Science News · Wetenschap

324-Million-Year-Old Fossil Reveals Insects Once Had 24 Legs

A newly identified 324-million-year-old fossil, named Chosha praecursor, suggests that insects may have once possessed up to 24 legs, a significant departure from the six-legged anatomy characteristic of modern insects. This discovery provides crucial insights into the evolutionary transition from multi-legged aquatic ancestors to the terrestrial hexapods we know today.

The fossil, unearthed in West Texas, exhibits a body plan unlike any living insect, featuring 18 extra abdominal legs in addition to the standard three pairs of walking legs. Researchers describe it as one of the oddest and potentially most consequential insect fossils ever found, bridging a gap in the fossil record.

Initially mistaken for a crustacean and stored in a museum for decades, the specimen was re-examined by paleoentomologist Erik Tihelka. Using polarized light filters, Tihelka identified key insect features, including a three-segmented thorax, an extended abdomen, antennae, and tail structures, alongside the numerous abdominal legs which may have aided in swimming or scuttling through shallow seas.

The discovery of Chosha praecursor and similar multi-legged fossils suggests a lineage of semi-aquatic proto-insects. It is hypothesized that one of these ancestors transitioned to land, shedding surplus legs until only six remained, eventually giving rise to the vast diversity of insect species on Earth. This finding offers a significant piece of evidence for a poorly understood period of evolutionary change from aquatic to terrestrial life.

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