Abstract
The name “Cetartiodactyla” was proposed in 1997 to reflect the molecular data that suggested that Cetacea is closely related to Artiodactyla. Since then, that taxon has spread in popularity, even outside the scientific literature. However, the implications of the name are confusing, because Cetacea and Artiodactyla are not sister-taxa. Instead, the evidence clearly shows that cetaceans are a group embedded within Artiodactyla, not a sister-taxon of equal rank. It has long been accepted practice that systematists do not modify the names of higher groups when new subgroups are added to them. For example, Owen’s original concept of Artiodactyla did not change its name when more and more disparate taxa were added to it. Dinosauria did not become “Avedinosauria” when it became clear that birds are a subgroup of dinosaurs, nor did Reptilia become “Avereptilia”. In the interests of taxonomic priority and stability, and especially because the name is inherently misleading, we recommend that the name “Cetartiodactyla” be abandoned. If one wishes to make a reference to the fact that whales are now considered to be a subgroup of artiodactyls, they could be referred to informally as “whales and other artiodactyls” or “whales and terrestrial artiodactyls” without using a formal taxonomic name that is confusing and misleading.
Availability of data and material
All data are in the article.
References
Archibald JD (2003) Timing and biogeography of the eutherian radiation: Fossils and molecules compared. Mol Phylogenet Evol 28:350-359.
Árnason U, Adegoke JA, Bodin K, Born EW, Esa YB, Gullberg A, Nilsson M, Short RV, Xu X, Janke A (2002) Mammalian mitogenomic relationships and the root of the eutherian tree. Proc Natl Acad Sci USA 99(12):8151-8156.
Árnason U, Adegoke JA, Gullberg A, Harley EH, Janke A, Kullberg M (2008) Mitogenomic relationships of placental mammals and molecular estimates of their divergences. Gene 421(1-2):37-51.
Árnason U, Gullberg A, Gretarsdottir S, Ursing B, Janke A (2000) The mitochondrial genome of the sperm whale and a new molecular reference for estimating eutherian divergence dates. J Mol Evol 50(6):569-578.
Asher RJ, Helgen KM (2010) Nomenclature and placental mammal phylogeny. Evol Biol 10:102.
Boisserie JR, Lihoreau F, Brunet M (2005) The position of Hippopotamidae within Cetartiodactyla. Proc Natl Acad Sci USA 102 (5): 1537-1541.
Foss SE, Prothero DR (2007) Introduction. In: Prothero DR, and Foss SE (eds.), The Evolution of Artiodactyls. John Hopkins University Press, Baltimore, MD, pp. 1-3
Gatesy J, Hayashi C, Cronin MA, Arctander P (1996) Evidence from milk casein genes that cetaceans are close relatives of hippopotamid artiodactyls. Mol Biol Evol 13(7):954-963.
Geisler JH, MD Uhen (2003) Morphological support for close relationship between hippos and whales. J Vertebr Paleontol 23:991-996.
Geisler JH, MD Uhen (2005) Phylogenetic classification of extinct cetartiodactyls: results of simultaneous analysis of molecular, morphological, and stratigraphic data. J Mamm Evol 12:145-160.
Gingerich PD, Haq MU, Zalmout IS, Khan IH, Malkani MS (2001) Origin of whales from early artiodactyls: Hands and feet of Eocene Protocetidae from Pakistan. Science 293: 2239–2242.
Graur D, Higgins DG (1994) Molecular evidence for the inclusion of cetaceans within the order Artiodactyla. Mol Biol Evol 11(3):357-364.
Irwin DM, Árnason U (1994) Cytochrome b gene of marine mammals: Phylogeny and evolution. J Mamm Evol 2(1):37-55.
IUCN-SSC Cetacean Specialist Group (2021) What we do. https://iucn-csg.org/home/; accessed 24 July 2021.
Montgelard C, Catzeflis FM, Douzery E (1997) Phylogenetic relationships of artiodactyls and cetaceans as deduced from the comparison of cytochrome b and 12S rRNA mitochondrial sequences. Mol Biol Evol 14(5):550-559.
Murphy WJ, Pringle TH, Crider TA, Springer MS, Miller W (2007) Using genomic data to unravel the root of the placental mammal phylogeny. Genome Res 17(4):413-421.
O’Leary et al (2013) The placental mammal ancestor and the post-KPg radiation of placentals. Science 339: 662-668.
O'Leary MA, Orliac MJ, Spaulding M, Gatesy J (2020) Artiodactyla R. Owen 1848 [M. A. O'Leary, M. J. Orliac, M. Spaulding, and J. Gatesy], converted clade name. In: de Queiroz K, Cantino PD, and Gauthier JA (eds), Phylonyms: A Companion to the PhyloCode. CRC Press, Boca Raton, FL, pp. 949-954
Owen R (1848) Description of teeth and portions of jaws of two extinct Anthracotherioid quadrupeds (Hyopotamus vectianus and Hyop. bovinus) discovered by the Marchioness of Hastings in the Eocene deposits on the NW coast of the Isle of Wight: with an attempt to develop Cuvier's idea of the Classification of Pachyderms by the number of their toes. Q J Geol Soc Lond 4: 103–141.
Prasad AB, Allard MW, Program NCS, Green ED (2008) Confirming the phylogeny of mammals by use of large comparative sequence data sets. Mol Biol Evol 25(9):1795-1808.
Simpson GG (1945) The principles of classification and a classification of mammals. Bull Am Mus Nat Hist 85:1-350.
Spaulding M, O'Leary MA, Gatesy J (2009) Relationships of Cetacea (Artiodactyla) among mammals: increased taxon sampling alters interpretations of key fossils and character evolution. PLoS One 4(9): e7062. https://doi.org/10.1371/journal.pone.0007062
Stanhope MJ, Waddell VG, Madsen O, de Jong W, Hedges SB, Cleven GC, Kao D, Springer MS (1998) Molecular evidence for multiple origins of Insectivora and for a new order of endemic African insectivore mammals. Proc Natl Acad Sci USA 95(17):9967-9972.
Theodor JM, Foss SE (2005) Deciduous dentition of Eocene cebochoerid artiodactyls and cetartiodactyl relationships. J Mamm Evol 12: 161-181.
Thewissen JGM, Williams EM, Roe LJ, Hussain ST (2001) Skeletons of terrestrial cetaceans and the relationship of whales to artiodactyls. Nature 413: 277–281.
Waddell PJ, Okada N, Hasegawa M (1999) Towards resolving the interordinal relationships of placental mammals. Syst Biol 48(1):1-5.
Waddell PJ, Shelley S (2003) Evaluating placental inter-ordinal phylogenies with novel sequences including RAG1, gamma-fibrinogen, ND6, and mt-tRNA, plus MCMC-driven nucleotide, amino acid, and codon models. Mol Phylogenet Evol 28(2):197-224.
Acknowledgements
We thank J. Gatesy, R. Asher, E. Bärmann, and two anonymous reviewers for helpful comments on an earlier draft of this paper.
Author information
Authors and Affiliations
Corresponding author
Ethics declarations
Ethics approval
Not applicable.
Consent to participate
Not applicable.
Consent for publication
Not applicable
Conflicts of interest/Competing interests
None.
Rights and permissions
About this article
Cite this article
Prothero, D.R., Domning, D., Fordyce, R.E. et al. On the Unnecessary and Misleading Taxon “Cetartiodactyla”. J Mammal Evol 29, 93–97 (2022). https://doi.org/10.1007/s10914-021-09572-7
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10914-021-09572-7