INVESTIGADORES
LECUONA Agustina
congresos y reuniones científicas
Título:
GRACILISUCHUS STIPANICICORUM ROMER: ANATOMIC, SYSTEMATIC AND PHYLOGENETIC UPDATE
Autor/es:
LECUONA, A.
Lugar:
Diamante
Reunión:
Jornada; XXIX Jornadas Argentinas de Paleontología de Vertebrados; 2015
Institución organizadora:
CICYTTP
Resumen:
Gracilisuchus stipanicicorum is a pseudosuchian archosaur coming from the outcrops of the Ladinian Chañares Formation of La Rioja, Argentina. It is represented by six incomplete specimens deposited in national and USA collections by decades overlooked. A detailed revisionof this species was performed in order to clarify its skeletal representation, revise its diagnosis and description, as well as resolve its phylogenetic relationships under the light of the actual knowledge of Archosauriformes. The present study was focused on the cranial, axial, anteriorlimb, and osteoderms elements of Gracilisuchus. It was possible to emend its diagnosis on the basis of the identification of new characters(e.g., sclerotic ossicles in lateral contact not overlapped) and autapomorphies (e.g., supratemporal fenestra wider than long; axial neural spinetall and vertical), as well as some overlooked characters and anatomical regions (e.g., staggered paramedian osteoderms; gastralia present).The phylogenetic relationships of Gracilisuchus were tested through the addition of characters and taxa to a previous analysis, resulting in adata matrix with 483 characters (15 new) and 82 species (seven new). The analysis allowed to confirm the taxonomic identity of all six Gracilisuchus specimens and to resolve its position consistently with previous studies, although presenting better support values and solving previous polytomies. Gracilisuchus is nested within Gracilisuchidae, one node distance from the Suchia node, as the sister taxon to Yonghesuchussupported by four synapomorphies (e.g., infratemporal fenestra with no participation of postorbital).