Project 200: M. A. O'Leary, J. H. Geisler. 1998. The Position of Cetacea Within Mammalia: Phylogenetic Analysis of Morphological Data from Extinct and Extant Taxa. Systematic Biology. 48 (3):455-490.
Specimen: † Andrewsarchus (AMNH/VP:20135)
View: skull, lateral

Abstract

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 biological form and function that accompanied the shift from fully terrestrial to fully aquatic life in this clade. Phylogenies based on molecular data and those based on morphological data both place cetaceans among ungulates but are incongruent in other respects. Morphologists argue that cetaceans are most closely related to mesonychians, an extinct group of terrestrial ungulates. They have disagreed, however, as to whether Perissodactyla (odd-toed ungulates) or Artiodactyla (even-toed ungulates) is the extant clade most closely related to Cetacea, and have long maintained that each of these orders is monophyletic. The great majority of molecule-based phylogenies show, by contrast, not only that artiodactyls are the closest extant relatives of Cetacea, but also that Artiodactyla is paraphyletic unless cetaceans are nested within it, often as the sister group of hippopotamids. We tested morphological evidence for several hypotheses concerning the sister taxon relationships of Cetacea in a maximum parsimony analysis of 123 morphological characters from 10 extant and 30 extinct taxa. We advocate treating certain multistate characters as ordered because such a procedure incorporates information about hierarchical morphological transformation. In all most-parsimonious trees, whether multistate characters are ordered or unordered, Artiodactyla is the extant sister taxon of Cetacea. With certain multistate characters ordered, the extinct clade Mesonychia (Mesonychidae + Hapalodectidae) is the sister taxon of Cetacea, and Artiodactyla is monophyletic. When all fossils are removed from the analysis, Artiodactyla is paraphyletic with Cetacea nested inside, indicating that inclusion of mesonychians and other extinct stem taxa in a phylogenetic analysis of the ungulate clade is integral to the recovery of artiodactyl monophyly. Phylogenies derived from molecular data alone may risk recovering inconsistent branches because of an inability to sample extinct clades, which by a conservative estimate, amount to 89% of the ingroup. Addition of data from recently described astragali attributed to cetaceans does not overturn artiodactyl monophyly.


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Article DOI: doi: 10.1080/106351599260102

Project DOI: 10.7934/P200, http://dx.doi.org/10.7934/P200
This project containsMatrices
  • 1 Media
  • 1 Matrix
  • 42 Taxa
  • 1 Specimen
  • 123 Characters
Total size of project's media files: 3 MB

Download Project SDD File
Total scored cells: 3545
Total media associated with cells: 0
Total labels associated with cell media: 0
Characters
Total characters: 123
Total characters with associated media: 0
Total characters with media with labels: 0
Total character states: 289
Total character states with associated media: 0
Total character states with media with labels:0
Total unordered/ordered characters:123/0
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MorphoBank Project 200


    Members

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    Maureen O'Leary
    Project Administrator
    Last logged in 05/14/15
    421101230003545
    (3545, 0, 0)
    0000


    Taxonomic Overview for Matrix 'M563' (40 Taxa)

    taxon unscored
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    [1] Tursiops
    Last Modified in 12/05/13
    64595900001
    [2] Balaenoptera
    Last Modified in 12/05/13
    65585800001
    [3] † Dorudon
    Last Modified in 05/14/15
    33919000001
    [4] Basilosaurus
    Last Modified in 12/05/13
    29959400001
    [5] † Protocetus
    Last Modified in 05/14/15
    70535300001
    [6] † Cross whale
    Last Modified in 05/14/15
    83414000001
    [7] † Remingtonocetus
    Last Modified in 05/14/15
    78464500001
    [8] † Ambulocetus
    Last Modified in 05/14/15
    58676500001
    [9] † Pakicetus
    Last Modified in 05/14/15
    58676500001
    [10] † Harpagolestes
    Last Modified in 05/14/15
    52727100001
    [11] † Synoplotherium
    Last Modified in 05/14/15
    36888700001
    [12] † Mesonyx
    Last Modified in 05/14/15
    2110310200001
    [13] † Pachyaena
    Last Modified in 05/14/15
    36928700001
    [14] † Sinonyx
    Last Modified in 05/14/15
    50737300001
    [15] † Ankalagon
    Last Modified in 05/14/15
    71525200001
    [16] † Dissacus
    Last Modified in 05/14/15
    49767400001
    [17] † Hapalodectes
    Last Modified in 05/14/15
    57686600001
    [18] † Eoconodon
    Last Modified in 05/14/15
    48767500001
    [19] † Andrewsarchus
    Last Modified in 05/14/15
    93323000001
    [20] Tragulus
    Last Modified in 12/05/13
    811911500001
    [21] Ovis
    Last Modified in 12/05/13
    611711700001
    [22] Camelus
    Last Modified in 12/05/13
    411911900001
    [23] † Poebrotherium
    Last Modified in 05/14/15
    1410910900001
    [24] † Agriochoerus
    Last Modified in 05/14/15
    1910610400001
    [25] Sus
    Last Modified in 12/05/13
    312012000001
    [26] † Hexaprotodon
    Last Modified in 05/14/15
    1610810700001
    [27] Hippopotamus
    Last Modified in 12/05/13
    811711500001
    [28] † Elomeryx
    Last Modified in 05/14/15
    1510810800001
    [29] † Archaeotherium
    Last Modified in 05/14/15
    1411010900001
    [30] † Diacodexis
    Last Modified in 05/14/15
    2110410200001
    [31] Equus
    Last Modified in 12/05/13
    1211111100001
    [32] † Hyracotherium
    Last Modified in 05/14/15
    2010410300001
    [33] † Heptodon
    Last Modified in 05/14/15
    26979700001
    [34] † Meniscotherium
    Last Modified in 05/14/15
    251009800001
    [35] † Phenacodus
    Last Modified in 05/14/15
    2010610300001
    [36] † Hyopsodus
    Last Modified in 05/14/15
    26989700001
    [37] † Arctocyon
    Last Modified in 05/14/15
    26979700001
    [38] † Leptictis
    Last Modified in 05/14/15
    2110210200001
    [39] † Asioryctes
    Last Modified in 05/14/15
    45797800001
    [40] Didelphis
    Last Modified in 12/05/13
    1810510500001


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