the Bayan Shireh Formation was considered to be Cenomanian to Santonian in age. The lower beds dating to 98 million and 90 million years ago (early Cenomanian to late Turonian), and the upper beds dating to 90 million and 83 million years ago (late Turonian to late Santonian). Calcite U–Pb measurements performed by Kurumada and colleagues in 2020 have estimated the exact age of the Bayan Shireh Formation from 102–86 Ma, based on dates obtained of 95.9 ± 6.0 Ma and 89.6 ± 4.0 Ma. Correlations A potential correlation between the Iren Dabasu Formation has been long suggested by most authors, mainly based on the highly similar vertebrate assemblages. However, Van Itterbeeck et al. 2005 argued against this correlation concluding that instead, the Iren Dabasu Formation was coeval with the younger Nemegt Formation based on the charophyte and ostracode assemblages; therefore, these formations were dated to the Late Campanian-Early Maastrichtian. Averianov and Sues instead proposed a correlation between the Bayan Shireh, Iren Dabasu and Bissekty formations. In 2015, Tsuihiji and team found the Iren Dabasu-Nemegt correlation to be inconsistent since the microfossil assemblages used by Van Itterbeeck and colleagues were not restricted to the Maastrichtian period and the similarities between these assemblages were most probably due to a similar deposition and climate settings. Paleobiota of the Bayan Shireh Formation In terms of biodiversity, therizinosaurs and turtles were the most abundant vertebrates across the formation, as evidenced on numerous remains. Nevertheless, hadrosauroids were fairly abundant too, particularly at the Baynshire locality with numerous remains unearthed from this area and a new unnamed hadrosauroid. In addition, most specimens of Gobihadros come from this locality. Also, niche partitioning has been reported within the therizinosaurids Erlikosaurus and Segnosaurus, and the ankylosaurs Talarurus and Tsagantegia. Mammals however, are extremely uncommon; Tsagandelta is the only mammal described so far. Besides vertebrate fossils, abundant fossil fruits have been collected from the Bor Guvé and Khara Khutul localities and they are especially abundant at Bor Guvé. Although they resemble Abelmoschus esculentus their taxonomic position remains unclear and further examination is required. Crocodylomorphs Fish Flora Mammals Pterosaurs Turtles Dinosaurs Ankylosaurids Carcharodontosaurs Ceratopsians Dromaeosaurids Hadrosaurs Ornithomimosaurs Oviraptorosaurs Pachycephalosaurs Sauropods Therizinosaurs Troodontids Tyrannosaurs See also List of dinosaur-bearing rock formations List of Asian dinosaurs Laurasia Geology of Mongolia Cretaceous Mongolia References Geologic formations of Mongolia Upper Cretaceous Series of Asia Cenomanian Stage Turonian Stage Coniacian Stage Santonian Stage Sandstone formations Shale