The specimen was found southeast of Mt. Linnaeus in the Abajo Mountains of southeastern Utah, in an area called the Red Bluffs, part of the Manti-La Sal National Forest (Figure 1). The Abajo Mountains were formed when an igneous intrusive body uplifted and exposed the Mesozoic continental strata (Witkind 1964). In the immediate vicinity of where the procolophonid specimen was recovered, the exposed strata in ascending order are the Owl Rock Member of the Upper Triassic Chinle Formation, Church Rock Member of the Chinle Formation, and Upper Triassic/Lower Jurassic Wingate Sandstone (Figure 2) (Stewart et al. 1972). Although the skull was recovered in a block as float, its location and matrix make it fairly likely that it originated from the Owl Rock Member. Extensive prospecting of the area has revealed that bone is fairly common within the Owl Rock Member but is absent from the Church Rock Member and Wingate Sandstone. Most bone within the Owl Rock Member at the locality occurs within channel conglomerates that are dominated by intraformational clasts (Figure 2). However, the matrix surrounding the procolophonid indicates it is derived from a fine-grained dark red mudstone or siltstone that is one of the most common fluvial sediments within the Owl Rock Member.
The Upper Triassic Chinle Formation is exposed throughout southern Utah, southeastern Colorado, northeastern New Mexico, and northern Arizona (Stewart et al. 1972), and represents dominantly fluvial floodplain sediments. In southeastern Utah, the Shinarump Conglomerate, Monitor Butte Member, Moss Back Member, an undifferentiated Petrified Forest Member, Owl Rock Member, and Church Rock Member represent the Chinle Formation in ascending sequence. In the Abajo Mountains, Stewart et al. (1972: p. 288) interpreted the lowest exposed unit as the Moss Back Member, and did not identify the Petrified Forest Member. At the locality itself, the unit in contact with the igneous intrusion is the Owl Rock Member. In this area, the Owl Rock Member is dominated by slope to ledge-forming orange, red, and purple mudstone-siltstones. Thin layers of fine sandstones are also present. Interspersed between these layers are ledge-forming units of intraformational conglomerates and pedogenic limestone that is generally purple in color (Figure 2).
Recently, debate has centered on the interpretation of the depositional setting of the Owl Rock Member. A number of workers suggested that the unit was dominated by lacustrine and marginal lacustrine environments with the limestones representing lake deposits (e.g. Blakey and Gubitosa 1983; Dubiel 1989, 1993). This interpretation was challenged by Lucas and Anderson (1993) who interpreted all the limestones as exclusively pedogenic in nature and, thus, having no bearing upon their depositional setting. With this in mind, Tanner (2000) undertook a detailed sedimentologic study of the Owl Rock Member. He found that while the limestones did display a pedogenic component, they were not exclusively so, and probably represented small ephemeral lakes and ponds within a predominantly fluvial system. This interpretation also confirms that the Owl Rock Member conforms to the general Late Triassic-Early Jurassic trend of increasing aridity (Tanner 2000). Thus, the Owl Rock Member most likely represents a fluvial floodplain with sinuous streams and small ephemeral lakes and ponds that was drier than the underlying Petrified Forest Member.