Editing Basilosaurus (section)

=== Spine and movement ===
A complete ''Basilosaurus'' skeleton was found in 2015, and several attempts have been made to reconstruct the vertebral column from partial skeletons. {{Harvnb|Kellogg|1936}} estimated a total of 58 vertebrae, based on two partial and nonoverlapping skeletons of ''B. cetoides'' from Alabama. More complete fossils uncovered in Egypt in the 1990s allowed a more accurate estimation: the vertebral column of ''B. isis'' has been reconstructed from three overlapping skeletons to a total of 70 vertebrae with a vertebral formula interpreted as seven cervical, 18 thoracic, 20 lumbar and sacral, and 25 caudal vertebrae. The vertebral formula of ''B. cetoides'' can be assumed to be the same.<ref name=zalmout2000/>
[[File:Basilosaurus cetoides.png|thumb|left|[[Paleoart|Restoration]] of ''Basilosaurus cetoides'']]
''Basilosaurus'' has an anguilliform ([[eel]]-like) body shape because of the elongation of the [[Body of vertebra|centra]] of the thoracic through anterior caudal vertebrae. In life, these vertebrae were filled with marrow, and because of the enlarged size, this made them buoyant. ''Basilosaurus'' probably swam predominantly in two dimensions at the sea surface, in contrast to the smaller ''[[Dorudon]]'', which was likely a diving, three-dimensional swimmer.<ref>{{Cite book| last = Gingerich| first = P. D.| chapter = Paleobiological Perspectives on Mesonychia, Archaeoceti, and the Origin of Whales| pages = 424–439| title = The Emergence of Whales: Evolutionary Patterns in the Origin of Cetacea| series = Advances in Vertebrate Paleobiology| volume = 1| editor-last = Thewissen| editor-first = J. G. M.| year = 1998| publisher = Springer| chapter-url = http://www-personal.umich.edu/~gingeric/PDFfiles/PDG341_OriginWhales.pdf| isbn = 9780306458538| access-date = 8 September 2013| archive-date = 18 May 2022| archive-url = https://web.archive.org/web/20220518203140/http://www-personal.umich.edu/~gingeric/PDFfiles/PDG341_OriginWhales.pdf| url-status = live}}</ref> The skeletal anatomy of the tail suggests that a small fluke was probably present, which would have aided only vertical motion.<ref>{{cite web |title=Basilosaurus spp. |url=https://www.nyit.edu/medicine/basilosaurus_spp |website=College of Osteopathic Medicine |publisher=Robert Boessenecker and Jonathan Geisler |access-date=22 June 2019 |archive-date=31 December 2018 |archive-url=https://web.archive.org/web/20181231105613/https://www.nyit.edu/medicine/basilosaurus_spp |url-status=live }}</ref>

Similarly sized thoracic, lumbar, sacral, and caudal vertebrae imply that it moved in an [[Fish locomotion#Swimming|anguilliform]] fashion, but predominantly in the vertical plane. Paleontologist [[Philip D. Gingerich]] theorized that ''Basilosaurus'' may also have moved in a very odd, horizontal anguilliform fashion to some degree, something completely unknown in modern cetaceans. The vertebrae appear to have been hollow, and likely also fluid-filled. This would imply that ''Basilosaurus'' typically functioned in only two dimensions at the ocean surface, compared with the three-dimensional habits of most other cetaceans. Judging from the relatively weak axial musculature and the thick bones in the limbs, ''Basilosaurus'' is not believed to have been capable of sustained swimming or deep diving, or [[terrestrial locomotion]].<ref>{{cite book |title=Great Transformations in Vertebrate Evolution |date=July 2015 |publisher=KENNETH P. DIAL, NEIL SHUBIN, AND ELIZABETH L. BRAINERD |isbn=9780226268255 |url=https://books.google.com/books?id=zb5TCgAAQBAJ&q=basilosaurus+moved+like+an+eel&pg=PA248}}</ref>