Mantle expansion upon the conch in the Late Devonian ammonoid Erfoudites

Abstract

Specimens of the Late Devonian ammonoid species Erfoudites rugosus sp. nov. from the Rhenish Massif of Germany show an additional wrinkled structure that covers the body chamber ornament. The pattern closely resembles the dorsal wrinkle layer known from many ammonoids; the course of the wrinkles is radial, partially following the growth line course. This wrinkle structure is interpreted as resulting from a secretion of the mantle, which expanded ventrally or dorsally over the conch.