Article: The palaeobiology of the Cretaceous irregular echinoids Infulaster and Hagenowia

The taxonomy of the infaunal holasteroids Infulaster and Hagenowia is revised in the light of new material from the Senonian Chalk of southern England. Investigation of the plating structure in Hagenowia permits a more precise definition of its species, and a better understanding of the evolution of the rostrum. The majority of structural modifications in the Infulaster-Hagenowia lineage were caused directly, or indirectly, by apical elongation and size reduction. A detailed study of test and ambulacral pore morphology, tuberculation, and spines, taken in comparison with living echinoids, allows reconstruction of the life habits of Infulaster and Hagenowia. The evolutionary changes are related to the adoption of a specialized method of feeding and an attempt to avoid predation.