Vision of Trilobites and Polarized Light

This chapter introduces to trilobites, extinct arthropods of the Palaeozoic and their diversity of morphological characteristics, lifestyles and visual systems. We explore the perspective to reveal something about the capability of perception and the relevance of linearly polarized light for these animals which became extinct about a quarter of a billion years ago. The Appendix of this chapter provides a theoretical polarization-optical analysis of the miraculous trilobite calcite lenses with their birefringent (double-refracting) properties. We show that the intensity pattern of light below a double-refracting typical trilobite calcite lens is polarization dependent, and thus, the polarization state of incident light can in principle be inferred from such an intensity distribution.