Project 724: J. C. Lamsdell. 2013. Revised systematics of Palaeozoic ‘horseshoe crabs’ and the myth of monophyletic Xiphosura. Zoological Journal of the Linnean Society. 167:1–27.
Specimen: Limulus polyphemus (unvouchered)

Abstract

The monophyly of the class Xiphosura is critically re-examined. For the first time a phylogenetic analysis of a number of synziphosurine and xiphosurid taxa is performed together with representatives of the other chelicerate Orders also included as ingroup taxa. Xiphosura as currently defined is shown to be paraphyletic, and a revised classification is presented. Previous characteristics used to unite the xiphosurids (possessing a fused thoracetron) and a paraphyletic grade of synziphosurines (retaining freely articulating opisthosomal tergites) include the presence of a cardiac lobe, ophthalmic ridges, an axial region of the opisthosoma and a reduced first opisthosomal segment. All of these characteristics are however here shown to be present in other chelicerate groups, leaving Xiphosura without any defining synapomorphies. A number of other characters, including the form of the chelicerae and appendage VII, indicate that xiphosurans may be paraphyletic with respect to a clade consisting of chasmataspidids, eurypterids, and arachnids. What ramifications this has for the evolution of basal chelicerates is briefly discussed, and it is recognised that most of the currently known ‘synziphosurine’ taxa represent offshoots from the main chelicerate lineage with ghost ranges extending into at least the Middle Ordovician.


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Project DOI: 10.7934/P724, http://dx.doi.org/10.7934/P724
This project containsMatrices
  • 1 Media
  • 1 Matrix
  • 37 Taxa
  • 1 Specimen
  • 114 Characters
Total size of project's media files: 3 MB

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Total scored cells: 3042
Total media associated with cells: 0
Total labels associated with cell media: 0
Characters
Total characters: 114
Total characters with associated media: 0
Total characters with media with labels: 0
Total character states: 295
Total character states with associated media: 0
Total character states with media with labels:0
Total unordered/ordered characters:114/0
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MorphoBank Project 724


    Members

    member name taxa specimens media chars character
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    (scored, NPA, "-")
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    James Lamsdell
    Project Administrator
    Last logged in 01/10/13
    3711114003042
    (2668, 0, 374)
    000


    Taxonomic Overview for Matrix 'M1800' (37 Taxa)

    taxon unscored
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    [1] Fuxianhuia protensa
    Last Modified in 12/05/13
    97878027001
    [2] Leanchoilia illecebrosa
    Last Modified in 12/05/13
    178787010001
    [3] Alalcomenaeus cambricus
    Last Modified in 12/05/13
    99595010001
    [4] Yohoia tenuis
    Last Modified in 12/05/13
    277676011001
    [5] Emeraldella brocki
    Last Modified in 12/05/13
    118888015001
    [6] Sydneyia inexpectans
    Last Modified in 12/05/13
    158686013001
    [7] Olenoides serratus
    Last Modified in 12/05/13
    2100100012001
    [8] Pycnogonum litorale
    Last Modified in 12/05/13
    35959052001
    [9] Haliestes dasos
    Last Modified in 12/05/13
    135252049001
    [10] Palaeoisopus problematicus
    Last Modified in 12/05/13
    76161046001
    [11] Offacolus kingi
    Last Modified in 12/05/13
    38717105001
    [12] Weinbergina opitzi
    Last Modified in 12/05/13
    29848401001
    [13] Camanchia grovensis
    Last Modified in 12/05/13
    62505002001
    [14] Venustulus waukeshaensis
    Last Modified in 12/05/13
    53595902001
    [15] Willwerathia laticeps
    Last Modified in 12/05/13
    62525200001
    [16] Lunataspis aurora
    Last Modified in 12/05/13
    64474703001
    [17] Limulus polyphemus
    Last Modified in 12/05/13
    010610608001
    [18] Paleolimulus signatus
    Last Modified in 12/05/13
    24858505001
    [19] Stoermeropterus conicus
    Last Modified in 12/05/13
    1010010004001
    [20] Eurypterus tetragonophthalmus
    Last Modified in 12/05/13
    110510508001
    [21] Rhenopterus diensti
    Last Modified in 12/05/13
    810310303001
    [22] Parastylonurus ornatus
    Last Modified in 12/05/13
    14979703001
    [23] Chasmataspis laurencii
    Last Modified in 12/05/13
    51595904001
    [24] Octoberaspis ushakovi
    Last Modified in 12/05/13
    33757506001
    [25] Centruroides vittatus
    Last Modified in 12/05/13
    19898015001
    [26] Palaeophonus nuncius
    Last Modified in 12/05/13
    237777014001
    [27] Mastigoproctus giganteus
    Last Modified in 12/05/13
    49393017001
    [28] Galeodes armeniacus
    Last Modified in 12/05/13
    138280021001
    [29] Euproops anthrax
    Last Modified in 12/05/13
    38707006001
    [30] Legrandella lombardi
    Last Modified in 12/05/13
    57575700001
    [31] Bembicosoma pomphicus
    Last Modified in 12/05/13
    71434300001
    [32] Bunodes lunula
    Last Modified in 12/05/13
    69434302001
    [33] Limuloides limuloides
    Last Modified in 12/05/13
    66484800001
    [34] Pasternakevia podolica
    Last Modified in 12/05/13
    70444400001
    [35] Cyamocephalus loganensis
    Last Modified in 12/05/13
    67474700001
    [36] Pseudoniscus roosevelti
    Last Modified in 12/05/13
    70444400001
    [37] Kasibelinurus amoricum
    Last Modified in 12/05/13
    67474700001


    Project views

    type number of views Individual items viewed (where applicable)
    Total project views19329
    Project overview2719
    Media views4083Media search (3580 views); M108682 (503 views);
    Matrix views1881Matrix landing page (1676 views); Xiphosuran analysis (205 views);
    Specimen list1906
    Taxon list8740




    Project downloads

    type number of downloads Individual items downloaded (where applicable)
    Total downloads from project194
    Matrix downloads12Xiphosuran analysis (12 downloads);
    Project downloads182