San Diego Museum Fossil Identified as Ancient Insect
A 324 million-year-old specimen previously labeled a crustacean is confirmed as one of the oldest insect fossils.
Updated on Oct. 28, 2026 in Geology
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Researchers have identified a 324 million-year-old fossil at the San Diego Natural History Museum as a rare, ancient insect. The specimen, named Chosha praecursor, had been misclassified as a crustacean for 40 years.
Why it matters
The discovery is significant because it helps bridge a 80 million-year gap in the fossil record, shedding light on the early evolution of hexapods. The fossil features distinct insect-like physical characteristics including slender antennas and a segmented body.
The specimen was examined using polarized light and microscopic analysis to verify its six walking legs and 18 aquatic appendages. It is part of the San Diego Natural History Museum collection, which contains 1.6 million total artifacts.
The players
Erik Tihelka
A researcher at the University of Cambridge who identified the insect fossil using specialized microscopy techniques.
San Diego Natural History Museum
A regional institution that houses 1.6 million artifacts and currently displays the Chosha praecursor in its basement exhibit.
The details
Erik Tihelka, a researcher at the University of Cambridge, identified the fossil after spotting a drawing in a second-hand paleontology textbook. The specimen, which originated in West Texas, is now on display as part of the Amazement in the Basement exhibit.
Timeline
The hexapod gap spanned 385 to 322 million years ago.
The Chosha praecursor fossil is 324 million years old.
The fossil was housed at the San Diego museum starting in 1985.
The Big Picture
This finding fundamentally shifts our understanding of insect evolution by providing a missing link within the hexapod gap. It disproves the legacy classification of the specimen as a crustacean and resets the timeline for early terrestrial insect emergence.
This discovery offers San Diego residents a new look at natural history by providing concrete evidence of early evolutionary milestones in the region's broader fossil context. The specimen is currently accessible for public viewing within the museum's basement exhibit.
The takeaway
This discovery reminds us that scientific breakthroughs often come from re-examining existing records with new tools. Amateur enthusiasts and professionals alike should look closely at legacy collections, as they may contain previously misunderstood data.
Further reading
Learn more about local findings in the Geology section.
Source note: This article includes information reported by KPBS.
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