INVESTIGADORES
EZCURRA Martin Daniel
artículos
Título:
A new basal archosauriform diapsid from the Lower Triassic of Argentina
Autor/es:
EZCURRA, M.D.; LECUONA, A.; MARTINELLI, A.
Revista:
JOURNAL OF VERTEBRATE PALEONTOLOGY
Editorial:
SOC VERTEBRATE PALEONTOLOGY
Referencias:
Lugar: Lawrence; Año: 2010 vol. 30
ISSN:
0272-4634
Resumen:
The best-known South American Early Triassic archosauriform belongs to a putative proterosuchid briefly
reported by Jos´e Bonaparte in 1981, collected from the Quebrada de los F´ osiles 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.