Project 198: S. J. Nesbitt. 2011. The Early Evolution of Archosaurs: Relationships and the Origin of Major Clades. Bulletin of the American Museum of Natural History. 352:1-292.
Specimen: † Postosuchus kirkpatricki (TTU/P:9000)
View: lateral

Abstract

Archosaurs have a nearly 250 million year record that originated shortly after the Permian-Triassic extinction event and is continued today by two extant clades, the crocodylians and the avians. The two extant lineages exemplify two bauplan extremes among a diverse and complex evolutionary history, but little is known about the common ancestor of these lineages. Renewed interest in early archosaurs has led to nearly a doubling of the known taxa in the last
20 years. This study presents a thorough phylogenetic analysis of 80 species-level taxa ranging from the latest Permian to the early part of the Jurassic using a dataset of 412 characters. Each terminal taxon is explicitly described and all specimens used in the analysis are clearly stated.Additionally, each character is discussed in detail and nearly all of the character states are illustrated in either a drawing or highlighted on a specimen photograph. A combination of novel characters and comprehensive character sampling has bridged previously published analyses that focus on particular archosauriform subclades.
A well-resolved, robustly supported consensus tree (MPTs 360) found a monophyletic Archosauria consisting of two major branches, the crocodylian-line and avian-line lineages. The monophyly of clades such as Ornithosuchidae, Phytosauria, Aetosauria, Crocodylomorpha, and Dinosauria is supported in this analysis. However, phytosaurs are recovered as the closest sister taxon to Archosauria, rather than basal crocodylian-line archosaurs, for the first time. Among taxa classically termed as ‘‘rauisuchians,’’ a monophyletic poposauroid clade was found as the sister taxon to a group of paraphyletic ‘‘rauisuchians’’ and monophyletic crocodylomorphs. Hence, crocodylomorphs are well nested within a clade of ‘‘rauisuchians,’’ and are not more closely related to aetosaurs than to taxa such as Postosuchus. Basal crocodylomorphs such as Hesperosuchus and similar forms (‘‘Sphenosuchia’’) were found as a paraphyletic grade leading to the clade Crocodyliformes. Among avian-line archosaurs, Dinosauria is well supported. A monophyletic clade containing Silesaurus and similar forms is well supported as the sister taxon to Dinosauria. Pterosaurs are robustly supported at the base of the avian line.
A time-calibrated phylogeny of Archosauriformes indicates that the origin and initial diversification of Archosauria occurred during the Early Triassic following the Permian-Triassic extinction. Furthermore, all major basal archosaur lineages except Crocodylomorpha were established by the end of the Anisian. Early archosaur evolution is characterized by high rates of homoplasy, long ghost lineages, and high rates of character evolution. These data imply that much of the early history of Archosauria has not been recovered from the fossil record. Not only were archosaurs diverse by the Middle Triassic, but they had nearly a cosmopolitan biogeographic distribution by the end of the Anisian.


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Project DOI: 10.7934/P198, http://dx.doi.org/10.7934/P198
This project containsMatrices
  • 1 Media
  • 1 Matrix
  • 1 Document
  • 151 Taxa
  • 1 Specimen
  • 412 Characters


Download Project SDD File
Total scored cells: 29317
Total media associated with cells: 0
Total labels associated with cell media: 0
Characters
Total characters: 412
Total characters with associated media: 0
Total characters with media with labels: 0
Total character states: 895
Total character states with associated media: 0
Total character states with media with labels:0
Total unordered/ordered characters:412/0
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MorphoBank Project 198

