Project 3437: Xiaohan Chen, Javier Ortega-Hernández, Joanna M. Wolfe, Dayou Zhai, Xianguang Hou, Ailin Chen, Huijuan Mai, Yu Liu. 2019. The appendicular morphology of Sinoburius lunaris and the evolution of the artiopodan clade Xandarellida (Euarthropoda, early Cambrian) from South China. BMC Evolutionary Biology. 19:165.
Specimen: † Sinoburius lunaris (YKLP/20180012)
View: ventral

Abstract

Background: Artiopodan euarthropods represent common and abundant faunal components in sites with exceptional preservation during the Cambrian. The Chengjiang biota in South China contains numerous taxa that are exclusively known from this deposit, and thus offer a unique perspective on euarthropod diversity during the early Cambrian. One such endemic taxon is the non-trilobite artiopodan Sinoburius lunaris, which has been known for approximately three decades, but few details of its anatomy are well understood due to its rarity within the Chengjiang. Furthermore, the available material does not provide clear information on the ventral organization of this animal, obscuring our understanding of phylogenetically significant details such as the appendages.

Results: We employed X-ray computed tomography to study the non-biomineralized morphology of Sinoburius lunaris. Due to the replacement of the delicate anatomy with pyrite typical of Chengjiang fossils, computed tomography reveals substantial details of the ventral anatomy of Sinoburious lunaris, and allow us to study in detail the three-dimensionally preserved appendicular organization of this taxon for the first time. The dorsal exoskeleton consists of a crescent-shaped head shield will well-developed genal spines, a thorax with seven freely articulating tergites, and a fused pygidium with lateral and median spines. The head bears a pair of ventral stalked eyes that are accommodated by dorsal exoskeletal bulges on the head shield, and an oval elongate ventral hypostome. The appendicular organization of the head is unique among Artiopoda. The deutocerebral antennae are reduced, consisting of only five podomeres, and bear an antennal scale on the second podomere that most likely represents an exite rather than a true ramus. The head includes four post-antennal biramous limb pairs. The first two biramous appendages are differentiated from the rest. The first appendage pair consists of a greatly reduced endopod coupled with a greatly elongated exopod with a potentially sensorial function. The second appendage pair carries a more conventionally sized endopod, but also has an enlarged exopod. The remaining biramous appendages are homonomous in their construction, but decrease in size towards the posterior end of the body. They consist of a basipodite with ridge-like crescentic endites, an endopod with seven podomeres and a terminal claw, and a lamellae-bearing exopod with a slender shaft. Contrary to previous reports, we confirm the presence of segmental mismatch in Sinoburius lunaris, expressed as diplotergites in the thorax. Maximum parsimony and Bayesian phylogenetic analyses support the monophyly of Xandarellida within Artiopoda, and illuminate the internal relationships within this enigmatic clade. Our results allow us to propose a transformation series explaining the origin of archetypical xandarellid characters, such as the evolution of eye slits in Xandarella spectaculum and Phytophilaspis pergamena as derivates from the anterolateral notches in the head shield observed in Cindarella eucalla and Luohuilinella species. In this context, Sinoburius lunaris is found to feature several derived characters within the group, such as the loss of eye slits and a high degree of appendicular tagmosis.

Conclusions:
The revised morphology of Sinoburius lunaris, made possible through the use of computed tomography to resolve details of its three-dimensionally preserved appendicular anatomy, contributes to an improved understanding of the morphology of this taxon and the evolution of Xandarellida more broadly. Our results indicate that Sinoburius lunaris possesses an unprecedented degree of appendicular tagmosis otherwise unknown within Artiopoda, with the implication that this iconic group of Palaeozoic euarthropods likely had a more complex ecology and functional morphology than previously considered. The application of computer tomographic techniques to the study of Chengjiang euarthropods holds exceptional promise to better understand the morphological diversity of these organisms, and reconstruct their evolutionary relationships and history.



Read the article »

Article DOI: 10.1186/s12862-019-1491-3

Project DOI: 10.7934/P3437, http://dx.doi.org/10.7934/P3437
This project containsMatrices
  • 1 Media
  • 1 Matrix
  • 64 Taxa
  • 1 Specimen
  • 89 Characters
Total size of project's media files: 5 MB

Download Project SDD File
Total scored cells: 4707
Total media associated with cells: 0
Total labels associated with cell media: 0
Characters
Total characters: 89
Total characters with associated media: 0
Total characters with media with labels: 0
Total character states: 205
Total character states with associated media: 0
Total character states with media with labels:0
Total unordered/ordered characters:89/0
Currently Viewing:
MorphoBank Project 3437


    Members

    member name taxa specimens media media
    notes
    chars character
    comms
       
    notes  media
    labels
    cell scorings
    (scored, NPA, "-")
    cell
    comms
        
    notes  medialabels
    rules
    Jo Wolfe
    Project Administrator
    Last logged in 08/06/19
    641108900004707
    (3619, 0, 1088)
    00000
    Javier Ortega-Hernández
    Full membership
    Last logged in Never
    0000000000
    (0, 0, 0)
    00000


