Fukuiraptor

It Wasn’t a Hind Leg! The Claw Mystery of “Kitadani-ryu”

The discovery of Fukuiraptor dates back to excavation surveys that began in 1989 in Katsuyama City, Fukui Prefecture (Kitadani Formation, Tetori Group).
Initially, this dinosaur was nicknamed “Kitadani-ryu” (Kitadani Dragon) after the location name.

The Dromaeosaur Misunderstanding

In 1992, a large “claw” measuring about 10 cm was discovered.
At first, this claw was thought to be a “hind toe claw (sickle claw)” of a raptor (dromaeosaur), similar to those featured in the movie Jurassic Park.
Consequently, Kitadani-ryu attracted attention as “Japan’s dromaeosaur.”

The True Identity Was a “Hand”

However, subsequent detailed research revealed a surprising fact.
That huge claw was not from a hind leg, but actually from a “forelimb (hand).”
This disproved the dromaeosaur theory, and in 2000, it was formally described as Japan’s first carnivorous dinosaur, “Fukuiraptor.”

From Allosaurus to “Megaraptor”: Shifting Classification

Fukuiraptor is also known as a dinosaur whose taxonomic position has changed significantly.

Former Reconstruction (Allosaurus Type)

When first described, it was classified as a “Carnosaur (Allosauroidea)” and was thought to be closely related to China’s Sinraptor.
Therefore, early restoration drawings and skeletal models were created with a robust, Allosaurus-leaning style for the head.

Latest Reconstruction (Megaraptor Type)

Recent research has revealed that they are a primitive group of “Megaraptorans,” which thrived in South America and Australia.
Megaraptorans are characterized by long, slender snouts.
As a result, recent reconstructions of Fukuiraptor are increasingly depicted with sleeker facial features.
However, since a complete skull has not yet been found, its “true face” remains shrouded in mystery.

A 6-Meter Apex Predator: Thin and Giant “Hand Claws”

Fukuiraptor was the first carnivorous dinosaur in Japan to have its full skeleton reconstructed, and it is now one of the symbols of the Fukui Prefectural Dinosaur Museum.

4.2 Meters Even as a Young Individual

The total length of the discovered individual is about 4.2 meters, but bone fusion indicates that it is still a “young individual in the midst of growth.”
It is estimated that adults reached a total length of 5–6 meters and weighed about 175 kg, making it one of the largest carnivorous dinosaurs found in Japan.

Greatest Weapon

Their greatest characteristic is the forelimb, which was the deciding factor in their classification.
Developed larger than that of Allosaurus, the claws were shaped to be “large yet very thin.”
It is believed that they used these sharp hand claws as weapons to prey on contemporaries like Fukuisaurus (Iguanodontia).