The Phylogenetic Position of Cetaceans: Further Combined Data Analyses, Comparisons with the Stratigraphic Record and a Discussion of Character Optimization1

  title={The Phylogenetic Position of Cetaceans: Further Combined Data Analyses, Comparisons with the Stratigraphic Record and a Discussion of Character Optimization1},
  author={Maureen A O'Leary},
Abstract A recent total evidence analysis of the position of cetaceans (whales, dolphins and porpoises and extinct relatives) among mammals indicated that the phylogeny of these taxa remains poorly resolved. Molecular data show that 1) the order Artiodactyla (even-toed ungulates) is paraphyletic unless whales are included within it and 2) that the traditional relationships of clades within Artiodactyla are not supported. This controversy also affects the position of a wholly extinct clade… 
Phylogenetic Relationships of Extinct Cetartiodactyls: Results of Simultaneous Analyses of Molecular, Morphological, and Stratigraphic Data
Both analyses supported the exclusion of Mesonychia from Cetartiodactyla and a close phylogenetic relationship between Hippopotamidae and Cetacea, and added stratigraphic information to the intrinsic dataset, which found fewer most parsimonious trees.
A Total Evidence Phylogeny of the Arctoidea (Carnivora: Mammalia): Relationships Among Basal Taxa
  • J. Finarelli
  • Biology, Environmental Science
    Journal of Mammalian Evolution
  • 2008
Phylogenetic positions for fossil taxa indicate that several taxa previously described as early members of extant families (e.g., Bathygale and Plesictis) are likely stem taxa at the base of the Arctoidea.
Relationships of Cetacea (Artiodactyla) Among Mammals: Increased Taxon Sampling Alters Interpretations of Key Fossils and Character Evolution
The phylogenetic position of †Indohyus suggests that the cetacean stem lineage included herbivorous and carnivorous aquatic species, and the taxonomy of living and extinct artiodactylans is revised and proposes explicit node and stem-based definitions for the ingroup.
A complete phylogeny of the whales, dolphins and even‐toed hoofed mammals (Cetartiodactyla)
The present species‐level tree of the Cetartiodactyla provides the first opportunity to examine comparative hypotheses across entirely aquatic and terrestrial species within a single mammalian order.
The emergence of cetaceans: phylogenetic analysis of male social behaviour supports the Cetartiodactyla clade
  • D. Lusseau
  • Biology
    Journal of evolutionary biology
  • 2003
The behavioural evidence supports the inclusion of cetaceans in Artiodactyla, and the behaviour observed during male agonistic interactions in placental mammals was considered to determine which of these hypotheses was supported by the behaviour of extant species.
▪ Abstract A review of crocodylian phylogeny reveals a more complex history than might have been anticipated from a direct reading of the fossil record without consideration of phylogenetic
Origins of Hippopotamidae (Mammalia, Cetartiodactyla): towards resolution
A cladistic analysis of characters used in the literature to support one, the other, or both hypotheses were re‐examined in light of a better known primitive hippopotamid morphology, finding the family Anthracotheriidae remains the best putative hippopotamus stem group on the basis of the reviewed characters.
The position of Hippopotamidae within Cetartiodactyla.
This morphological analysis of a comprehensive set of taxa and characters offers a robust solution to the origins of Hippopotamidae, which appears to be deeply nested within the otherwise extinct artiodactyl family Anthracotheriidae, most precisely within the most advanced selenodont forms.
It is reported that morphological data from extinct and extant taxa support placement of Cetacea within Artiodactyla as the closest relatives of Hippopotamidae and indicate that molecular and morphological evidence for the phylogeny of these taxa are now much more congruent than previously thought.
Morphology, paleontology, and placental mammal phylogeny.
How “morphology” has not yet been fully exploited as a source of data for phylogenetic research is discussed, including their use of congruence of individual partitions to a “true” tree and their generalization across morphological data sets based on their evaluation of one matrix.


The position of Cetacea within mammalia: phylogenetic analysis of morphological data from extinct and extant taxa.
Knowledge of the phylogenetic position of the order Cetacea (whales, dolphins, and porpoises) within Mammalia is of central importance to evolutionary biologists studying the transformations of
Stability of cladistic relationships between Cetacea and higher-level artiodactyl taxa.
Perturbations of the combined matrix show that the above clades are stable to a variety of disturbances and cladistic relationships between Cetacea and artiodactyls have been stable to increased taxonomic sampling and to the addition of more than 1,400 informative characters from 15 data sets.
Parsimony Analysis of Total Evidence from Extinct and Extant Taxa and the Cetacean-Artiodactyl Question (Mammalia, Ungulata)☆
In the total evidence analysis the parameter most congruent with the overall character data is unresolved as to the sister taxon of Cetacea; however, the Adams consensus tree favors the neontological result.
A Concern for Evidence and a Phylogenetic Hypothesis of Relationships among Epicrates (Boidae, Serpentes)
High levels of character congruence were observed among 89 biochemical and morphological synapomorphies scored on 10 species of Epicrates, and the consensus cladogram was consistent with the phylogenetic interpretation attached to the resulting hypothesis, which is a consensus of two equally parsimonious cladograms.
Molecular evidence from retroposons that whales form a clade within even-toed ungulates
An extensive survey of retropositional events that might have occurred during the divergence of whales and even-toed ungulates is made, providing evidence that whales, ruminants and hippopotamuses form a monophyletic group.
The time of origin of whales and the role of behavioral changes in the terrestrial-aquatic transition
Primitive features of Nalacetus, the large number of synapomorphies diagnosing Cetacea, and the implied ghost lineage suggest that the early cetacean radiation was much more extensive than has been previously recognized.
Implications of Deltatheridium specimens for early marsupial history
The presence of specialized marsupial patterns of tooth replacement and cranial vascularization in Deltatheridium and the basal phylogenetic position of this taxon indicate that these features are characteristic of Metatheria as a whole.
Evidence from milk casein genes that cetaceans are close relatives of hippopotamid artiodactyls.
Phylogenetic analyses of the casein data suggest that hippopotamid artiodactyls are more closely related to cetaceans than to other artiodactoryls (even-toed hoofed mammals), and an analysis of the nuclear casein sequences combined with published mitochondrial cytochrome b DNA sequences also supports the Cetacea/Hippopotamidae sister group.
Whale ankles and evolutionary relationships
These two hypotheses are not mutually exclusive, because mesonychians and cetaceans could be sister groups, and this combined clade (Cete) could be the sister group to a group of artiodactyls.
Evidence from the digestive tract on phylogenetic relationships in ungulates and whales
Following consideration of 20 morphological parameters of the gastrointestinal tract of ungulates and Cetacea, phylogenetic trees were constructed for baleen whales, toothed whales and beaked whales, as well as for four taxa of the PSHM group.