    Taxonomic Overview for Matrix 'M25978' (64 Taxa)

    taxon unscored
    cells
    scored
    cells
    no cell
    support
    NPA
    cells
    "-" cellscell images labels on
    cell images
    member
    access
    [1] † Fortiforceps foliosa
    Last Modified in 04/02/19
    16969019002
    [2] † Aglaspella granulifera
    Last Modified in 04/02/19
    215858010002
    [3] † Aglaspis spinifer
    Last Modified in 04/02/19
    166363010002
    [4] † Alalcomenaeus cambricus
    Last Modified in 04/02/19
    06969020002
    [5] † Australaglaspis stonyensis
    Last Modified in 04/02/19
    275252010002
    [6] † Beckwithia typa
    Last Modified in 04/02/19
    295050010002
    [7] † Brachyaglaspis singularis
    Last Modified in 04/02/19
    334141015002
    [8] † Buenaspis
    Last Modified in 04/02/19
    254747017002
    [9] † Burgessia bella
    Last Modified in 04/02/19
    06060029002
    [10] † Cheloniellon calmani
    Last Modified in 04/02/19
    46969016002
    [11] † Chlupacaris dubia
    Last Modified in 04/02/19
    374242010002
    [12] † Chraspedops
    Last Modified in 04/02/19
    294949011002
    [13] † Cindarella eucalla
    Last Modified in 04/02/19
    07171018002
    [14] † Cyclopites vulgaris
    Last Modified in 04/02/19
    245555010002
    [15] † Duslia insignis
    Last Modified in 04/02/19
    265050013002
    [16] † Emeraldella brockii
    Last Modified in 04/02/19
    06969020002
    [17] † Eoredlichia intermedia
    Last Modified in 04/02/19
    07373016002
    [18] † Eozetetes gemelli
    Last Modified in 04/02/19
    285050011002
    [19] † Flobertia kochi
    Last Modified in 04/02/19
    42434304002
    [20] † Glypharthrus magnoculus
    Last Modified in 04/02/19
    334646010002
    [21] † Glypharthrus simplex
    Last Modified in 04/02/19
    215757011002
    [22] † Glypharthrus thomasi
    Last Modified in 04/02/19
    314848010002
    [23] † Glypharthrus trispinicaudatus
    Last Modified in 04/02/19
    32484809002
    [24] † Gogglops
    Last Modified in 04/02/19
    33474709002
    [25] † Haikoucaris
    Last Modified in 04/02/19
    06969020002
    [26] † Helmetia expansa
    Last Modified in 04/02/19
    195353017002
    [27] † Kodymirus vagans
    Last Modified in 04/02/19
    106463016002
    [28] † Kuamaia
    Last Modified in 04/02/19
    46666019002
    [29] † Kwanyinaspis maotiashanensis
    Last Modified in 04/02/19
    146363012002
    [30] † Leanchoilia superlata
    Last Modified in 04/02/19
    26666021002
    [31] † Liwia convexa
    Last Modified in 04/02/19
    195151019002
    [32] † Marrella splendens
    Last Modified in 04/02/19
    25555032002
    [33] † Martinssonia elongata
    Last Modified in 04/02/19
    05757032002
    [34] † Mimetaster hexagonalis
    Last Modified in 04/02/19
    16262026002
    [35] † Misszhouia longicaudata
    Last Modified in 04/02/19
    16666022002
    [36] † Naraoia compacta
    Last Modified in 04/02/19
    16766022002
    [37] † Naraoia spinosa
    Last Modified in 04/02/19
    16666022002
    [38] Nebalia bipes
    Last Modified in 04/02/19
    06262027002
    [39] † Neostrabops
    Last Modified in 04/02/19
    40424207002
    [40] † Olenoides serratus
    Last Modified in 04/02/19
    07272017002
    [41] † Phytophilaspis pergamena
    Last Modified in 04/02/19
    235151015002
    [42] † Quasimodaspis brentsae
    Last Modified in 04/02/19
    304949010002
    [43] † Rebachiella kinnekullensis
    Last Modified in 04/02/19
    06262027002
    [44] † Retifacies abnormalis
    Last Modified in 04/02/19
    17070018002
    [45] † Saperion
    Last Modified in 04/02/19
    56060024002
    [46] † Sidneyia inexpectans
    Last Modified in 04/02/19
    07474015002
    [47] † Sinoburius lunaris
    Last Modified in 04/02/19
    17171017002
    [48] † Skioldia
    Last Modified in 04/02/19
    105555024002
    [49] † Soomaspis
    Last Modified in 04/02/19
    254747017002
    [50] † Squamacula clypeata
    Last Modified in 04/02/19
    06060029002
    [51] † Tariccoia
    Last Modified in 04/02/19
    254747017002
    [52] † Tegopelte gigas
    Last Modified in 04/02/19
    155050024002
    [53] † Tremaglaspis unite
    Last Modified in 04/02/19
    234848018002
    [54] † Tremaglaspis vanroyi
    Last Modified in 04/02/19
    314242016002
    [55] † Triopus draboviensis morocco
    Last Modified in 04/02/19
    284848013002
    [56] † Uarthrus instabilis
    Last Modified in 04/02/19
    28525209002
    [57] † Xandarella spectacullum
    Last Modified in 04/02/19
    07272017002
    [58] † Acanthomeridion anacanthus
    Last Modified in 04/02/19
    224747020002
    [59] † Acanthomeridion serratum
    Last Modified in 04/02/19
    224747020002
    [60] † Australimicola spriggi
    Last Modified in 04/02/19
    165050023002
    [61] † Zhiwenia coronata
    Last Modified in 04/02/19
    125858019002
    [62] † Luohuilinella rarus
    Last Modified in 04/02/19
    393939011002
    [63] † Luohuilinella deletres
    Last Modified in 04/02/19
    66464019002
    [64] † Haifengella corona
    Last Modified in 04/02/19
    234949017002


    Project views

    type number of views Individual items viewed (where applicable)
    Total project views195
    Project overview76
    Media views31Media search (26 views); M662034 (5 views);
    Matrix views19Matrix landing page (15 views); Artiopoda matrix (4 views);
    Views for media list6
    Specimen list10
    Taxon list50
    Bibliography3




    Project downloads

    type number of downloads Individual items downloaded (where applicable)
    Total downloads from project8
    Project downloads4
    Matrix downloads4Artiopoda matrix (4 downloads);