PVL 4597 a specimen attributed to Gracilisuchus by Lecuona and Desojo 2011. It is indeed a Ladinian (Late Miiddle Triassic) sister, but nests closer to the base of the Dinosauria, along with Lewisuchus at present. I'm eager to see the rest of this specimen. It is plesiomorphic in many regards to all higher dinosaurs.
Lecuona and Desojo reported: PVL 4597 (the ‘Tucuman specimen’ of Romer 1972, Bonaparte 1975a), nearly complete skull and
mandible in articulation, an almost complete presacral vertebral
series with articulated paramedian dorsal osteoderms, two
sacral vertebrae, an incomplete caudal vertebral series, both
ilia, left pubis, both ischia, an almost complete left hind limb,
fragmentary right hind limb, and several undetermined fragments of bone.