The osteology and relationships of Vancleavea campi (Reptilia: Archosauriformes)



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    1. Lamont–Doherty Earth Observatory, Columbia University 61 Rt. 9W, Palisades, NY 10964, USA
    2. American Museum of Natural History, Division of Paleontology, Central Park West at 79th St. New York, NY 10024, USA
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    1. Department of Geoscience, 121 Trowbridge Hall, University of Iowa, Iowa City, IA 52242, USA
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    • Current address: Jackson School of Geosciences, University of Texas at Austin, 1 University Station, C1100 Austin, TX 78712-0254, USA


    1. Department of Earth Sciences, Denver Museum of Nature & Science, 2001 Colorado Blvd, Denver, CO 80205, USA
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    1. Ruth Hall Museum of Paleontology, Ghost Ranch Conference Center, Abiquiu, NM 87510-9601, USA
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Vancleavea campi Long & Murry, 1995, from the Late Triassic of western North America, represents the latest surviving non-archosaurian archosauriform known to date. We present here a detailed comparative description based on a nearly complete, articulated skeleton from the Coelophysis Quarry in north-central New Mexico and other fragmentary specimens. The unique combination of morphological features of Vancleavea is unparalleled within Reptilia; it has four unique morphologies of imbricated osteoderms covering the entire body, a short, highly ossified skull, relatively small limbs and morphological features consistent with a semi-aquatic lifestyle. Vancleavea is placed in a rigorous phylogenetic analysis examining the relationships of non-archosaurian archosauriforms, and is found to be more closely related to Archosauria than both Erythrosuchus and Proterosuchus, but outside of the crown group. The analysis confirms previously hypothesized relationships, which found Euparkeria to be the closest sister taxon of Archosauria. It is not clear whether specimens referred to Vancleavea campi represent a single species-level taxon or a clade of closely related taxa that lived through much of the Late Triassic of North America, given the poor fossil record of the taxon.