Fig. 8
From: Pseudoinversion of septal sutures in Middle Jurassic–Lower Cretaceous non-heteromorph ammonites
a—Kachpurites involutus Rogov with normal sutural pseudoinversion, lateral view; Upper Volgian, Fulgens Zone, involutus horizon, Kuntsevo district, Moscow; specimen no. IGM MK 4148/2; b—Craspedites (Craspedites) planus Schulg., with transitional sutural pseudoinversion, lateral view; Upper Volgian, Okensis Zone, Kheta river, northern Siberia, specimen no CNIGR 51/9565; c, d—Craspedites (Trautscholdiceras) sp. juv. with weakly developed transitional pseudinversion, Upper Volgian, Nodiger Zone, Ogarkovo, Kostroma region, specimen no. PIN 3682/5477; e, f—Craspedites (Taimyroceras) sachsi Igoln. with normal pseudoinversion, lateral view; lower Ryazanian, Sibiricus Zone, Nordvik, northern Siberia; specimen no. TsSGM 2035/1; e—full view; b—enlarged photo of inner whorls showing early appearance of pseudoinversion