Editing Basilosaurus (section)

{{short description|Prehistoric cetacean genus from the Late Eocene epoch}}
{{Use dmy dates|date=January 2025}}
{{Automatic taxobox
| name = ''Basilosaurus''
| fossil_range = [[Eocene]] ([[Bartonian]] to [[Priabonian]]), {{Fossil range|41.3|33.9}}<ref>{{cite web |title=Dir Abu Lifa (Eocene of Egypt) |url=https://paleobiodb.org/classic/basicCollectionSearch?collection_no=40516&is_real_user=1 |website=PBDB |publisher=Mark Uhen |access-date=14 May 2019 |archive-date=18 July 2020 |archive-url=https://web.archive.org/web/20200718085053/https://www.paleobiodb.org/classic/basicCollectionSearch?collection_no=40516&is_real_user=1 |url-status=live }}</ref>
| image = Basilosaurus cetoides (1).jpg
| image_upright = 1.15
| image_caption = ''B. cetoides'' skeleton, [[National Museum of Natural History]], [[Washington DC]]
| taxon = Basilosaurus
| authority = {{Harvnb|Harlan|1834}}
| subdivision_ranks = Species
| subdivision = * ''B. cetoides'' ([[Type species|type]])<br /><small>{{Harvnb|Owen|1839}}</small>
* ''B. isis''<br /><small>{{Harvnb|Andrews|1904}}</small>
| synonyms = * ''Zeuglodon''<br /><small>{{Harvnb|Owen|1839}}</small>
* ''Hydrarchos''?<br /><small>{{Harvnb|Koch|1845}}</small>
* ''Alabamornis''<br /><small>{{Harvnb|Abel|1906}}</small>
}}

'''''Basilosaurus''''' (meaning "king lizard") is a [[genus]] of large, predatory, prehistoric [[Archaeoceti|archaeocete]] whale from the late [[Eocene]], approximately 41.3 to 33.9 [[mya (unit)|million years ago]] (mya). First described in 1834, it was the first archaeocete and prehistoric whale known to science.<ref name="Uhen-20022"/> Fossils attributed to the [[type species]] ''B. cetoides'' were discovered in the southeastern [[United States]]. They were originally thought to be of a giant reptile, hence the suffix "-saurus", [[Ancient Greek]] for "lizard". The animal was later found to be an early [[marine mammal]], prompting attempts at renaming the creature, which failed as the [[International Code of Zoological Nomenclature#Principle of priority|rules of zoological nomenclature]] dictate using the original name given. The second species named in 1904, ''B. isis'', lived in the region currently known as the [[Mediterranean Sea]], with fossils found in [[North Africa]] and [[Jordan]].

''Basilosaurus'' is thought to have been one of the largest animals of the [[Paleogene]], with the type species ''B. cetoides'' measuring around {{convert|17|-|20|m|ft}} long and weighing up to {{convert|15|MT|ST}}. It was the top predator of its environment in the shallows of the inland sea, preying on sharks, large fish and other marine mammals. The smaller dolphin-like relative ''[[Dorudon]]'' seems to have been the predominant food source of ''Basilosaurus'' based on its stomach contents and the bite marks preserved in the skull of ''Dorudon''.

''Basilosaurus'' was at one point a [[wastebasket taxon]] before the genus slowly started getting reevaluated, with many species of different Eocene cetacean being assigned to the genus in the past. However, most are invalid or have been reclassified under a new or different genus, leaving only two confirmed species.
''Basilosaurus'' may have been one of the first fully aquatic cetaceans,<ref name="Uhen-20022">{{Cite book | last = Uhen | first = Mark D. | chapter = Basilosaurids | pages = [https://archive.org/details/encyclopediaofma2002unse/page/79 79–81] | title = Encyclopedia of Marine Mammals | editor1-last = Perrin | editor1-first = William F. | editor2-last = Würsig | editor2-first = Bernd | editor3-last = Thewissen | editor3-first = J. G. M. | year = 2002 | publisher = Academic Press | isbn = 978-0-12-551340-1 | chapter-url = https://archive.org/details/encyclopediaofma2002unse/page/79 }}</ref> sometimes referred to as the Pelagiceti.<ref>{{cite web |title=Clade Pelagiceti Uhen 2008 (whale) |url=https://paleobiodb.org/classic/checkTaxonInfo?taxon_no=134057&is_real_user=1 |website=PBDB}}</ref> ''Basilosaurus'', unlike modern cetaceans, had various types of teeth–such as [[canine tooth|canines]] and [[molar (tooth)|molar]]s–in its mouth ([[heterodonty]]), and it probably was able to chew its food, in contrast to modern cetaceans which swallow their food whole.<ref>{{cite web |title=HOW DOES DIGESTION TAKE PLACE IN WHALES? |url=https://baleinesendirect.org/en/how-does-digestion-take-place-in-whales/ |website=Whales, online|date=15 July 2015 }}</ref><ref>{{cite web |title=Basilosaurus the Bone-Crusher |url=https://www.nationalgeographic.com/science/phenomena/2015/03/06/basilosaurus-the-bone-crusher/ |archive-url=https://web.archive.org/web/20190807213408/https://www.nationalgeographic.com/science/phenomena/2015/03/06/basilosaurus-the-bone-crusher/ |url-status=dead |archive-date=7 August 2019 |website=National geographic|date=6 March 2015 }}</ref>