Project 2781: M. R. Stocker, C. A. Brochu, E. C. Kirk. 2021. A new caimanine alligatorid from the Middle Eocene of Southwest Texas and implications for spatial and temporal shifts in Paleogene crocodyliform diversity. PeerJ. 9:e10665.
Specimen: † Chinatichampsus wilsonorum (unvouchered)
View: Dorsal view

Abstract

Dramatic early Cenozoic climatic shifts resulted in faunal reorganization on a global scale. Among vertebrates, multiple groups of mammals (e.g. adapiform and omomyiform primates, mesonychids, taeniodonts, dichobunid artiodactyls) are well known from the Western Interior of North America in the warm, greenhouse conditions of the early Eocene, but a dramatic drop in the diversity of these groups, along with the introduction of more dry-tolerant taxa, occurred near the Eocene–Oligocene boundary. Crocodyliforms underwent a striking loss of diversity at this time as well. Pre-Uintan crocodyliform assemblages in the central Western Interior are characterized by multiple taxa, whereas Chadronian assemblages are depauperate with only Alligator prenasalis previously known. Crocodyliform diversity through the intervening Uintan and Duchesnean is not well understood. The middle Eocene Devil’s Graveyard Formation (DGF) of southwest Texas provides new data from southern latitudes during that crucial period. A new specimen from the middle member of the DGF (late Uintan–Duchesnean) is the most complete cranial material of an alligatorid known from Paleogene deposits outside the Western Interior. We identify this specimen as a caimanine based on notched descending laminae of the pterygoids posterior to the choanae and long descending processes of the exoccipitals that are in contact with the basioccipital tubera. Unlike Eocaiman cavernensis, the anterior palatine process is rounded rather than quadrangular. The relationships and age of this new taxon support the hypothesis that the modern distribution of caimanines represents a contraction of a more expansive early Cenozoic distribution. We hypothesize that the range of caimanines tracked shifting warm, humid climatic conditions that contracted latitudinally toward the hothouse-icehouse transition later in the Eocene.


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Article DOI: 10.7717/peerj.10665

Project DOI: 10.7934/P2781, http://dx.doi.org/10.7934/P2781
This project containsMatrices
  • 1 Media
  • 1 Matrix
  • 1 Document
  • 59 Taxa
  • 1 Specimen
  • 202 Characters
Total size of project's media files: 1.58M

Download Project SDD File
Total scored cells: 6950
Total media associated with cells: 0
Total labels associated with cell media: 0
Characters
Total characters: 202
Total characters with associated media: 0
Total characters with media with labels: 0
Total character states: 473
Total character states with associated media: 0
Total character states with media with labels:0
Total unordered/ordered characters:202/0
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MorphoBank Project 2781

    Authors' Institutions

    • University of Iowa

    • University of Texas at Austin

    • Virginia Tech (Virginia Polytechnic Institute and State University)



    Members

    member name taxa specimens media chars character
    media
    labels
    cell scorings
    (scored, NPA, "-")
    cell
    medialabels
    rules
    Michelle Stocker
    Project Administrator
    5811197000
    (0, 0, 0)
    000
    Christopher Brochu
    Full membership
    1005006950
    (6950, 0, 0)
    000
    Christopher Kirk
    Full membership
    0000000
    (0, 0, 0)
    000


    Taxonomic Overview for Matrix 'M26813' (58 Taxa)

