 Aetosaur material was first described by Swiss paleontologist Louis Agassiz in 1844 . He named the genus Stagonolepis from the Lossiemouth Sandstone in Elgin , Scotland , but considered it to be a Devonian fish rather than a Triassic reptile . This may be because he considered the strata to be part of the Old Red Sandstone , and thus Paleozoic in age . Agassiz mistook the osteoderms for large rhomboidal scales , which he thought were arranged in a similar pattern to those of gars . He also thought that these supposed scales were very similar to those of the lobe @-@ finned fish Megalichthys due to their large size . 
