Fukuiraptor (Greek for "theif of Fukui") (foo-KWEE-rap-tor) was a genus of megaraptoran theropod dinosaur of the Early Cretaceous epoch (either Barremian or Aptian) that lived in what is now Japan. It was discovered in the Kitadani quarry near Katsuyama in the Fukui prefecture. A large claw was discovered that was first thought to be the sickle-claw belonging to a large, unknown member of the dromaeosaurid (or raptor) family of dinosaurs, so it was named Fukuiraptor, or "Fukui thief".
However, closer examination a few years ago and more bones discovered of this elusive predator proved that this was, in fact, a type of theropod that was closely related to the more well-known Megaraptor. This is very similar to what happened with Fukuiraptor's close relatives Megaraptor and Aoniraptor The paleontologists believed that the huge claws of this narrow predator was a toe-claw iconic to the raptor family. However, based on the small size of this megaraptoran it's been debated whether or not it was a juvenile, but a few years later several more specimens were found that were even smaller than the first specimen, so it's beginning to look like they didn't get very big. This is a very significant find in paleontology history because until then, we did not know that large carnivores were capable of living on the small island of Japan.
Description and history[]
Reconstructed skeleton and holotype fossils on the lower right
The type specimen is a partial skeleton (designated FPDM-V97122) discovered in the Kitadani quarry near Katsuyama in the Fukui prefecture. It is thought that this specimen, which would have measured about 4.2 metres long in life and weighed 175 kg, was not mature and an adult may have been larger. The remains of many other individuals have been found in the quarry, with numerous humeri, femurs, and teeth being assigned to this species. However, the other individuals recovered from the same locality are mostly juveniles that were smaller than the holotype (Currie & Azuma, 2006), in the smallest case less than a quarter of the holotype's size. A tooth (NDC-P0001) discovered in a block of conglomerate from the Sebayashi Formation has been referred to Fukuiraptor as well.
Description[]
Size comparison
As indicated by its slender phalanges, Fukuiraptor was a relatively lightly built animal, regardless of its maturity. In 2010 Gregory Paul gave a length of 5 meters (16 ft) and a weight of 300 kg (660 lbs). Molina-Pérez and Larramendi estimated a length of 4.3 meters (14.1 ft) and a weight of 590 kg (1,300 lbs) in 2016.
However, it was likely the biggest predator in its environment and was quite capable of eating about anything it could catch. Probably the most likely reason for its smallness is because of island-dwarfism, which is caused when an animal is trapped on a small island and throughout time it gets smaller and smaller to be able to survive by not having to eat or drink as much as it would being much larger. This is especially likely since Japan is such a small island and, because the sea-levels were much higher back then, would've minimized its size even more. It's not quite known what Fukuiraptor's main prey item would've been, but considering how short food supply was on the island it likely mostly survived on lizards, passing-by pterosaurs, or possibly even fish. Some people believe that the Fukuiraptor might've hunted down a possible rival, the Fukuisaurus, a Hadrosaur.
The distinctive teeth of Fukuiraptor show similarities with both carcharodontosaurids (being very compressed and blade-like, as well as having wrinkled enamel) and tyrannosaurids (having oblique blood grooves near the serrations). The holotype also had very large and flat manual unguals (hand claws), which played a role in its initial classification as a dromaeosaurid (as the hand claws were mistaken for foot claws) as well as its current classification as a megaraptoran.
What's unusual about this relatively unknown megaraptoran is that it had relatively long arms with such large claws in relative to its body size, this could indicate that it was a skillful fisher and that may have been its main food source. Like other carnosaurs, Fukuiraptor was bipedal, and walked on two back legs with three toes with sharp talons on the ends. It had a long tail that was designed to help it walk more balanced and it had sharp, blade-like teeth that were designed to tear through the flesh of its unlucky victims.
Classification[]
Initially considered a member of the Dromaeosauridae when first discovered, its initial describers considered it a carnosaur, related to Allosaurus. More recent studies consider it a megaraptoran, an enigmatic group which may have been part of the family Neovenatoridae. However, more recently, another analysis has proposed that all megaraptorans are actually tyrannosauroids, which would reclassify Fukuiraptor as a tyrannosauroid coelurosaur. Recent cladistic analysis of the theropod Gualicho has suggested that Fukuiraptor and other megaraptorans are either allosauroids, or non-tyrannosauroid basal coelurosaurs.
Below is a cladogram reconstructing the position of Fukuiraptor in the Megaraptora as per Delcourt and Grillo, 2018.
| Megaraptora |
| |||||||||||||||||||||||||||
Paleoecology[]
Stratigraphic positions of the non-avialan dinosaurs of the Kitadani Formation, Japan.
In the Kitadani Formation, where fossils of Fukuiraptor have been recovered, fossils of other vertebrates have been preserved. Among the species that have been properly described and named are Fukuisaurus tetoriensis, a styracostern ornithischian, Fukuititan nipponensis, a titanosauriform sauropod, Koshisaurus katsuyama, a hadrosauroid ornithischian, Fukuivenator paradoxus, a mairaptoriform theropod, and Fukuipteryx prima, an avialan as defined by the authors.
JPInstitute.com Description[]
Fukuiraptor was a medium-sized meat-eater that lived in what is now Japan. Scientists first thought it was a member of the raptor family, but after studying the fossils they now believe it was related to Allosaurus. It is thought that this specimen was not mature and that an adult would be considerably larger.
This specimen caused some confusion upon its initial discovery because its hand claw was mistaken for the killer claw on the foot of a dromaeosaur. It is now considered to be a basal member of the allosaur family and possibly a species of Allosaurus similar or identical to the Australian species.
Appearance in other media[]
Jurassic Park[]
- Fukuiraptor appears in Jurassic World: Alive as a Omega.
 |
Read more Fukuiraptor on Jurassic Park Wiki |