Camouflage patterns in Nautilus, and their implications for cephalopod paleobiology

Cowen, R., Gertman, R. & Wiggett, Gail: Camouflage patterns in Nautilus , and their implications for cephalopod paleobiology.
Formal analysis of the pigment patterns of adult Nautilus shows that they are perfectly camouflaged for life in open water. But because of their accretionary growth pattern, juveniles are not fully camouflaged for open water: this supports previous suggestions that young Nautilus are benthonic. The principles of camouflage are used to re-assess some facets of cephalopod paleobiology. The life orientation of some early cyrtocones is re-interpreted. 'Ornament' on ammonoids is seen as camouflage structure, and we infer photic-nektonic, photic-benthonic, and aphotic habitats for three major morphological groups of ammonites. Sexual dimorphism in ammonites was probably accompanied by sexual separation in habitat, except for a short (annual) mating season. This is not inconsistent with modern cephalopod biology.