Dinosaur bone found in 1999 finally identified as 3-metre species after 27 years

Photo credit: Jstage.jst.go.jp A small dinosaur bone discovered in Fukushima, Japan, more than two decades ago has given scientists a new glimpse into the diversity of ancient life along East Asia’s coast.The fossil, found in 1999 and left largely unexamined for years, has now been identified as part of the breastbone of a plant-eating dinosaur known as an iguanodontian. Based on comparisons with related animals, researchers estimate that the dinosaur was approximately 3 metres long; much smaller than other iguanodontian fossils previously found in the same geological formation.The finding suggests that dinosaurs of different sizes lived in the coastal environments of what is now Fukushima during the Late Cretaceous, around 90 to 88 million years ago. The study titled 'An iguanodontian sternal plate from the Upper Cretaceous Ashizawa Formation (Futaba Group) of Fukushima Prefecture, Japan' was published in Paleontological Research in 2026.A fossil hiding in plain sightThe story began when an isolated bone was discovered on the grounds of the Iwaki City Ammonite Center in Fukushima Prefecture. The centre is located within the Ashizawa Formation, a group of rocks formed in a shallow ...