Extended Data Fig. 7: Ammonoid morphological occupation across three intervals based on multiple species and specimens.

a, Multiple species from one genus and multiple specimens for the same species. b, The result of interspecific variations of some representatives. Plots based on the raw data, including 191 species and 219 specimens. Notably, genera dating from the Changhsingian and characterized by stronger shell ornamentations exhibited higher levels of interspecific variation, as exemplified by Paratirolites and Alibashites. Conversely, genera from the Induan fauna displayed fewer variations, as observed in Ambites and Mullericeras.