Cyprinodon

Cyprinodon is a genus of pupfishes found in waters that range from fresh to hypersaline. The genus is primarily found in Mexico, the Caribbean Islands and southern United States (Arizona, California, Florida, Nevada, New Mexico, Oklahoma and Texas), but C. variegatus occurs as far north as Massachusetts and along the entire Gulf of Mexico coastline, and C. dearborni and C. variegatus are found in northern South America. Many species have tiny ranges and are highly threatened, in some cases already extinct. Cyprinodon are small; the largest reaches in length and most other species only reach about half that size.

== Evolution == Based on phylogenetic evidence, Cyprinodon diverged from its closest relative, the recently extinct Megupsilon, during the Late Miocene, and saw a rapid evolutionary radiation afterwards. The only known fossil species from the genus is C. breviradius from the late Miocene or early Pliocene-aged sediments of Death Valley National Park (originally considered part of the Late Eocene-aged Titus Canyon Formation).