Fig. 12From: Is the relative thickness of ammonoid septa influenced by ocean acidification, phylogenetic relationships and palaeogeographic position?Septal thickness septal slope factor data: Mann–Kendall test, septal slope factor as a function of time. The lowest point is Arietites sp. The graph shows a downward trend from the Triassic to the Jurassic with the highest peak in the Late Triassic and an increase in the CretaceousBack to article page