    taxon unscored
    cells
    scored
    cells
    no cell
    support
    NPA
    cells
    "-" cellscell images labels on
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    [1] † Borealosuchus sternbergii
    Last Modified in 01/06/21
    2018218200003
    [2] † Boverisuchus vorax
    Last Modified in 01/06/21
    5314914900003
    [3] † Leidyosuchus canadensis
    Last Modified in 01/06/21
    3816416400003
    [4] † Diplocynodon ratelii
    Last Modified in 01/06/21
    4116116100003
    [5] † Diplocynodon hantoniensis
    Last Modified in 01/06/21
    3916316300003
    [6] † Diplocynodon darwini
    Last Modified in 01/06/21
    4016216200003
    [7] † Diplocynodon deponiae
    Last Modified in 01/06/21
    105979700003
    [8] † Diplocynodon remensis
    Last Modified in 01/06/21
    5315014900003
    [9] † Stangerochampsa mccabei
    Last Modified in 01/06/21
    4016216200003
    [10] † Albertochampsa langstoni
    Last Modified in 01/06/21
    130727200003
    [11] † Brachychampsa montana
    Last Modified in 01/06/21
    2617617600003
    [12] † Brachychampsa sealeyi
    Last Modified in 01/06/21
    139636300003
    [13] Alligator sinensis
    Last Modified in 07/03/20
    519719700003
    [14] Alligator mississippiensis
    Last Modified in 07/03/20
    120120100003
    [15] † Alligator mefferdi
    Last Modified in 01/06/21
    5914314300003
    [16] † Alligator thompsoni
    Last Modified in 01/06/21
    8212012000003
    [17] † Alligator olseni
    Last Modified in 01/06/21
    5814414400003
    [18] † Alligator mcgrewi
    Last Modified in 01/06/21
    2817417400003
    [19] † Alligator prenasalis
    Last Modified in 01/06/21
    3017217200003
    [20] † Ceratosuchus burdoshi
    Last Modified in 01/06/21
    121818100003
    [21] † Allognathosuchus polyodon
    Last Modified in 01/06/21
    125777700003
    [22] † Allognathosuchus wartheni
    Last Modified in 01/06/21
    6413813800003
    [23] † Navajosuchus mooki
    Last Modified in 01/06/21
    7312912900003
    [24] † Wannaganosuchus brachymanus
    Last Modified in 01/06/21
    7912312300003
    [25] † Procaimanoidea kayi
    Last Modified in 01/06/21
    7113113100003
    [26] † Procaimanoidea utahensis
    Last Modified in 01/06/21
    8311911900003
    [27] † Arambourgia gaudryi
    Last Modified in 01/06/21
    9810410400003
    [28] † Necrosuchus ionensis
    Last Modified in 01/06/21
    167353500003
    [29] † Tsoabichi greenriverensis
    Last Modified in 01/06/21
    141616100003
    [30] † Purussaurus mirandai
    Last Modified in 01/06/21
    8212012000003
    [31] † Purussaurus brasiliensis
    Last Modified in 01/06/21
    107959500003
    [32] † Purussaurus neivensis
    Last Modified in 01/06/21
    4515715700003
    [33] † Mourasuchus atopus
    Last Modified in 01/06/21
    5814414400003
    [34] † Mourasuchus amazonensis
    Last Modified in 01/06/21
    160424200003
    [35] † Mourasuchus arendsi
    Last Modified in 01/06/21
    144585800003
    [36] † Mourasuchus nativus
    Last Modified in 01/06/21
    120828200003
    [37] † Eocaiman cavernensis
    Last Modified in 01/06/21
    161414100003
    [38] Caiman yacare
    Last Modified in 07/03/20
    120120100003
    [39] Caiman crocodilus
    Last Modified in 07/03/20
    120120100003
    [40] Caiman latirostris
    Last Modified in 07/03/20
    619619600003
    [41] † La venta caiman
    Last Modified in 01/06/21
    143595900003
    [42] † Melanosuchus fisheri
    Last Modified in 01/06/21
    127757500003
    [43] Melanosuchus niger
    Last Modified in 07/03/20
    419819800003
    [44] Paleosuchus trigonatus
    Last Modified in 07/03/20
    319919900003
    [45] Paleosuchus palpebrosus
    Last Modified in 01/06/21
    619619600003
    [46] † Caiman brevirostris
    Last Modified in 01/06/21
    136666600003
    [47] † Centenariosuchus gilmorei
    Last Modified in 01/06/21
    173292900003
    [48] † Globidentosuchus brachyrostris
    Last Modified in 01/06/21
    126767600003
    [49] Crocodylus affinis
    Last Modified in 07/03/20
    2917317300003
    [50] † Asiatosuchus germanicus
    Last Modified in 01/06/21
    6114114100003
    [51] † Gnatusuchus pebasensis
    Last Modified in 01/06/21
    8611611600003
    [52] † Kuttanacaiman iquitosensis
    Last Modified in 01/06/21
    7612612600003
    [53] † Caiman wannlangstoni
    Last Modified in 01/06/21
    10010210200003
    [54] † Protocaiman peligrensis
    Last Modified in 01/06/21
    170323200003
    [55] † Eocaiman palaeocenicus
    Last Modified in 01/06/21
    189131300003
    [56] † Eocaiman itaboraiensis
    Last Modified in 01/06/21
    1984400003
    [57] † TxVP 45911-1
    Last Modified in 01/06/21
    124787800003
    [58] † Bottosaurus harlani
    Last Modified in 01/06/21
    122808000003


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    Project overview182
    Matrix views112Matrix used in analysis (37 views); Matrix landing page (75 views);
    Documents list59
    Media views191Media search (165 views); M692323 (26 views);
    Views for media list60
    Specimen list111
    Taxon list399
    Bibliography39




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    type number of downloads Individual items downloaded (where applicable)
    Total downloads from project34
    Project downloads25
    Matrix downloads9Matrix used in analysis (9 downloads);