Fig. 5

a–b Eutomoceras aff. laubei Meek, 1877; PRC-SHM-KO-322, Chaiburi Formation, Triassic, 7º37′N, 100º5′E, a lateral view, b cross section; c, d Eutomoceras dunni Smith, 1904; PRC-SHM-KO-147, Chaiburi Formation, Triassic, 7º37′N, 100º5′E, c lateral view, d cross section; e, f Eutomoceras sp. A; PRC-134, Chaiburi Formation, Triassic, 7º37′N, 100º5′E, e lateral view, f cross section, sulcus on keel basement; g, h Eutomoceras sp. B; PRC-SHM-KO-053, Chaiburi Formation, Triassic, 7º37′N, 100º5′E, g lateral view, h cross section; i, j Eutomoceras sp. C; PRC-SHM-KO-108, Chaiburi Formation, Triassic, 7º37′N, 100º5′E, i lateral view, j cross section; k–m Eutomoceras sp. D; PRC-SHM-KO-486, Chaiburi Formation, Triassic, 7º37′N, 100º5′E, k lateral view, l cross section, m ceratitic suture