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Posts Tagged ‘coevolution’

Triassic Butterfly Park: Oldest Fossil Unhinges Flower-Pollinator Timeline

Posted by Richard Conniff on January 10, 2018

Modern Glossata

By Richard Conniff/Scientific American

For years, researchers studying core samples drilled from deep in the Earth have noticed odd flecks of material, possibly from insects—and generally treated them as a distraction from the real work: They focused instead on pollen and spores as a continuous record for understanding past ecosystems. But a surprising abundance of those flecks in a recent sample from northern Germany has now led a team of researchers to pay closer attention.

Writing in the journal Science Advances, Timo van Eldijk and his co-authors describe their find as the earliest fossil record of Lepidoptera, from about 201 million years ago, at the boundary between the Triassic and Jurassic periods. The new find fits the timeline for evolution of the Lepidoptera suggested by molecular evidence and helps correct a puzzling gap in the fossil record.

Triassic Wing Scale

The study looks at 70 specimens, found in a drill core from more than 300 meters below the surface, and identifies them as the wing scales that give butterflies and moths their spectacularly varied colors and patterns.  A light microscope, and later a scanning electron microscope, revealed the scales to be petal-like structures.  Some of them are beautifully preserved, with neatly ridged surfaces, herringbone webbing between the ridges, “micro-ribs,” and in some cases, perforations in the surface.

The perforations turned out to be a critical detail. They indicate, according to the co-authors, that a moth of that period had the hollow wing scales characteristic of Glossata, the taxonomic group that includes all modern moths and butterflies equipped with a sucking proboscis. The oldest previously known such fossil was from 129 million years ago–just as the flowering plants were making their spectacular emergence across the planet.  And the accepted theory was that the sucking proboscis only emerged at that point as a product of co-evolution between flowers and the insects that pollinate them.

That co-evolution, and the often exquisitely precise matchup between flower and pollinator, have been a subject of perennial fascination for naturalists.  In one of the most celebrated stories in all of botany, for instance, Read the rest of this entry »

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