The Ulansuhai Formation has traditionally been considered to date to the Aptian-Albian stages of the Late Cretaceous, due to similarities between the Ulansuhai fauna and known Aptian formations. However, radiometric dating done on underlying formations has shown this to be incorrect. Due to the age of underlying rocks, the Ulansuhai Formation cannot be older than the Turonian stage of the Late Cretaceous, about 92 Ma.
^ abcdefgWeishampel, David B; et al. (2004). "Dinosaur distribution (Early Cretaceous, Asia)." In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. Pp. 563-570. ISBN 0-520-24209-2.
^Kobayashi, Y., and Lu, J.-C. (2003). "A new ornithomimid dinosaurian with gregarious habits from the Late Cretaceous of China." Acta Palaeontol. Pol., 48: 235–259.
^Benson, R.B.J. and Xu, X. (2008). "The anatomy and systematic position of the theropod dinosaur Chilantaisaurus tashuikouensis Hu, 1964 from the Early Cretaceous of Alanshan, People’s Republic of China." Geol. Mag., 145: 778–789. doi:10.1017/S0016756808005475
^Benson, R.B.J., Carrano, M.T and Brusatte, S.L. (2010). "A new clade of archaic large-bodied predatory dinosaurs (Theropoda: Allosauroidea) that survived to the latest Mesozoic." Naturwissenschaften, 97(1):71–78. doi:10.1007/s00114-009-0614-x
^"Table 4.1," in Weishampel, et al. (2004). Page 73.
^"Table 17.1," in Weishampel, et al. (2004). Page 364.
^"Table 5.1," in Weishampel, et al. (2004). Page 138.