Decades-old Fukushima bone reveals tiny 3-metre iguanodontian from Late Cretaceous

A solitary fossil unearthed in 1999 on the premises of the Iwaki City Ammonite Center in Fukushima Prefecture remained in a collection for more than two decades before being re-examined. A 2026 study published in Paleontological Research identified the specimen as a sternal plate of an indeterminate styracosternan iguanodontian, estimating the dinosaur’s length at about 3 metres—significantly smaller than other iguanodontian fossils from the Upper Cretaceous Ashizawa Formation.

This suggests that Late Cretaceous coastal ecosystems in present-day Fukushima hosted herbivores of varied body sizes. The finding underscores how museum holdings can yield new scientific insights when revisited with modern techniques. Researchers caution the bone alone cannot determine whether it represents a distinct small species or a juvenile of a larger form, but it adds evidence of ecological diversity among East Asian dinosaurs. The work also informs broader discussions of iguanodontian dispersal across the ancient supercontinent Laurasia.