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X-ray scans reveal ordinary vertebrae inside Iran's spider-tailed viper

Scientists used X-ray computed tomography to examine the tail of the spider-tailed horned viper and found its bones are typical of vipers.

The spider-tailed horned viper, native to Iran, has evolved a tail tip that looks like a spider, tricking birds into approaching for a strike. To investigate whether this unusual exterior is matched by distinctive bones, a team led by paleontologist Georgios Georgalis scanned the holotype specimen using X-ray computed tomography at the Field Museum. The three-dimensional images revealed that the tail’s vertebrae are standard for vipers, contradicting expectations of a specialized skeleton.

The study, appearing in The Anatomical Record, illustrates how soft-tissue adaptations can be invisible in fossil records. It also demonstrates how advanced imaging can extract new data from long-held museum specimens without damage, offering fresh insights into evolutionary biology.

Why it matters

The research shows that dramatic animal adaptations may leave no trace in fossils, affecting how scientists interpret extinct species.

In this story

spider-tailed horned viperPseudocerastes urarachnoidesX-ray computed tomographyvertebraemuseum collectionsevolutionary adaptationsoft-tissue mimicry
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