Project 3938: B. M. Wynd, S. J. Nesbitt, M. R. Stocker, A. B. Heckert. 2019. A Detailed description of Rugarhynchos sixmilensis, gen. et comb. nov. (Archosauriformes, Proterochampsia), and cranial convergence in snout elongation across stem and crown archosaurs. Journal of Vertebrate Paleontology. 39 (6):e1748042.
Specimen: † Rugarhynchos sixmilensis (unvouchered)
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Abstract

The Triassic Period (252–201.5 Ma) records a great expansion of saurian diversity and disparity, particularly in skull morphology. Stem archosaurs exhibit substantial cranial disparity, especially by taxa either shortening or elongating the skull. This disparity is exemplified in the North American Late Triassic proterochampsians by the ‘short-faced’ Vancleavea and the ‘long-faced’ doswelliids. To critically investigate skull elongation and character evolution in these proterochampsians, we evaluate ‘Doswellia’ sixmilensis, known from much of a skull, cervical centra, and osteoderms from the Bluewater Creek Member of the Chinle Formation of New Mexico. We redescribe the holotype based on extensive repreparation of the holotype material, resulting in the identification of the orbit and clarifying the extent of related bones. As such, the diagnosis of the taxon is substantially modified and a new genus, Rugarhynchos, gen. nov., is erected. Rugarhynchos sixmilensis, gen. et comb. nov., exhibits an elongate snout with characteristics known in stem and crown archosaurs, including a downturned premaxilla and fluted teeth. We included R. sixmilensis in a phylogenetic analysis of archosauromorphs consisting of 677 characters and 109 taxa under both parsimony and Bayesian models. We recover R. sixmilensis as a doswelliid, sister to Doswellia kaltenbachi. Our parsimony and Bayesian models differ in the placement of Doswelliidae, either as sister to or within Proterochampsidae, respectively. We use archosauromorph relationships from the Bayesian model to estimate cranial disparity between stem and crown archosaurs and find a narrow breadth of morphological disparity in the stem. Our results suggest that crown archosaurs evolved disparate crania from a low-disparate archosauriform condition.


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Article DOI: 10.1080/02724634.2019.1748042

Project DOI: 10.7934/P3938, http://dx.doi.org/10.7934/P3938
This project containsMatrices
  • 1 Media
  • 1 Matrix
  • 1 Document
  • 119 Taxa
  • 1 Specimen
  • 677 Characters
Total size of project's media files: 253.79k

Download Project SDD File
Total scored cells: 38756
Total media associated with cells: 0
Total labels associated with cell media: 0
Characters
Total characters: 677
Total characters with associated media: 0
Total characters with media with labels: 0
Total character states: 1572
Total character states with associated media: 0
Total character states with media with labels:0
Total unordered/ordered characters:573/104
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MorphoBank Project 3938
  • Creation Date:
    22 February 2021
  • Publication Date:
    26 October 2021
  • Project views: 408

    Authors' Institutions

    • Appalachian State University

    • Virginia Tech (Virginia Polytechnic Institute and State University)



    Members

    member name taxa specimens media chars character
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    Taxonomic Overview for Matrix 'M27694' (119 Taxa)

