Die Runzelschicht — ein Leichtbauelement der Ammonitenschale

Ammonoid Shell Microstructure

“…3). Bayer (1974) described the wrinkle layer of Mesozoic ammonoids as occurring only on the dorsal side. He argued that the wrinkle layer did not constitute a separate layer but was merely part of the inner prismatic layer.…”

Ammonoid Shell Structures of Primary Organic Composition

“…On account of the densely spaced growth lines and apertural shell thickening, the two specimens of Paranannites were apparently adult. These two also have remains of the black layer and wrinkle layer (‘Runzelschicht’; Walliser 1970; Bayer 1974). One of these specimens (499C) shows a darkened terminal aperture (Text‐fig.…”

Functional interpretation of inner shell layers in Triassic ceratid ammonites

“…The wrinkle layer was previously thought to occur only in the shell wall of Palaeozoic and Triassic ammonoids. However, several recent studies have shown that this layer occurs in Jurassic and Cretaceous ammonoids too (Walliser 1970;Senior 1971;Bayer 1974;Kulicki 1979;Doguzhaeva 1981;Zakharov & Grabovskaja 1984).…”