Insects are everywhere—in the air, on the ground, in the ground, and sometimes in your house and food. Yet there are none whatsoever in the known fossil record between 385 million and 325 million years ago. The earliest known insect fossil is a 385-million-year-old wingless creature that looks like a silverfish. But for the next 60 million years there is not so much as a single dragonfly, grasshopper or roach.
One hypothesis suggests that chokingly low oxygen levels kept insect diversity from soaring during the gap and that these creatures proliferated only once the life-giving gas increased.
But advances in the understanding of atmospheric oxygen levels are challenging that idea, explains Sandra Schachat, a paleoentomologist at Stanford University, who led a recent study that modeled the gas's availability during the hexapod gap. Atmospheric oxygen at the time was much higher than once believed, according to the research, which was published in January in the Proceedings of the Royal Society B.
Schachat and her team combed through fossil information from a public paleontology database and realized there was something special about many of the insect fossils that came after the gap: they had wings.
The origins of wings, then, must lie within the gap itself. Lurking somewhere in it, there may be undiscovered fossils that could reveal how insects became the first animals to take to the skies.
Editor's note: Read the full study (behind paywall)
Read full, original post: Mysterious Insect Fossil Gap Explained