3-metre dinosaur bone identified 25 years after Fukushima find

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Scientists have identified a dinosaur bone discovered in 1999 in Fukushima, Japan, as the sternal plate of a 3-metre-long iguanodontian. The fossil, found on the grounds of the Iwaki City Ammonite Center, sat unstudied for over 20 years before researchers from the center and other institutions examined its shape and features. Their analysis, published in Paleontological Research, showed it belongs to a styracosternan, a group of herbivorous dinosaurs that lived during the Late Cretaceous period, around 90 to 88 million years ago.

The find is significant because most iguanodontian remains in Japan are fragmentary, making it hard to estimate species diversity and body size. A nearly complete skeleton from Japan was previously attributed to an 8-metre-long iguanodontian. The 3-metre specimen suggests these dinosaurs occupied a broader size range in coastal ecosystems. The study notes that the rocks where the fossil was found formed in a shallow marine environment, indicating the carcass may have been washed into the sea from nearby river plains and wetlands.