LAUSR

ABSTRACT Many extant invertebrate and vertebrate taxa possess osteological, keratinous, or chitinous structures that are photoluminescent: that is, variably coloured and patterned when observed under ultraviolet light. These features are frequently associated with inter- and/or intraspecific display. Among terrestrial vertebrates, keratinous photoluminescent capabilities are especially well documented in birds. Inspired by recent discoveries, we consider whether non-bird dinosaurs, the evolutionary precursors to birds, might also have possessed photoluminescent display structures. Dinosaurs and other bird-line archosaurs (collectively ornithodirans) often possess extravagant structures that likely functioned in visual display. From a phylogenetic bracketing perspective, UV-sensitive visual capabilities in extant reptiles – including Aves – support the likelihood of tetrachromatic vision in extinct ornithodirans. The ability to perceive the ultraviolet, or near-ultraviolet, range of the visible light spectrum, combined with the presence of extravagant, keratinous-covered display structures, supports proposals that these features may have played an important role in inter- and intraspecific visual displays and communication in extinct Mesozoic bird-line archosaurs.