It is known from a small holotype skeleton from the Late Triassic Tecovas Formation of Texas.

It was placed in its own genus in 2008 after having been in the collections of the University of Michigan Museum of Paleontology, with the type species being S.

[2] Based on the histology of the scutes of the holotype, the individual was a subadult that was not fully grown.

Unlike other aetosaurs, Sierritasuchus has recurved spines along its side that are serrated on the front edges.

Dorsal eminences are small projections on the surfaces of paramedian scutes that line the back of the animal on either side of the vertebral column.