    taxon unscored
    cells
    scored
    cells
    no cell
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    NPA
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    [1] † Petrolacosaurus kansensis
    Last Modified in 10/26/21
    7352650808000none
    [2] † Acerosodontosaurus piveteaui
    Last Modified in 10/26/21
    44318818204600none
    [3] † Youngina capensis
    Last Modified in 10/26/21
    6754750006800none
    [4] † Paliguana whitei
    Last Modified in 10/26/21
    568888602100none
    [5] † Planocephalosaurus robinsonae
    Last Modified in 10/26/21
    21339338107200none
    [6] † Gephyrosaurus bridensis
    Last Modified in 10/26/21
    18643640905900none
    [7] † Cteniogenys sp.
    Last Modified in 10/26/21
    36427626904200none
    [8] † Simoedosaurus lemoinei
    Last Modified in 10/26/21
    13348548006300none
    [9] † Aenigmastropheus parringtoni
    Last Modified in 10/26/21
    64038360000none
    [10] † Protorosaurus speneri
    Last Modified in 10/26/21
    17545240406300none
    [11] † Amotosaurus rotfeldensis
    Last Modified in 10/26/21
    34329228504700none
    [12] † Macrocnemus bassanii
    Last Modified in 10/26/21
    21840036806300none
    [13] † Tanystropheus longobardicus
    Last Modified in 10/26/21
    7453347708500none
    [14] † Jesairosaurus lehmani
    Last Modified in 10/26/21
    32130428706300none
    [15] † Pamelaria dolichotrachela
    Last Modified in 10/26/21
    14348748205200none
    [16] † Azendohsaurus madagaskarensis
    Last Modified in 10/26/21
    5756855805700none
    [17] † Trilophosaurus buettneri
    Last Modified in 10/26/21
    7952749407600none
    [18] † Noteosuchus colletti
    Last Modified in 10/26/21
    50216315101500none
    [19] † Mesosuchus browni
    Last Modified in 10/26/21
    7055452305500none
    [20] † Howesia browni
    Last Modified in 10/26/21
    30234932203200none
    [21] † Eohyosaurus wolvaardti
    Last Modified in 10/26/21
    52514313701400none
    [22] † Rhynchosaurus articeps
    Last Modified in 10/26/21
    16246344905500none
    [23] † Bentonyx sidensis
    Last Modified in 10/26/21
    42621421303800none
    [24] † Mesodapedon kuttyi
    Last Modified in 10/26/21
    64331310300none
    [25] † Ammorhynchus navajoi
    Last Modified in 10/26/21
    622414001500none
    [26] † Stenaulorhynchus stockleyi
    Last Modified in 10/26/21
    11351150905500none
    [27] † Brasinorhynchus mariantensis
    Last Modified in 10/26/21
    39125425203400none
    [28] † Chanares rhynchosaur
    Last Modified in 10/26/21
    63840370200none
    [29] † Langeronyx brodiei
    Last Modified in 10/26/21
    52912212102700none
    [30] † Fodonyx spenceri
    Last Modified in 10/26/21
    54312112101300none
    [31] † Isalorhynchus genovefae
    Last Modified in 10/26/21
    18544544104900none
    [32] † Eorasaurus olsoni
    Last Modified in 10/26/21
    65227240000none
    [33] † Prolacertoides jimusarensis
    Last Modified in 10/26/21
    591656302200none
    [34] † Prolacerta broomi
    Last Modified in 10/26/21
    3060455805600none
    [35] † K australiensis combined
    Last Modified in 10/26/21
    559989302500none
    [36] † Boreopricea funerea
    Last Modified in 10/26/21
    36628025203900none
    [37] † Archosaurus rossicus holotype
    Last Modified in 10/26/21
    65819180000none
    [38] † Proterosuchus fergusi
    Last Modified in 10/26/21
    14751149603200none
    [39] † Proterosuchus goweri
    Last Modified in 10/26/21
    41824924501400none
    [40] † Proterosuchus alexanderi
    Last Modified in 10/26/21
    19145545103400none
    [41] † "Chasmatosaurus" yuani
    Last Modified in 10/26/21
    15449548104100none
    [42] † Tasmaniosaurus triassicus
    Last Modified in 10/26/21
    5701029501200none
    [43] † Vonhuenia fredericki
    Last Modified in 10/26/21
    65718180200none
    [44] † C rossicus combined
    Last Modified in 10/26/21
    63541400200none
    [45] † C magnus combined
    Last Modified in 10/26/21
    65125250100none
    [46] † Chasmatosuchus vjushkovi
    Last Modified in 10/26/21
    65722200000none
    [47] † Koilamasuchus gonzalezdiazi
    Last Modified in 10/26/21
    64731280200none
    [48] † Kalisuchus rewanensis holotype
    Last Modified in 10/26/21
    634383301000none
    [49] † Fugusuchus hejiapanensis
    Last Modified in 10/26/21
    46319719401900none
    [50] † Sarmatosuchus otschevi
    Last Modified in 10/26/21
    4462312240700none
    [51] † Guchengosuchus shiguaiensis
    Last Modified in 10/26/21
    48217717002500none
    [52] † Cuyosuchus huenei
    Last Modified in 10/26/21
    4931881780600none
    [53] † Garjainia prima
    Last Modified in 10/26/21
    10953753203500none
    [54] † Garjainia madiba combined
    Last Modified in 10/26/21
    35132030401600none
    [55] † Erythrosuchus africanus
    Last Modified in 10/26/21
    6357656504200none
    [56] † Shansisuchus shansisuchus
    Last Modified in 10/26/21
    16547747104000none
    [57] † Shansisuchus kuyeheensis
    Last Modified in 10/26/21
    592807501000none
    [58] † Chalishevia cothurnata
    Last Modified in 10/26/21
    583868401000none
    [59] † Youngosuchus sinensis
    Last Modified in 10/26/21
