Cetartiodactyla is a group comprised of two orders of mammals that are superficially quite different and that, until recently, were recognized as two separate monophyletic clades. These orders are Artiodactyla, the even-toed ungulates, including animals such as cows (Bovidae), camels (Camelidae), and deer (Cervidae), and Cetacea, a group of mammals that are highly specialized for an aquatic lifestyle, including whales, dolphins (Delphinidae), and porpoises (Phocoenidae). Recent molecular evidence suggests that Cetacea evolved from artiodactyl ancestors. Making Artiodactyla non-monophyletic unless Cetacea is included. Experts suggest the monophyletic clade representing artiodactyls and cetaceans be called Cetartiodactyla. (Boisserie, Lihoreau, and Brunet, 2005; Gatesy et al., 1996; Gatesy et al., 1999; Gatesy, 1997; Graur and Higgins, 1994; Milinkovitch and Thewissan, 1997; Montgelard, Catzeflis, and Douzery, 1997; Naylor and Adams, 2001; O'Leary and Geisler, 1999; Shimamura et al., 1997; Thewissen, Williams, and Hussain, 2001)
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- Milinkovitch, M., J. Thewissan. 1997. Even-toed fingerprints on whale ancestry. Nature, 388: 622-624.
- Montgelard, C., F. Catzeflis, E. Douzery. 1997. Phylogenetic relationships of artiodactyls and cetaceans as deduced from the comparison of cytochrome b and 12S rRNA mitochondrial sequences. Molecular Biology and Evolution, 14(5): 550-559.
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- Thewissen, J., E. Williams, S. Hussain. 2001. Skeletons of terrestrial cetaceans and the relationship of whales to artiodactyls. Nature, 413: 277-281.