This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: A tiny fossil discovered exactly a century ago has caused an enormous change in our understanding of when flying insects first appeared on Earth. Rhyniognatha hirsti was discovered in 1926 in the Rhynie Chert, a renowned fossil site in northern Scotland that preserves the remnants of a 408-million-year-old wetland in extraordinary detail.
The fossil, which preserves only part of the head of an ancient arthropod and measures less than a millimeter (0.04 inches) long, was overlooked for decades as other Rhynie Chert fossils were studied instead. In 2004, however, this all changed. Studies of Rhyniognatha's jaws showed that they were very similar to those found in flying insects, leading to its identification as the world's oldest winged insect.
It became an important landmark in the timeline of insect evolution, pushing back the evolution of flying insects to at least 410 million years ago. However, doubts started to be raised about Rhyniognatha's identity. Some research suggested that it was more likely to come from an ancient centipede than an insect, making the findings of evolutionary studies based on the fossil uncertain.
To resolve this debate, a team led by Natural History Museum scientists investigated Rhyniognatha using the latest advances in microscopy. They used a confocal microscope, which uses concentrated lasers to digitally dissect a specimen, to examine the fossil in more detail than ever before. They found that the joints in Rhyniognatha's jaw aren't the same as those in modern centipedes or flying insects.
With not enough evidence left to link the fossil with certainty to either group, the team recommends that it shouldn't be used to date evolutionary trees until its identity can be confirmed. The study is published in the journal Scientific Reports. Emma Long, the study's lead author, who carried out this research while at the Natural History Museum, London, says, "For the past 22 years, Rhyniognatha has been used to estimate when flying insects, and insects more generally, evolved.
Our reexamination of the fossil now shows that it's probably not an insect at all—meaning flying insects evolved as much as 80 million years later than thought." "This really changes our understanding of how and when one of Earth's most staggeringly diverse and ecologically important groups evolved, and rewrites our understanding of the ecosystems of the past." Dr. Greg Edgecombe, co-author and merit researcher at the Natural History Museum, London, adds, "Revisiting old fossils with new technology allows us to see them in a new light, and Rhyniognatha is no exception. By using advanced microscopy techniques, we were able to digitally separate the fossil to see its key features in greater detail than ever before." "This shows the importance of museum collections for understanding our world, as we're able to apply the latest analytical advances to specimens time after time even if they were collected long ago.
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