    35431130401900none
    [60] † Uralosaurus combined
    Last Modified in 10/26/21
    64526260600none
    [61] † Vancleavea campi
    Last Modified in 10/26/21
    20941541005600none
    [62] † Asperoris mnyama
    Last Modified in 10/26/21
    5661018901600none
    [63] † Euparkeria capensis
    Last Modified in 10/26/21
    4162261002600none
    [64] † Dorosuchus neoetus
    Last Modified in 10/26/21
    5761001000100none
    [65] † Yarasuchus deccanensis
    Last Modified in 10/26/21
    4841861830900none
    [66] † Dongusuchus efremovi
    Last Modified in 10/26/21
    64631310000none
    [67] † Teleocrater rhadinus
    Last Modified in 10/26/21
    40625525401700none
    [68] † Spondylosoma absconditum
    Last Modified in 10/26/21
    60966650300none
    [69] † Proterochampsa barrionuevoi
    Last Modified in 10/26/21
    19743943104900none
    [70] † Proterochampsa nodosa
    Last Modified in 10/26/21
    45920219601700none
    [71] † Tropidosuchus romeri
    Last Modified in 10/26/21
    15949748703000none
    [72] † Cerritosaurus binsfeldi
    Last Modified in 10/26/21
    45320820302100none
    [73] † Gualosuchus reigi
    Last Modified in 10/26/21
    19745244203600none
    [74] † Chanaresuchus bonapartei
    Last Modified in 10/26/21
    6857756304200none
    [75] † Pseudochampsa ischigualastensis
    Last Modified in 10/26/21
    27737837202800none
    [76] † Rhadinosuchus gracilis
    Last Modified in 10/26/21
    5701019501200none
    [77] † Archeopelta arborensis
    Last Modified in 10/26/21
    5751011010100none
    [78] † Tarjadia ruthae
    Last Modified in 10/26/21
    22942842402400none
    [79] † Erpetosuchus granti
    Last Modified in 10/26/21
    36229328902400none
    [80] † Erpetosuchus sp
    Last Modified in 10/26/21
    58984790900none
    [81] † Dyoplax arenaceus
    Last Modified in 10/26/21
    62849470200none
    [82] † Jaxtasuchus salomoni
    Last Modified in 10/26/21
    48718217501500none
    [83] † Doswellia kaltenbachi
    Last Modified in 10/26/21
    30932732104700none
    [84] † Parasuchus angustifrons
    Last Modified in 10/26/21
    42522322003200none
    [85] † Parasuchus hislopi
    Last Modified in 10/26/21
    8756055403400none
    [86] † Nicrosaurus kapffi
    Last Modified in 10/26/21
    22242241304000none
    [87] † Smilosuchus spp.
    Last Modified in 10/26/21
    8455354304500none
    [88] † Diandongosuchus fuyuanensis
    Last Modified in 10/26/21
    28237737502000none
    [89] † Ornithosuchus woodwardi
    Last Modified in 10/26/21
    20744643902700none
    [90] † Riojasuchus tenuisceps
    Last Modified in 10/26/21
    9455654403300none
    [91] † Venaticosuchus rusconii
    Last Modified in 10/26/21
    51015215001700none
    [92] † Nundasuchus songeaensis
    Last Modified in 10/26/21
    4352352330900none
    [93] † Turfanosuchus dabanensis
    Last Modified in 10/26/21
    20944944202400none
    [94] † Gracilisuchus stipanicicorum
    Last Modified in 10/26/21
    13651950703400none
    [95] † Yonghesuchus sangbiensis
    Last Modified in 10/26/21
    49616616301800none
    [96] † Parringtonia gracilis
    Last Modified in 10/26/21
    591817601000none
    [97] † Aetosauroides scagliai
    Last Modified in 10/26/21
    26140639102400none
    [98] † Aetosaurus ferratus
    Last Modified in 10/26/21
    15749649102900none
    [99] † Stagonolepis robertsoni
    Last Modified in 10/26/21
    5359459303100none
    [100] † Ticinosuchus ferox
    Last Modified in 10/26/21
    40426225701600none
    [101] † Qianosuchus mixtus
    Last Modified in 10/26/21
    25539739502700none
    [102] † Arizonasaurus babbitti
    Last Modified in 10/26/21
    30434433903400none
    [103] † Lotosaurus adentus
    Last Modified in 10/26/21
    25736836205800none
    [104] † Xilousuchus sapingensis
    Last Modified in 10/26/21
    48018118001600none
    [105] † Luperosuchus fractus
    Last Modified in 10/26/21
    5671101080200none
    [106] † Decuriasuchus quartacolonia
    Last Modified in 10/26/21
    30734634202800none
    [107] † Batrachotomus kupferzellensis
    Last Modified in 10/26/21
    12352952003000none
    [108] † Prestosuchus chiniquensis
    Last Modified in 10/26/21
    6758558003000none
    [109] † Scleromochlus taylori
    Last Modified in 10/26/21
    51015013902800none
    [110] † Dimorphodon macronyx
    Last Modified in 10/26/21
    31631130605500none
    [111] † Lagerpeton chanarensis
    Last Modified in 10/26/21
    52014113701800none
    [112] † Marasuchus lilloensis
    Last Modified in 10/26/21
    33531831203000none
    [113] † Asilisaurus kongwe
    Last Modified in 10/26/21
    44721521301700none
    [114] † Lewisuchus admixtus
    Last Modified in 10/26/21
    38327726902300none
    [115] † Silesaurus opolensis
    Last Modified in 10/26/21
    12351450404900none
    [116] † Heterodontosaurus tucki
    Last Modified in 10/26/21
    6953552907500none
    [117] † Herrerasaurus ischigualastensis
    Last Modified in 10/26/21
    6357456205200none
    [118] † Rugarhynchos sixmilensis
    Last Modified in 10/26/21
    48814614304600none
    [119] † Litorusuchus somnii
    Last Modified in 10/26/21
    27338437802600none


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