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    member name taxa specimens media chars character
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    Sterling Nesbitt
    Project Administrator
    Last logged in 11/08/11
    151004120029317
    (20455, 7745, 1117)
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    MorphoBank Curator
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    Last logged in 08/07/14
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    Randall Irmis
    Full membership
    Last logged in 01/19/11
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    000
    Mark Norell
    Full membership
    Last logged in Never
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    Taxonomic Overview for Matrix 'M559' (83 Taxa)

    taxon unscored
    cells
    scored
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    no cell
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    cell images
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    [1] † Mesosuchus browni
    Last Modified in 12/05/13
    213303301447004
    [2] † Prolacerta broomi
    Last Modified in 12/05/13
    9358356441004
    [3] † Archosaurus rossicus
    Last Modified in 12/05/13
    4075500004
    [4] † Proterosuchus fergusi
    Last Modified in 12/05/13
    43633601530004
    [5] † Erythrosuchus africanus
    Last Modified in 12/05/13
    73623622023004
    [6] † Vancleavea campi
    Last Modified in 12/05/13
    102281281524004
    [7] † Chanaresuchus bonapartei
    Last Modified in 12/05/13
    153593592612004
    [8] † Tropidosuchus romeri
    Last Modified in 12/05/13
    353103105314004
    [9] † Euparkeria capensis
    Last Modified in 12/05/13
    639539439004
    [10] † Parasuchus hislopi
    Last Modified in 12/05/13
    53346346112004
    [11] † Smilosuchus gregorii
    Last Modified in 12/05/13
    323373372914004
    [12] † Pseudopalatus pristinus
    Last Modified in 12/05/13
    18381381112004
    [13] † Gracilisuchus stipanicicorum
    Last Modified in 12/05/13
    27302302749004
    [14] † Turfanosuchus dabanensis
    Last Modified in 12/05/13
    222602581237004
    [15] † Ornithosuchus longidens
    Last Modified in 12/05/13
    80272272537004
    [16] † Riojasuchus tenuisceps
    Last Modified in 12/05/13
    27351351259004
    [17] † Revueltosaurus callenderi
    Last Modified in 12/05/13
    3936636616004
    [18] † Stagonolepis robertsoni
    Last Modified in 12/05/13
    9431231124004
    [19] † Aetosaurus ferratus
    Last Modified in 12/05/13
    115265264312004
    [20] † Longosuchus meadei
    Last Modified in 12/05/13
    5634333267004
    [21] † Ticinosuchus ferox
    Last Modified in 12/05/13
    196201196114004
    [22] † Qianosuchus mixtus
    Last Modified in 12/05/13
    99281281293004
    [23] † Xilousuchus sapingensis
    Last Modified in 12/05/13
    71171162880004
    [24] † Arizonasaurus babbitti
    Last Modified in 12/05/13
    2425225012412004
    [25] † Poposaurus gracilis holotype
    Last Modified in 12/05/13
    938373641004
    [26] † Poposaurus gracilis yale
    Last Modified in 12/05/13
    2221320716414004
    [27] † Lotosaurus adentus
    Last Modified in 12/05/13
    403093093330004
    [28] † Sillosuchus longicervix
    Last Modified in 12/05/13
    47787827710004
    [29] † Effigia okeeffeae
    Last Modified in 12/05/13
    433143142629004
    [30] † Shuvosaurus inexpectatus
    Last Modified in 12/05/13
    443073073229004
    [31] † Prestosuchus chiniquensis
    Last Modified in 12/05/13
    211691692202004
    [32] † UFRGS 0156-T
    Last Modified in 12/05/13
    421661662022004
    [33] † UFRGS 152-T
    Last Modified in 12/05/13
    352642641103004
    [34] Combined Prestosuchus
    Last Modified in 12/05/13
    5435235224004
    [35] † Saurosuchus galilei
    Last Modified in 12/05/13
    48308303542004
    [36] † Batrachotomus kuperferzellensis
    Last Modified in 12/05/13
