Fig. 4
From: Patterns of the evolution of aptychi of Middle Jurassic to Early Cretaceous Boreal ammonites
Changes of shell cross-section and aptychi outline within the lineage of the Late Volgian Garniericeratinae. Biohorizons are marked by numerals (1 evolutum, 2 tenuicostatum, 3 cheremkhensis, 4 subfulgens, 5 involutum, 6 internicarinatum, 7 catenulatum). Outline of praestriaptychi is given without scale: a aptychus of Garniericeras catenulatum (Fisch.), MSU, Ivanovskoe; b aptychus of Kachpurites involutum Rogov, in litt., MSU6503, Marievka; c aptychus of Kachpurites subfulgens (Nik.), MSU 121/12, Kashpir; d, e aptychus of Kachpurites tenuicostatum Rogov, in litt., d MSU 121/42, Marievka; e MSU 116/5, Eganovo = Mironenko (2014, pl.II, Fig. 5)