In addition, they proposed that the skulls represented the most derived phytosaur species in North America, due to their supratemporal fenestrae being hidden in dorsal view.

[1][2] The authors had previously mentioned the unnamed phytosaur species in a 1992 paper on "Triassic Stratigraphy and Paleontology" in New Mexico.

[4] The first report from outside New Mexico, a skull impression (MNA V3498) from the Wingate Sandstone of Utah, was initially described by Morales & Ash (1993).

The oldest Redondasaurus specimen is an incomplete skull (UCMP V78034/119436) from the Petrified Forest Member (Chinle Formation) of Rio Arriba County, New Mexico.

The large sample of approximately 13 Redondasaurus gregorii skulls have helped to reconstruct growth series and sexual dimorphism trends in the species.

Complete skulls of this species are uncommon, but some fragmentary narrow-snouted phytosaur specimens from the Redonda Formation may be part of the taxon.

The diagnostic criteria given in 1993 for the new genus was as follows:"Phytosaurid that differs from other genera in possessing supratemporal fenestrae that are essentially concealed in dorsal view and whose anterior margin only slightly emarginates the skull roof and has wide squamosal-postorbital bars.

These new specimens encompass a range of sizes from hatchlings to adults and possibly include the first evidence of sexual dimorphism in the taxon.

[4] Disagreement on the validity of Redondasaurus emerged 1995, when Long and Murry did not accept it and referred to the specimen as Pseudopalatus pristinus instead.

The reason for this may have been that the type specimen of Redondasaurus is missing the entire narial area, left side of its snout, the anterior two thirds of the right premaxilla, and most of its palate.

[9] In addition to this, the term used by Savage to describe the first specimen found in 1939,[1] Machaeroprosopus, continues to be used by some scholars in place of Redondasaurus as the genus name.

Additional paleontological and sedimentary evidence support the hypothesis that the climate of the Chinle was strongly influenced by high levels of precipitation.

[3][6] The Chinle Group is particularly important to paleontologists interested in aetosaurs, as it has been critical in establishing their biochronology in the Late Triassic.

[4] Given the recent acquisition of additional diagnostic characteristics, and the increase in number of Redondasaurus skulls recognized in literature, it is likely that the use of the genus as an index fossil will expand to other deposits and even globally.