Dwarfed and/or small cephalopods have been recorded from many parts of the geologic column. Data assembled from preliminary studies of the Cretaceous pyritic micromorph faunas of Texas and from an Upper Triassic (Norian) fauna from the Cordillera Central of northern Peru will be given. Both of these faunas contain an abundant cephalopod assemblage, mostly small in size, which are associated with other dwarfed and non-dwarfed invertebrates. Students of cephalopods are handicapped by the relative small amount of environmental data known on recent Nautilus. Some qualitative data on the environmental relationships of fossil cephalopods is known but practically no quantitative data is available. It is suggested that evolution has probably been an important factor in causing the development of some groups of small cephalopods.

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