Insect fossil from Devonian may shed light on birth of insect flight

LAWRENCE — As scientists have toiled to chronicle of the evolution of insects, a frustrating blank spot in the fossil record has masked one of the most critical points in insects' development — the Devonian, or roughly 365 million years ago.

The biodiversity of insects, the greatest radiation of all life today, during the Devonian is captivating to researchers because it was around this period when insects first diversified. They developed novel feeding strategies and first evolved wings, becoming the original organisms on Earth to evolve powered flight.

"Insects do have a good fossil record, but unfortunately not from this critical time period," said Michael Engel, professor of ecology and evolutionary biology at the University of Kansas. "Prior to this, only two definitive insects have been recorded from the Devonian, and both are exceptionally fragmentary."

Now, Engel and colleagues have described the first complete insect fossil from the Devonian. The specimen illuminates the timing of changes to insect biology that resulted in flight. Their findings appear in the Aug. 2 issue of Nature.

"The current fossil is much more complete than any other record from the Devonian and comes from the Late Devonian — somewhat younger than the other two Devonian fossils, but far more complete," said Engel, who also serves as senior curator at KU's Natural History Museum. "The features of this fossil indicate that it, like a fossil I described in 2004, was not of the most primitive lineages of insects, which are largely wingless. This indicates that significant diversification had already taken place and that winged insects were present at the time, supporting the notion that wings evolved much earlier than was believed."

"It helps close a giant gap in the fossil record — namely the lack of fossil material from the early Devonian fossils through to the much better deposits of the mid-Carboniferous," said Engel. "It helps to narrow this gap in the fossil record of the most diverse lineage of life on this planet."