Fukuisaurus tetoriensis

Named after the Japanese Prefecture of Fukui in which it was discovered, Fukuisaurus is an ornithopod from the Early Cretaceous period. It resembles its more famous cousin Iguanodon, but has been estimated to measure less than half the length of the giant herbivore, at only 4.5 metres.

Evolutionarily speaking, Fukuisaurus was actually on a separate ‘branch’ to Iguanodon, being a basal member of the hadrosauroid clade. At first it was only known from limited skull remains, found in the Kitadani formation in 1989, which made studying the creature somewhat tricky.

However, today much of the skeleton is now known, revealing this dinosaur’s big claim to fame. Unlike other ornithopods, Fukuisaurus had a non-pleurokinetic jaw — a tricky way of saying that its bone structure indicates that it didn’t chew the tough plant matter that presumably formed much of its diet with a side-to-side motion.

Most ornithopods chomped with a side-to-side motion that used their wedge shaped teeth a bit like a guillotine to slice up their leaves. Fukuisaurus clearly had no time for that kind of thing.

OBSCURE FACT: The Kitadani Formation has yielded several unique fossils, proving to be one of Japan’s richest fossil sites. Several other species named after Fukui have also been discovered there.

FURTHER READING: If you enjoy reading about ornithopod chewing mechanics, then you cannot miss this research paper from 2009, in which the authors describe analysing microscopic scratches on fossil teeth in order to work out exactly how they moved.