Project 437: M. D. Ezcurra, A. Lecuona, A. Martinelli. 2010. A New Basal Archosauriform Diapsid from the Lower Triassic of Argentina. Journal of Vertebrate Paleontology. 30 (5):1433-1450.
Specimen: † Koilamasuchus gonzalezdiazi (MACN/PV:18119)
View: Natural external molds


The best-known South American Early Triassic archosauriform belongs to a putative proterosuchid briefly reported by José Bonaparte in 1981, collected from the Quebrada de los Fósiles Formation (Puesto Viejo Group, Argentina). This specimen consists of well-preserved natural external molds of a partial postcranium that preserve dorsal vertebrae, osteoderms, a dorsal rib, a possible gastralium, a chevron, a humerus, an ilium, two metapodials, and an ungual. We re-describe this specimen and identify autapomorphies that allow us to recognize Koilamasuchus gonzalezdiazi, gen. et sp. nov. The presence of an iliac blade with a slightly convex dorsal margin and with a maximum length more than 3 times its maximum height places Koilamasuchus within Archosauriformes. A cladistic analysis of basal Archosauriformes positions Koilamasuchus more crownwards than Proterosuchus, Sarmatosuchus, Fugusuchus, and Osmolskina, as the sister taxon of the clade that includes Erythrosuchidae and Archosauria. Proterosuchidae is found to be paraphyletic. The presence of an iliac preacetabular process, a pubic peduncle that forms an angle lower than 45° to the longitudinal axis of the ilium, and dorsal body osteoderms positions Koilamasuchus in Archosauriformes more crownwards than proterosuchids. Koilamasuchus is more basal than erythrosuchids within Archosauriformes because of the presence of dorsal ribs with a poorly developed proximal end. Koilamasuchus importantly increases the diversity of Archosauriformes during the biotic recovery following the Permo-Triassic mass extinction.

Read the article »

Project DOI: 10.7934/P437,
This project contains
  • 1 Media
  • 3 Documents
  • 1 Taxon
  • 1 Specimen
Total size of project's media files: 4 MB

Download Project SDD File
Currently Viewing:
MorphoBank Project 437
  • Creation Date:
    15 November 2010
  • Publication Date:
    06 February 2013
  • Project views: 14926


    member name taxa specimens media
    MorphoBank Curator
    Project Administrator
    Last logged in 02/06/13
    Maureen Admin
    Full membership
    Last logged in 02/06/13
    Martin Ezcurra
    Full membership
    Last logged in 01/24/11
    Seth Kaufman
    Full membership
    Last logged in Never

    Project has no matrices defined.

    Project views

    type number of views Individual items viewed (where applicable)
    Total project views14926
    Project overview2755
    Media views4302Media search (3769 views); M55529 (533 views);
    Taxon list1641
    Specimen list1992
    Documents list1573
    Views for media list1918

    Project downloads

    type number of downloads Individual items downloaded (where applicable)
    Total downloads from project210
    Document downloads13Matrix (5 downloads); Character List A (5 downloads); Character List B (3 downloads);
    Project downloads197