A 324-million-year-old fossil, long misidentified as a crustacean, has been reclassified as one of the earliest known insects, potentially rewriting the evolutionary history of life on Earth.
The specimen, cataloged as No. 28852, spent four decades in a drawer at the San Diego Natural History Museum, where it was labeled as Tesnusocaris goldichi, an ancient shrimp-like creature.
Cambridge University PhD student Erik Tihelka, upon seeing images of the fossil in a textbook, traveled to San Diego to examine the specimen. Tihelka's detailed analysis led to its reclassification as Chosha praecursor, an insect. This reclassification places it among the earliest undisputed insects discovered.
The discovery is significant because it helps to fill a gap in the fossil record, known as the "hexapod gap," a period of approximately 60 million years where early insects seem to have vanished from Earth.
Tihelka identified classic insect features in the fossil, including six legs attached to the thorax, an egg-laying organ, and a tail-like filament. However, the fossil also possessed additional pairs of paddle-like legs on its abdomen, a characteristic typically found in crustaceans.
Scientists speculate that these paddle-like legs may have aided the creature in gliding through water, providing a rare glimpse into the evolution of ancient aquatic ancestors into the insects that inhabit the planet today. The fossil was originally collected in Brewster County, Texas, and arrived at the San Diego museum in 1985, receiving its crustacean classification in 1991.
The San Diego Natural History Museum has since moved the fossil from storage to a glass display case on its lower level, allowing visitors to view the specimen that bridges the evolutionary gap between aquatic and terrestrial life.
"There is nothing that makes a curator happier than having a researcher use the collection," Tom Deméré, the museum's director of paleontology, told the San Diego Union Tribune. "To have a specimen that has been in the collection for 40 years have a new life in the scientific literature, and hopefully in the general public’s mind, shows that new discoveries can be made."