Researchers working with Jurassic fossils from China have discovered insects with remarkably butterfly-like features, even though the species vanished some 40 to 50 million years before the appearance of the earliest “true” butterflies. Called kalligrammatid lacewings, these butterfly look-alikes are only distantly related to today’s fluttery monarchs and viceroys – making lacewings and butterflies a striking example of convergent evolution, according to findings published in Proceedings of the Royal Society B last week.
Kalligrammatid lacewings appeared in the Eurasian fossil record 165 million years ago, and they disappeared 45 million years later. The origins of butterflies, like the ones we have today, date back to 70 or 80 million years ago – long after kalligrammatids became extinct. However, poorly preserved kalligrammatid fossils meant that we didn’t know exactly how they looked or what they ate.
In the last decade or so, well-preserved kalligrammatid fossils were discovered in the Middle Jurassic and Early Cretaceous lake deposits of northeastern China. And now, Smithsonian Institution’s Conrad Labandeira and colleagues were able to examine specimens from 17 kalligrammatid genera using various techniques such as scanning electron microscopy and electron dispersion spectroscopy.
The body form, anatomical structure, and ecological roles of Cenozoic butterflies were already present in the mid-Mesozoic fossil record. Extinct lacewings had independently evolved wing scales, eyespots on wings that likely contained melanin, and the familiar long, tubular mouthpart called the proboscis. This suggests the two distantly-related lineages had converged on a similar mode of feeding and similar associations with seed-producing plants.
Kalligrammatid lacewings are some of the planet’s first known pollinators, and they were accessing ancient cycads and conifers long before butterflies were doing the same with flowering plants. Both kalligrammatids and many of the non-flowering plants they fed on went extinct right around the time flowering plants began to dominate some 100 million years ago. Butterflies showed up to fill those ancient roles some 50 million years later.
On the left, a modern owl butterfly (Caligo memnon), and on the right, a fossilized kalligrammatid lacewing (Oregramma illecebrosa). Some of the convergent features they independently evolved include wing eyespots and wing scales. Butterfly photo by James Di Loreto and fossil photo by Conrad Labandeira and Jorge Santiago-Blay