measures 2.4 meters (7.9 ft). However, the animal probably had an elongated beak and neck, so it may have been longer. The animal is known only from a partially preserved skull. Its ecology may have been similar to the modern-day Dall's porpoise, and it may have competed with contemporaneous delphinoids. Its remains were found in the Poul Creek Formation, which has also yielded several mollusk species.
Goedertius is an extinct genus of river dolphin from the early Miocene (Burdigalian) Nye Formation of Oregon.
Phocageneus is an extinct genus of river dolphin belonging to Squalodelphinidae. Specimens have been found in the middle Miocene Calvert Formation of Maryland and Virginia.
Pomatodelphis is an extinct genus of river dolphin from Middle Miocene marine deposits in Alabama, Florida, Brazil, Germany and France.
Prepomatodelphis is an extinct genus of river dolphin from Early Miocene marine deposits in Austria.