Project 2436: R. M. D. Beck. 2017. The Skull of Epidolops ameghinoi from the Early Eocene Itaboraí Fauna, Southeastern Brazil, and the Affinities of the Extinct Marsupialiform Order Polydolopimorphia. Journal of Mammalian Evolution. 24 (4):373-414.
Specimen: † Epidolops ameghinoi (DGM/M:DGM 321-M)
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Abstract

The skull of the polydolopimorphian marsupialiform Epidolops ameghinoi is described in detail for the first time, based on a single well-preserved cranium and associated left and right dentaries plus additional craniodental fragments, all from the early Eocene (53–50 million year old) Itaboraí fauna in southeastern Brazil. Notable craniodental features of E. ameghinoi include absence of a masseteric process, very small maxillopalatine fenestrae, a prominent pterygoid fossa enclosed laterally by a prominent ectopterygoid crest, an absent or tiny transverse canal foramen, a simple, planar glenoid fossa, and a postglenoid foramen that is immediately posterior to the postglenoid process. Most strikingly, the floor of the hypotympanic sinus was apparently unossified, a feature found in several stem marsupials but absent in all known crown marsupials. "Type II" marsupialiform petrosals previously described from Itaboraí plausibly belong to E. ameghinoi; in published phylogenetic analyses, these petrosals fell outside (crown-clade) Marsupialia. "IMG VII" tarsals previously referred to E. ameghinoi do not share obvious synapomorphies with any crown marsupial clade, nor do they resemble those of the only other putative polydolopimorphians represented by tarsal remains, namely the argyrolagids. Most studies have placed Polydolopimorphia within Marsupialia, related to either Paucituberculata, or to Microbiotheria and Diprotodontia. However, diprotodonty almost certainly evolved independently in polydolopimorphians, paucituberculatans and diprotodontians, and Epidolops does not share obvious synapomorphies with any marsupial order. Epidolops is dentally specialized, but several morphological features appear to be more plesiomorphic than any crown marsupial. It seems likely Epidolops that falls outside Marsupialia, as do morphologically similar forms such as Bonapartherium and polydolopids. Argyrolagids differ markedly in their known morphology from Epidolops but share some potential apomorphies with paucituberculatans. It is proposed that Polydolopimorphia as currently recognised is polyphyletic, and that argyrolagids (and possibly other taxa currently included in Argyrolagoidea, such as groeberiids and patagoniids) are members of Paucituberculata. This hypothesis is supported by Bayesian non-clock phylogenetic analyses of a total evidence matrix comprising DNA sequence data from five nuclear protein-coding genes, indels, retroposon insertions, and morphological characters: Epidolops falls outside Marsupialia, whereas argyrolagids form a clade with the paucituberculatans Caenolestes and Palaeothentes, regardless of whether the Type II petrosals and IMG VII tarsals are used to score characters for Epidolops or not. There is no clear evidence for the presence of crown marsupials at Itaboraí, and it is possible that the origin and early evolution of Marsupialia was restricted to the "Austral Kingdom" (southern South America, Antarctica, and Australia).


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Article DOI: 10.1007/s10914-016-9357-6

Project DOI: 10.7934/P2436, http://dx.doi.org/10.7934/P2436
This project containsMatrices
  • 1 Media
  • 2 Matrices
  • 2 Documents
  • 42 Taxa
  • 1 Specimen
  • 273 Characters
Total size of project's media files: 6 MB

Download Project SDD File
Total scored cells: 17055
Total media associated with cells: 0
Total labels associated with cell media: 0
Characters
Total characters: 546
Total characters with associated media: 0
Total characters with media with labels: 0
Total character states: 636
Total character states with associated media: 0
Total character states with media with labels:0
Total unordered/ordered characters:444/102
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MorphoBank Project 2436


    Members

    member name taxa specimens media chars character
    media
    labels
    cell scorings
    (scored, NPA, "-")
    cell
    medialabels
    rules
    Robin Beck
    Project Administrator
    Last logged in 12/01/16
    42115460017055
    (16634, 0, 421)
    000


    Taxonomic Overview for Matrix 'M24202' (41 Taxa)

