Fig. 6From: Patterns of the evolution of aptychi of Middle Jurassic to Early Cretaceous Boreal ammonitesAptychi co-occurring with Sinzovia sasonovae Wright (left photograph made in field, right the same specimen photographed in laboratory with well-visible inner organic black layer), MSU 121/45, Lower Aptian, Volgensis Zone, Shirokij Buerak, member 3Back to article page