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Kalligrammatid lacewing (left) and modern owl butterfly (right). Credit: James DiLoreto, Smithsonian

Butterflies Forty Million Years Before Butterflies

There’s a group of fossils insects that look really quite a lot like butterflies. They had broad wings with scales and pigmented eyespots. Their mouthparts were long probing straws. They likely fed from plants and pollinated them in return. They’re as butterfly-esque as it’s possible to be.

Except these creatures were flying around between 40 and 85 million years before the first butterflies existed.

They were kalligrammatid lacewings, and they were doing butterflies before butterflies even were a thing. Their resemblance is a coincidence, an extraordinary example of convergent evolution, the process two groups turn up to life’s party accidentally wearing the same outfits.

The kalligrammatids appeared around 165 million years ago, during the Jurassic period, and died out 45 million years later. During their reign, they were among the largest and most conspicuous insects around. Time has since been unkind to them: many became fossilised but most have been badly preserved. Scientists have commented on their similarities to butterflies for more than a century, but no one has been able to thoroughly study their anatomy—that is, until Conrad Labandeira and Dong Ren from Capital Normal University in Beijing got their hands on some beautifully preserved specimens from northeastern China.

They found that some kalligrammatid species had eyespots on their first pair of wings, which look remarkably like those of, say, the peacock or owl butterflies. The earliest members of the group had plain, monochromatic wings, but several lineages independently evolved simple, solid spots. Three groups then elaborated these into more complex patterns—alternating concentric rings of light and dark pigments that looked increasingly eye-like.

Butterflies would go through the same transition about 110 million years later, from monochromatic moths to simple-spotted species like the tree nymph, to complex-spotted ones like the squinting brown bush. Since both butterflies and kalligrammatids developed spots on the outer edges of their wings, it’s likely that these patterns arose in both cases to deflect predator attacks.

Kalligrammatid mouthparts also went through a very butterfly-like transition. The earliest members had chewing mandibles, which then lengthened and zipped up into a single, flexible, straw-like tube. The resemblance isn’t a superficial one: both butterfly and kalligrammatid straws had analogous microscopic structures, were powered by sucking pumps in the head, and came in a similar variety of shapes and sizes. It seems that kalligrammatids also used these straws for much the same purpose as butterflies: to drink from plants. Labandeira and Ren even found one specimen with a plug of nectar-like fluid trapped in the straw.

Flowering plants, which butterflies drink from, hadn’t colonised the land during the kalligrammatid era, so these early insects probably fed from ancient plants like conifers and cycads (which are still around) and bennettitaleans (which are not). Indeed, the straws of many kalligrammatid were perfect fits for the deep fluid- and pollen-bearing parts of bennettitaleans. And some specimens were found with dustings of conifer pollen around their heads.

This ancient partnership between kalligrammatid and their plant partners ended around 120 million years ago, but it wasn’t lost entirely. Flowers started spreading over the world at roughly the same time, and about 40 million years later, they entered into the same relationship with butterflies.