ANCIENT butterflies exquisitely preserved in amber hint that the winged insects evolved far earlier than previously thought. They may even have fluttered around the heads of dinosaurs, more than 65 million years ago.
The oldest butterfly fossils found in rocks suggest they evolved about 40 or 50 million years ago. But the amber specimens, although just 15 to 25 million years old, have changed that view by shedding light on the earlier evolution of their ancestors. The amber pieces come from the Dominican Republic and each contains a metalmark butterfly, Voltinia dramba, which is now extinct. 鈥淚t was just incredible,鈥� says Robert Robbins of the Smithsonian Institution in Washington DC. 鈥淚t鈥檚 no different than if you took a modern-day butterfly and put it under a light microscope.鈥�
Robbins and his colleagues showed that the amber-entombed insects had already diverged from their closest known relative, Voltinia danforthi. Fossils of V. danforthi are found in Mexico.
Advertisement
Because the butterflies can鈥檛 easily disperse across anything other than rainforest, Robbins thinks V. dramba must have ridden from central America to the Caribbean on islands shifted by plate tectonics. In that case, the two species must have diverged before the islands began to move 40 to 50 million years ago (Proceedings of the Royal Society B, DOI: 10.1098/rspb.2004.2691). That suggests more primitive butterflies were around long before that, perhaps 65 million years ago or earlier.