{{Short description|Extinct family of mammals}} {{Automatic taxobox | fossil_range = {{Fossil range|Late Oligocene|Middle Miocene}} | image = Squalodon BW.jpg | image_upright = 1.15 | image_caption = ''Squalodon'' | taxon = Squalodontidae | authority = {{Harvnb|Brandt|1873}} | subdivision_ranks = Genera | subdivision_ref = <ref name="FW-42939">{{Cite web | title =†family Squalodontidae Brandt 1873 (toothed whale) |website= Fossilworks | url = https://paleobiodb.org/classic/checkTaxonInfo?taxon_no=42939 | access-date = 17 December 2021}}</ref> | subdivision = * ''Eosqualodon''<br /><small>Rothausen 1968</small> * ''Neosqualodon''<br /><small>Dal Piaz, 1904</small> * ''Squalodon''<br /><small>{{Harvnb|Grateloup|1840}}</small> * ?''Tangaroasaurus''<br /><small>Benham 1935</small> * ?''Phoberodon''<br /><small>Cabrera, 1926</small> }}
'''Squalodontidae''' or the '''shark-toothed dolphins''' is an extinct family of large toothed whales who had long narrow jaws.<ref name="Fordyce">{{Cite web | last = Fordyce | first = R Ewan | title = Shark-toothed dolphins (Family Squalodontidae) | date = June 2018 | publisher = University of Otago, Department of Geology | url = http://www.otago.ac.nz/geology/research/paleontology/squalodontidae.html}}</ref> 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 ({{Mya|28|15|mya}}).<ref name="Fordyce" /><ref name="FW-42939" />
With their cosmopolitan Miocene distribution and heterodont dentition, squalodontids are the most common and basal platanistoids. They are relatively large odontocetes, comparable in size to extant mesoplodont whales. The premaxillae on their elongated rostrum have large and slightly convex fossae for the air sacs associated with the presence of a melon, indicating the ability for echolocation.<ref name="Muizon-2008">{{Harvnb|Muizon|2008|p=980}}</ref>
''Squalodon'' and ''Eosqualodon'' are based on partial or complete skulls. The synapomorphic traits of the family are, however, based mostly on one of the bones of the inner ear, the periotic bone, which is unknown in these genera except in ''Squalodon''. The monophyly of the family is, therefore, uncertain. ''Patriocetus'' has also been included.<ref name="Muizon-2008" />
Some squalodontids are known from rather complete fossils, but most were described based on a few isolated teeth. Squalodontids are most likely very distantly related to extant oceanic dolphins but, according to French palaeontologist Christian de Muizon, more closely related to the South Asian river dolphin (''Platanista gangetica'').<ref name="Fordyce" />
The genus ''Squalodon'' was named by French naturalist Jean-Pierre Sylvestre de Grateloup in 1840<ref>{{Harvnb|Grateloup|1840}}</ref> based on a jaw fragment he thought belonged to a reptile. Fossils discovered later, nevertheless, showed that this was a toothed whale. In extant odontocetes, however, the dentition is atavistic with all teeth reduced to simple, undifferentiated conical shapes. In squalodonts the teeth resemble those of the archaic whales, Archaeoceti, with conical incisors anteriorly and low-crowned, serrated teeth posteriorly.<ref name="Fordyce" />
==References== ===Notes=== {{Reflist}}
===Sources=== {{Refbegin}} * {{Cite journal | last = Brandt | first = J. F. | author-link = Johann Friedrich von Brandt | title = Untersuchungen über die fossilen und subfossilen Cetaceen Europa's | year = 1873 | journal = Mémoires de l'Académie Impériale des Sciences de Saint-Petersbourg | series = 7 | volume = 20 | issue = 1 | pages = 1–372 | url = https://archive.org/stream/untersuchungen00brandt#page/n11/mode/2up | access-date = 17 December 2021 | language = de }}<!-- {{Harvnb|Brandt|1873}} --> **{{cite web |title=J. F. Brandt 1873 |website=Fossilworks |url=https://paleobiodb.org/classic/displayRefResults?reference_no=11981}} * {{Cite journal | last = Grateloup | first = J.-P. S. | author-link = Jean-Pierre Sylvestre de Grateloup | title = Description d'un fragment de machoire fossile, d'un genre nouveau de reptile (Saurien), de taille gigantesque, voisin de l'Iguanodon, trouvé dans le Grès marin, à Léognan, près Bordeaux (Gironde) | year = 1840 | journal = Actes de l'Académie nationale des sciences, belles-lettres et arts de Bordeaux | volume = 2 | pages = 201–210 | url = https://www.biodiversitylibrary.org/item/24631#page/8/mode/2up | access-date = 17 December 2021 }}<!-- {{Harvnb|Grateloup|1840}} --> **{{cite web |title=J. P. S. Grateloup 1840 |website=Fossilworks |url=https://paleobiodb.org/classic/displayRefResults?reference_no=29085}} * {{Cite book | last = Muizon | first = C. | chapter = River Dolphins, Evolutionary: History and Affinities | pages = [https://archive.org/details/encyclopediamari00perr/page/n1013 979]–986 | title = Encyclopedia of Marine Mammals | url = https://archive.org/details/encyclopediamari00perr | url-access = limited | editor1-last = Perrin | editor1-first = W. F. | editor2-last = Würsig | editor2-first = B. | editor3-last = Thewissen | editor3-first = J. G. M. | year = 2008 | publisher = Academic Press | edition = 2nd | isbn = 978-0-12-373553-9 }}<!-- {{Harvnb|Muizon|2008}} --> {{Refend}}
{{Odontoceti|O.}} {{Taxonbar|from=Q7581923}}
Category:Squalodontidae Category:Prehistoric toothed whales Category:Chattian first appearances Category:Miocene extinctions Category:Prehistoric mammal families
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