    taxon unscored
    cells
    scored
    cells
    no cell
    support
    NPA
    cells
    "-" cellscell images labels on
    cell images
    member
    access
    [1] Ornithorhynchus
    Last Modified in 09/15/16
    29217215029001
    [2] Tachyglossus
    Last Modified in 09/15/16
    24222220029001
    [3] Vincelestes
    Last Modified in 09/15/16
    79185184010001
    [4] Ukhaatherium
    Last Modified in 09/15/16
    16510710701001
    [5] Asioryctes
    Last Modified in 09/15/16
    15211911902001
    [6] Deltatheridium
    Last Modified in 09/15/16
    176929205001
    [7] Mayulestes
    Last Modified in 09/15/16
    8318818802001
    [8] Pucadelphys
    Last Modified in 09/15/16
    5522021602001
    [9] Andinodelphys
    Last Modified in 09/15/16
    7320019901001
    [10] Didelphis
    Last Modified in 09/15/16
    227926803001
    [11] Monodelphis
    Last Modified in 09/15/16
    327526703001
    [12] Caluromys
    Last Modified in 09/15/16
    8518618404001
    [13] Glironia
    Last Modified in 09/15/16
    8918418202001
    [14] Caenolestes
    Last Modified in 09/15/16
    1126425903001
    [15] Dasyuroides
    Last Modified in 09/15/16
    1226225605001
    [16] Dasyurus
    Last Modified in 09/15/16
    827626302001
    [17] Phascogale
    Last Modified in 09/15/16
    1525925602001
    [18] Notoryctes
    Last Modified in 09/15/16
    44223219010001
    [19] Echymipera
    Last Modified in 09/15/16
    926326004001
    [20] Perameles
    Last Modified in 09/15/16
    427026504001
    [21] Dromiciops
    Last Modified in 09/15/16
    726526303001
    [22] Trichosurus
    Last Modified in 09/15/16
    427326504001
    [23] Phalanger
    Last Modified in 09/15/16
    926725905001
    [24] Petaurus
    Last Modified in 09/15/16
    226926506001
    [25] Pseudochirops
    Last Modified in 09/15/16
    626526205001
    [26] Cercartetus
    Last Modified in 09/15/16
    2424624504001
    [27] Macropus
    Last Modified in 09/15/16
    327026505001
    [28] Dendrolagus
    Last Modified in 09/15/16
    1125925606001
    [29] Dorcopsis
    Last Modified in 09/15/16
    1625325205001
    [30] Thylogale
    Last Modified in 09/15/16
    2024924805001
    [31] Vombatus
    Last Modified in 09/15/16
    9260254010001
    [32] Phascolarctos
    Last Modified in 09/15/16
    1025525508001
    [33] Asiatherium
    Last Modified in 09/15/16
    216585700001
    [34] Herpetotherium
    Last Modified in 09/15/16
    10616616601001
    [35] Peradectidae
    Last Modified in 09/15/16
    175989800001
    [36] Djarthia
    Last Modified in 09/15/16
    179969103001
    [37] Palaeothentes
    Last Modified in 09/15/16
    14512812602001
    [38] Yalkaparidon
    Last Modified in 09/15/16
    14612611809001
    [39] Epidolops
    Last Modified in 09/15/16
    178949401001
    [40] Argyrolagus
    Last Modified in 09/15/16
    16710210006001
    [41] Proargyrolagus
    Last Modified in 09/15/16
    230474300001


    Taxonomic Overview for Matrix 'M24203' (41 Taxa)

    taxon unscored
    cells
    scored
    cells
    no cell
    support
    NPA
    cells
    "-" cellscell images labels on
    cell images
    member
    access
    [1] Ornithorhynchus
    Last Modified in 09/15/16
    29217215029001
    [2] Tachyglossus
    Last Modified in 09/15/16
    24222220029001
    [3] Vincelestes
    Last Modified in 09/15/16
    79185184010001
    [4] Ukhaatherium
    Last Modified in 09/15/16
    16510710701001
    [5] Asioryctes
    Last Modified in 09/15/16
    15211911902001
    [6] Deltatheridium
    Last Modified in 09/15/16
    176929205001
    [7] Mayulestes
    Last Modified in 09/15/16
    8318818802001
    [8] Pucadelphys
    Last Modified in 09/15/16
    5522021602001
    [9] Andinodelphys
    Last Modified in 09/15/16
    7320019901001
    [10] Didelphis
    Last Modified in 09/15/16
    227926803001
    [11] Monodelphis
    Last Modified in 09/15/16
    327526703001
    [12] Caluromys
    Last Modified in 09/15/16
    8518618404001
    [13] Glironia
    Last Modified in 09/15/16
    8918418202001
    [14] Caenolestes
    Last Modified in 09/15/16
    1126425903001
    [15] Dasyuroides
    Last Modified in 09/15/16
    1226225605001
    [16] Dasyurus
    Last Modified in 09/15/16
    827626302001
    [17] Phascogale
    Last Modified in 09/15/16
    1525925602001
    [18] Notoryctes
    Last Modified in 09/15/16
    44223219010001
    [19] Echymipera
    Last Modified in 09/15/16
    926326004001
    [20] Perameles
    Last Modified in 09/15/16
    427026504001
    [21] Dromiciops
    Last Modified in 09/15/16
    726526303001
    [22] Trichosurus
    Last Modified in 09/15/16
    427326504001
    [23] Phalanger
    Last Modified in 09/15/16
    926725905001
    [24] Petaurus
    Last Modified in 09/15/16
    226926506001
    [25] Pseudochirops
    Last Modified in 09/15/16
    626526205001
    [26] Cercartetus
    Last Modified in 09/15/16
    2424624504001
    [27] Macropus
    Last Modified in 09/15/16
    327026505001
    [28] Dendrolagus
    Last Modified in 09/15/16
    1125925606001
    [29] Dorcopsis
    Last Modified in 09/15/16
    1625325205001
    [30] Thylogale
    Last Modified in 09/15/16
    2024924805001
    [31] Vombatus
    Last Modified in 09/15/16
    9260254010001
    [32] Phascolarctos
    Last Modified in 09/15/16
    1025525508001
    [33] Asiatherium
    Last Modified in 09/15/16
    216585700001
    [34] Herpetotherium
    Last Modified in 09/15/16
    10616616601001
    [35] Peradectidae
    Last Modified in 09/15/16
    175989800001
    [36] Djarthia
    Last Modified in 09/15/16
    179969103001
    [37] Palaeothentes
    Last Modified in 09/15/16
    14512812602001
    [38] Yalkaparidon
    Last Modified in 09/15/16
    14612611809001
    [39] Epidolops
    Last Modified in 09/15/16
    219545400001
    [40] Argyrolagus
    Last Modified in 09/15/16
    16710210006001
    [41] Proargyrolagus
    Last Modified in 09/15/16
    230474300001


    Project views

    type number of views Individual items viewed (where applicable)
    Total project views7507
    Project overview1147
    Media views1449Media search (1275 views); M434666 (174 views);
    Matrix views931Matrix landing page (787 views); Morphological matrix B (77 views); Morphological matrix A (67 views);
    Documents list620
    Taxon list2146
    Specimen list610
    Views for media list314
    Bibliography290




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    Total downloads from project105
    Project downloads84
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