Psettodoidea and pleuronectoidea (Pisces, Heterosomata) : Nielsen, J., 1961. Atlantide Rep. 6: 101–127

Abstract

The family Delphinidae is one of three extant families (with Phocoenidae and Monodontidae) in the cetacean superfamily Delphinoidea (which also includes two extinct families, Kentriodontidae and Albireonidae). Delphinids likely arose in the mid- to late Miocene (11–12 mya) from kentriodontid-like ancestors and quickly radiated into many different morphological and ecological types. Today the Delphinidae is the most speciose family of marine mammals, with 33–35 recognized extant species arranged into 17–19 genera. At present, there is much uncertainty about the evolutionary relationships among the species of delphinids. Of the many recent classifications that have been proposed, two are depicted here. One represents a more traditional view of dolphin taxonomy, and the other is a revised classification based on various recent molecular and morphological phylogenetic analyses. Delphinids also show wide variation in their external morphology. Only a few species (e.g., Orcinus orca, Globicephala spp.) are dramatically sexually dimorphic, although many others may have subtler dimorphism in body size and shape, coloration, and dorsal fin shape.