    7349345551004
    [37] † Fasolasuchus tenax
    Last Modified in 12/05/13
    41611612452004
    [38] † Rauisuchus triradentes
    Last Modified in 12/05/13
    171321322630004
    [39] † Polonosuchus silesiacus
    Last Modified in 12/05/13
    71181182870004
    [40] † Postosuchus kirkpatricki
    Last Modified in 12/05/13
    37336336354004
    [41] † Postosuchus alisonae
    Last Modified in 12/05/13
    91681672332004
    [42] † CM 73372
    Last Modified in 12/05/13
    531611601944004
    [43] † Hesperosuchus agilis
    Last Modified in 12/05/13
    102142131853004
    [44] † Dromicosuchus grallator
    Last Modified in 12/05/13
    72269268674004
    [45] † Hesperosuchus "agilis"
    Last Modified in 12/05/13
    192882881005004
    [46] † Dibothrosuchus elaphros
    Last Modified in 12/05/13
    160217217296004
    [47] † Terrestrisuchus gracilis
    Last Modified in 12/05/13
    63316316258004
    [48] † Sphenosuchus acutus
    Last Modified in 12/05/13
    132152141795004
    [49] † Litargosuchus leptorhynchus
    Last Modified in 12/05/13
    121891882083004
    [50] † Kayentasuchus walkeri
    Last Modified in 12/05/13
    280106106242004
    [51] † Orthosuchus stormbergi
    Last Modified in 12/05/13
    72320320614004
    [52] Alligator mississippiensis
    Last Modified in 12/05/13
    4369366041004
    [53] † Protosuchus haughtoni
    Last Modified in 12/05/13
    81581582415004
    [54] † Protosuchus richardsoni
    Last Modified in 12/05/13
    32359359912004
    [55] † Eudimorphodon ranzii
    Last Modified in 12/05/13
    177191191935004
    [56] † Dimorphodon macronyx
    Last Modified in 12/05/13
    1592002001835004
    [57] † Lagerpeton chanarensis
    Last Modified in 12/05/13
    713313325220004
    [58] † Dromomeron gregorii
    Last Modified in 12/05/13
    7942422901004
    [59] † Dromomeron romeri
    Last Modified in 12/05/13
    31361611820004
    [60] † Marasuchus lilloensis
    Last Modified in 12/05/13
    2820320316516004
    [61] † Asilisaurus kongwe
    Last Modified in 12/05/13
    1117417421116004
    [62] † Eucoelophysis baldwini
    Last Modified in 12/05/13
    11726262690004
    [63] † Sacisaurus agudoensis
    Last Modified in 12/05/13
    2090902984004
    [64] † Lewisuchus admixtus
    Last Modified in 12/05/13
    1612912925710004
    [65] † Pseudolagosuchus majori
    Last Modified in 12/05/13
    39959526117004
    [66] † Lewisuchus/Pseudolagosuchus
    Last Modified in 12/05/13
    18122322362004
    [67] † Eocursor parvus
    Last Modified in 12/05/13
    1414014024513004
    [68] † Silesaurus opolensis
    Last Modified in 12/05/13
    193333313724004
    [69] † Pisanosaurus mertii
    Last Modified in 12/05/13
    15888829217004
    [70] † Heterodontosaurus tucki
    Last Modified in 12/05/13
    44342340028004
    [71] † Lesothosaurus diagnosticus
    Last Modified in 12/05/13
    58328327126004
    [72] † Scutellosaurus lawleri
    Last Modified in 12/05/13
    2151681651416004
    [73] † Herrerasaurus ischigualastensis
    Last Modified in 12/05/13
    45343340123004
    [74] † Staurikosaurus pricei
    Last Modified in 12/05/13
    1211511527213004
    [75] † Eoraptor lunensis
    Last Modified in 12/05/13
    100282275823004
    [76] † Saturnalia tupiniquim
    Last Modified in 12/05/13
    190192192921004
    [77] † Plateosaurus engelhardti
    Last Modified in 12/05/13
    6382380024004
    [78] † Efraasia minor
    Last Modified in 12/05/13
    66318318226004
    [79] † Tawa hallae
    Last Modified in 12/05/13
    44343343124004
    [80] † Coelophysis bauri
    Last Modified in 12/05/13
    31360360021004
    [81] † Dilophosaurus wetherelli
    Last Modified in 12/05/13
    52336334123004
    [82] † Allosaurus fragilis
    Last Modified in 12/05/13
    11371371030004
    [83] † Velociraptor mongoliensis
    Last Modified in 12/05/13
    43335334134004


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