Abstract
Author SummaryBiological structural colors are generated when light is scattered by nanostructures in tissues. Such colors have diverse functions for communication both among and between species. Structural colors are most complex in extant butterflies and moths (lepidopterans), but the evolution of such colors and their functions in this group of organisms is poorly understood. Fossils can provide insights into the evolution of biological structures, but evidence of structurally colored tissues was hitherto unknown in fossil lepidopterans. Here, we report the preservation of structurally colored scales in fossil moths with striking metallic hues from the ∼47-million-year-old (Eocene) GrubeMessel oil shales (Germany). We identify the color-producing nanostructure in the scales and show that the original colors were altered during fossilization. Preserved details in the scales allow us to reconstruct the original colors and show that the dorsal surface of the forewings was yellow-green. The optical properties of the scales strongly indicate that the color functioned as a warning signal during feeding but was cryptic when the moths were at rest. Our results confirm that structural colors can be reconstructed even in non-metallic lepidopteran fossils and show that defensive structural coloration had evolved in insects by the mid-Eocene.
Highlights
Structural color has long been of interest to biologists
Structural colors in extant lepidopterans are generated by modification of one or more components of the basic scale architecture into a biophotonic nanostructure of chitin and air [9]
Such color-generating multilayer structures can arise via specialization of the ridges and their ridgelamellae, crossribs, or the scale lumen; the lumen can exhibit various other modifications, including complex three-dimensional photonic crystals
Summary
Structural color has long been of interest to biologists. It is phenotypically significant in many organisms [1], forms the basis of diverse inter- and intra-specific communication strategies [2], and is implicated in pivotal evolutionary transitions [3]. Evidence of structural color has been reported from some fossil biotas [3,4,5,6], but has received little attention This limits our ability to reconstruct the origins of activity patterns, habitat preferences, and social and sexual signaling mechanisms [7]. Structural colors in extant lepidopterans are generated by modification of one or more components of the basic scale architecture (longitudinal ridges and transverse crossribs upon a basal lamella that is supported by columnar trabeculae in the scale lumen) into a biophotonic nanostructure of chitin and air [9].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
