Cynthiacetus

{{Automatic taxobox

| fossil_range = Late Eocene
~{{Fossil range|40.4|33.9}}

| image = Museum of Natural History Cynthiacetus.jpg

| image_caption = Skeleton at the MNHN, Paris

| taxon = Cynthiacetus

| authority = {{Harvnb|Uhen|2005}}

| subdivision_ranks = Species

| subdivision =

{{Extinct}}C. maxwelli (type)
{{Harvnb|Uhen|2005}}
{{Extinct}}C. peruvianus
{{Harvnb|Martínez-Cáceres|de Muizon|2011}}

}}

Cynthiacetus is an extinct genus of basilosaurid early whale that lived during the Late Eocene (Bartonian-Priabonian, {{Mya|40.4|33.9}}.){{Paleodb|63144|Cynthiacetus maxwelli}}. Retrieved July 2013. Specimens have been found in the southeastern United States and Peru (Otuma Formation).{{Harvnb|Martínez-Cáceres|de Muizon|2011|loc=Abstract}}

Discovery and naming

File:Cynthiacetus peruvianus skull.JPG, Paris]]

Cynthiacetus was named after the town of Cynthia, Mississippi, close to where the type specimen for the species C. maxwelli was discovered.

Description

File:Cynthiacetus maxwelli.png]]

The skull of C. maxwelli was similar in size and morphology to that of Basilosaurus cetoides, but Cynthiacetus lacked the elongated vertebrae of Basilosaurus. {{Harvnb|Uhen|2005}} erected the genus to avoid the nomen dubium Pontogeneus (which was based on poorly described and now vanished specimens).{{Harvnb|Uhen|2008|p=93}} Cynthiacetus was smaller than Masracetus.{{Harvnb|Gingerich|2007|p=375}}

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). The type specimen of C. peruvianus belonged to an adult individual measuring around {{cvt|9|m|ft}} long and weighing up to {{convert|4|MT|ST}}.{{cite journal|last1=Martínez-Cáceres|first1=M.|last2=Lambert|first2=O.|last3=De Muizon|first3=C.|title=The anatomy and phylogenetic affinities of Cynthiacetus peruvianus, a large Dorudon-like basilosaurid (Cetacea, Mammalia) from the late Eocene of Peru|year=2017|journal=Geodiversitas, Museum National d'Histoire Naturelle Paris|volume=39|issue=1|pages=7–163|doi=10.5252/g2017n1a1|s2cid=90142285 |url=https://hal.archives-ouvertes.fr/hal-03424280/file/181-2017%20Marti%CC%81nez-Ca%CC%81ceres%20et%20al..pdf}}{{cite journal|author1=Paul, G.S.|author2=Larramendi, A.|year=2025|title=Further trimming down the marine heavyweights: Perucetus colossus did not come close to, much less exceed, the tonnage of blue whales, and the latter are not ultra-sized either|journal=Palaeontologia Electronica|volume=28|issue=1|at=28.1.a6|doi=10.26879/1435|url=https://palaeo-electronica.org/content/2025/5431-trimming-down-perucetus|doi-access=free}}