[2] This proposal faced support [19] and criticism [18] [20] [25] and was dropped in 2010 when new fossils of specimens from both sides of the interior seaway showed that the differences between the two morphs were not just size related, teeth from large eastern specimens retained the common characteristics of other specimens of the region and osteoderms from small specimens of the western morph were no different from those of large ones, supporting the specific separation of the two morphs, now formalized as D. rugosus and D. riograndensis.