“Iguanodontia is a significant group of little – to large-bodied ornithopod dinosaurs– roughly 2 m (6.6 feet) to higher than 10 m(33 feet)in length– that existed from the Late Jurassic through the current Cretaceous,” stated University of Tsukuba paleontologist Masami Kondo and associates from Japan and Canada.

“Iguanodontians achieved an around the world circulation throughout this time, and their fossils are understood from every continent.”

“Asia was an essential area for their diversity throughout Laurasia, as dispersals took place both in between Asia and North America and in between Asia and Europe.”

“A high variety of iguanodontian types has actually been recuperated from the Cretaceous of eastern and main Asia.”

“The increased variety of reports of iguanodontian fossils from Japan over the previous 20 years is considerable, as this area represents an easternmost margin of Cretaceous Laurasia.”

In the research study, Dr. Kondo and co-authors re-examined a separated right sternal plate excavated in 1999 near Iwaki in Japan’s Fukushima prefecture.

The fossil originates from the Ashizawa Formation, part of the Futaba Group, an approximately 90-million-year-old layer of sandstone and mudstone transferred on an ancient seabed.

The specimen had actually sat unstudied for over 20 years after being tentatively identified a hadrosauroid (duck-billed) dinosaur bone.

The paleontologists identified the hatchet-shaped bone comes from an indeterminate styracosternan, a broad group within Iguanodontia that consists of hadrosauroids and their close family members.

Its functions carefully look like those seen in more obtained iguanodontian types instead of in primitive ones.

Based upon contrasts with the sternal bones of associated types, the scientists approximate this iguanodontian dinosaur determined just about 3 m (10 feet) in body length, making it little by the basic category plan for these dinosaurs.

“This is considerably smaller sized than that of other iguanodontian fossils formerly uncovered from the very same development,” they stated.

“Because bigger iguanodontians, consisting of hadrosauroids, are understood to have actually existed in Japan throughout the Late Cretaceous, the discovery recommends that iguanodontians of differing body sizes populated the seaside environments of East Asia.”

“The finding supplies brand-new insights that even more substantiate the variety of ancient seaside communities.”

The group’s outcomes were released on July 6 in the journal Paleontological Research

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Masami Kondo et al2026. An iguanodontian sternal plate from the Upper Cretaceous Ashizawa Formation (Futaba Group) of Fukushima Prefecture, Japan. Paleontological Research 30: 122-134; doi: 10.2517/ prpsj.250042