Judging from the absolute dates this guy is not a dinosaur but one of the late Permian mammal-like reptires. It might be a scutosarid, judging by the bony skull, but I'd need to see a primary article, and that is most likely behind a pay wall.
This beast lived right up to the catastrophy that ended most life forms that had evolved in the Paleozoic era. 252 MYA is the date of that decimation. It wasn't until about 225 MYA that the first dinosaurs appeared in the Mid-Triassic, and probably mannals as well, who lived for the next 160 MY under their feet.