Middle Jurassic spinicaudatan Shizhuestheria from the Sichuan Basin and its ontogenetic implication

The diagnosis of the Middle Jurassic spinicaudatan genus Shizhuestheria is revised following the re-examination under a scanning electron microscope of a type specimen from Yanxi of Shizhu, and the newly collected specimens from Xintiangou of Chengjiang Town, Beibei, Chongqing. Small-sized reticulations occur not only in the middle-sized reticulations on growth bands on the dorsal side of the carapace, but also on growth bands on the ventral side of the carapace, which have been overlooked in the original description. The shift from wide dorsal growth bands to narrow ventral ones might indicate an onset of sexual maturity, and the transition in biological priorities from rapid juvenile growth to reproductive activities.