The skull of C. maxwelli was similar in size and morphology to that of Basilosaurus cetoides, but Cynthiacetus lacked the elongated vertebrae of Basilosaurus. Uhen 2005 erected the genus to avoid the nomen dubiumPontogeneus (which was based on poorly described and now vanished specimens).[3]Cynthiacetus was smaller than Masracetus.[4]
The South American species C. peruvianus, the first archaeocete to be described on that continent, mainly differs from C. maxwelli in the number of cuspids in the lower premolars, but it also has the greatest numbers of thoracic vertebrae (20).[2] The type specimen of C. peruvianus belonged to an adult individual measuring 9 m (30 ft) long.[5]
Martínez-Cáceres, Manuel; de Muizon, Christian (2011). "A new basilosaurid (Cetacea, Pelagiceti) from the Late Eocene to Early Oligocene Otuma Formation of Peru". Comptes Rendus Palevol. 10 (7): 517–526. Bibcode:2011CRPal..10..517M. doi:10.1016/j.crpv.2011.03.006. OCLC802202947.
Uhen, Mark D. (2005). "A new genus and species of archaeocete whale from Mississippi". Southeastern Geology. 43 (3): 157–172.
Uhen, Mark D. (2008). "Basilosaurids". In Perrin, William F.; Wursig, Bernd J.; Thewissen, J.G.M. (eds.). Encyclopedia of Marine Mammals (2 ed.). Academic Press. pp. 91–94. ISBN978-0-12-373553-9.
