A morphological re-study of three spinicaudatan species from the Middle–Upper Jurassic of Gansu Province, northwestern China

Abstract

By using scanning electron microscopy, the type materials of Euestheria shandanensis Chen in Zhang et al., 1976, Euestheria jingyuanensis Chen in Zhang et al., 1976 and Sinokontikia lianmuqinensis Wang, 1985 from the Middle–Upper Jurassic of Gansu Province were re-examined. As a result, some critical characters of taxonomic value were revealed: 1) Euestheria shandanensis has typical Triglypta ornamentation on its carapace, and should be assigned to the genus Triglypta Wang, 1984; 2) Euestheria jingyuanensis closely resembles Sinokontikia (Novojilov, 1958) in ornamentation, which is characterized by the very fine reticulation on the dorsal part of the carapace, and tubercles ornamented on growth bands in the ventral part of the carapace. The tubercles are gradually changed from the thick, bulge mesh wall. It probably implies that Euestheria jingyuanensis and Sinokontikia share the same ancestor.