Project 2439: M. Martinez-Caceres, O. Lambert, C. de Muizon. 2017. The anatomy and phylogenetic affinities of Cynthiacetus peruvianus, a large Dorudon-like basilosaurid (Cetacea, Mammalia) from the late Eocene of Peru. Geodiversitas. 39 (1):7-163.
Specimen: † Cynthiacetus peruvianus (MNHN/F:PRU 10)
View: Left anterolateral view

Abstract

Cynthiacetus peruvianus is a Dorudon-like basilosaurid (Cetacea, Basilosauridae), being one of the largest members of the family. The holotype of this species is a sub-complete skeleton, which comes from the late Eocene (Priabonian) of the Otuma Formation on the southern coast of Peru. A thorough description of this specimen is presented here. C. peruvianus differs from the other species of the genus (C. maxwelli) in having fewer accessory cusps on the distal and mesial edges of p3 and p4. Its skull shows the general pattern of the basilosaurid skull, which is relatively monotonous across the whole family, but it is much larger than those of Dorudon and Zygorhiza, and slightly smaller and distinctly more slender than that of Basilosaurus. The most characteristic features of C. peruvianus stand on the postcranial skeleton: it presents large vertebrarterial foramina on the cervical vertebrae; it lacks a ventral expansion of the transverse processes of C3-C5; it presents the greatest number of thoracic vertebrae (20) observed in cetaceans; and its first thoracics have an almost vertical neural spine. The second part of the monograph is devoted to evolutionary trends and phylogenetic relationships of Archaeocetes with a special focus on Basilosauridae. Some of the major trends considered concern, the rostrum morphology, the asymmetry of the rostrum, the supraorbital region, the neurocranium, the pelvic girdle and hind limb, and the chevrons. A parsimony analysis confirms the monophyly of the Basilosauridae, which are supported by four unambiguous synapomorphies: the presence of well-defined embrasure pits between the upper incisors, a narrow palate anterior to P4, a cleft on the mesial edge of the lower molars, and more than 13 thoracic vertebrae. In contrast with previous hypotheses, in which Saghacetus was the sister taxon of the Pelagiceti, the results of our analysis reveal this taxon as the most basal basilosaurid. In all the analyses performed Cynthiacetus forms a clade with Dorudon and Basilosaurus, being almost constantly the sister taxon of Basilosaurus.
Key words: Basilosauridae, Late Eocene, Peru, Anatomy, Phylogeny


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Article DOI: https://doi.org/10.5252/g2017n1a1

Project DOI: 10.7934/P2439, http://dx.doi.org/10.7934/P2439
This project containsMatrices
  • 1 Media
  • 1 Matrix
  • 1 Document
  • 41 Taxa
  • 1 Specimen
  • 101 Characters
Total size of project's media files: 1 MB

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Total scored cells: 2098
Total media associated with cells: 0
Total labels associated with cell media: 0
Characters
Total characters: 101
Total characters with associated media: 0
Total characters with media with labels: 0
Total character states: 275
Total character states with associated media: 0
Total character states with media with labels:0
Total unordered/ordered characters:6/95
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    Christian Muizon
    Project Administrator
    Last logged in 09/28/17
    4111010100002098
    (2098, 0, 0)
    00000
    Olivier Lambert
    Full membership
    Last logged in 09/28/16
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    (0, 0, 0)
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    Taxonomic Overview for Matrix 'M24324' (32 Taxa)

    taxon unscored
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    [1] † Pakicetidae
    Last Modified in 10/31/16
    41626000002
    [2] † Ambulocetidae
    Last Modified in 10/31/16
    67343400002
    [3] † Remingtonocetidae
    Last Modified in 10/31/16
    41616000002
    [4] † Artiocetus clavus
    Last Modified in 09/28/17
    34686700002
    [5] † Rodhocetus kasrani
    Last Modified in 09/28/17
    26777500002
    [6] † Carolinacetus gingerichi
    Last Modified in 10/31/16
    65373600002
    [7] † Protocetus atavus
    Last Modified in 09/28/17
    36656500002
    [8] † Georgiacetus vogtlensis
    Last Modified in 10/31/16
    13898800002
    [9] † Basilosaurus cetoides
    Last Modified in 10/31/16
    8939300002
    [10] † Basilosaurus isis
    Last Modified in 10/31/16
    26767500002
    [11] † Dorudon atrox
    Last Modified in 10/31/16
    5999600002
    [12] † Zygorhiza kochii
    Last Modified in 09/28/17
    12938900002
    [13] † Cynthiacetus peruvianus
    Last Modified in 10/31/16
    110010000002
    [14] † Chrysocetus healyorum
    Last Modified in 10/31/16
    78232300002
    [15] † Saghacetus osiris
    Last Modified in 10/31/16
    28747300002
    [16] † Ancalecetus simonsi
    Last Modified in 10/31/16
    64373700002
    [17] † MUSM 1917
    Last Modified in 09/28/17
    37656400002
    [18] † Mammalodon colliveri
    Last Modified in 10/31/16
    36666500002
    [19] † Janjucetus hunderi
    Last Modified in 10/31/16
    32696900002
    [20] † Aetiocetus weltoni
    Last Modified in 10/31/16
    32716900002
    [21] † Aetiocetus cotylalveus
    Last Modified in 10/31/16
    39626200002
    [22] † Chonecetus goedertorum
    Last Modified in 10/31/16
    41606000002
    [23] † ChM pv 5720
    Last Modified in 09/28/17
    33686800002
    [24] † Eomysticetus withmorei
    Last Modified in 09/28/17
    38646300002
    [25] † Simocetus rayii
    Last Modified in 10/31/16
    26767500002
    [26] † Agorophius spp
    Last Modified in 09/28/17
    50535100002
    [27] † Archaeodelphis patrius
    Last Modified in 10/31/16
    69323200002
    [28] † Xenorophus sloani
    Last Modified in 09/28/17
    64373700002
    [29] † Echovenator sandersii
    Last Modified in 10/31/16
    23787800002
    [30] † Albertocetus meffordorum
    Last Modified in 10/31/16
    50515100002
    [31] † Squalodon calvertensis
    Last Modified in 10/31/16
    26767500002
    [32] † Waipatia maerewhenua
    Last Modified in 10/31/16
    20828100002


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