The sedimentological characteristics of the basal part of the Middle Dinosaur Member suggest deposition on tidal flats and in small tidal channels of a lagoonal paleoenvironment. The ostracod "Bythocypris sp." from the member indicates polyhaline to euhaline conditions. Slightly higher up, a faunal sample dominated by the bivalve "Eomiodon" and an ostracod assemblage composed of brackish to freshwater taxa is indicative of a brackish water paleoenvironment with distinct influx of freshwater as revealed by the nonmarine ostracod genus "Cypridea", charophytes, and other freshwater algae. The paleoenvironment of the ostracod assemblages of the Middle Dinosaur Member changed upsection from a marine setting in the basal parts through alternating marine-brackish conditions to freshwater conditions in the higher parts of this member. The highly sporadic occurrence, in this part of the section, of molluscs typical of marginal marine habitats indicates only a very weak marine influence, at sabkha-like coastal plains with ephemeral brackish lakes and ponds are recorded in the upper part of the Middle Dinosaur Member. This part also contains pedogenic calcretes indicating subaerial exposure and the onset of soil formation. The calcrete intraclasts within adjacent sandstone beds testify to erosive reworking of calcrete horizons. The presence of crocodyilforms indicates freshwater to littoral environments and adjacent terrestrial areas.