Amber-encased fossil shines light on evolution of bioluminescent insects

Artistic reconstruction of Cretophengodes azari male and female in the undergrowth of a Cretaceous rainforest Dinghua Yang - Trapped in amber for 100 million years, an exceptionally well-preserved, light-producing beetle sheds light on the diversification of bioluminescent beetles in the Cretaceous period and provides the missing fossil link between fireflies' living relatives. With over 3,500 described species, light-producing beetles are the most diverse bioluminescent terrestrial animals. Fireflies, fire beetles, glow-worm beetles and their kin use light to ward off predators, attract mates, and some females even use it to attract unsuspecting males to eat. Historically, despite their diversity, the evolution of bioluminescence in beetles has been poorly understood. "Most light-producing beetles are soft-bodied and quite small, and so have a scant fossil record. However, this new fossil, found in amber from northern Myanmar, is exceptionally well-preserved, even the light organ on its abdomen is intact,' said Dr. Chenyang Cai , research fellow at the University of Bristol and associate professor at NIGPAS. The presence of a light organ on the abdomen of the male provides direct evidence that that adults of Cretophengodes were capable of producing light, some 100 million years ago.