Open Paleo

Fukuisaurus

Kobayashi & Azuma, 2003 foo-koo-I-sore-us

From Fukui (the prefecture in Japan where it was discovered) + Greek sauros, 'lizard'; means 'Fukui lizard'. The article notes that Fukui itself means 'Fortunate Well' in Japanese

121.4–113.2 million years ago Aptian, Early Cretaceous
Early Cretaceous stages

Fukuisaurus is a genus of herbivorous ornithopod dinosaur that lived during the Early Cretaceous in what is now Japan. The type species is Fukuisaurus tetoriensis, which was named and described in 2003.

Under dispute

Fukuisaurus tetoriensis was described as more derived than Iguanodon (Kobayashi and Azuma, 2003), and several analyses place it within Hadrosauriformes, often as the sister of Proa (Shibata and Azuma, 2015; Párraga and Prieto-Márquez, 2019; Poole, 2022). Analyses on the McDonald and Verdú matrices instead leave it in a polytomy with Hadrosauriformes at the base of Styracosterna (McDonald and colleagues, 2012; Verdú and colleagues, 2017; Santos-Cubedo and colleagues, 2021).

Diagnosis

  1. Robust, interdigitated maxilla-vomer articular surface with horizontally running ridges and grooves, indicating uniquely derived absence of pleurokinesis
  2. Large oval-shaped foramen on ventral surface of premaxilla midway between anterior tip and primary palate, connected to anterodorsal and anterior-edge foramina
  3. Lacrimal process of maxilla elevated with antorbital fenestra displaced medially to posterodorsal surface, lacking laterally exposed antorbital fenestra margin or fossa
  4. Jugal process of maxilla lacking long posterolateral projection; jugal process short and without posterolateral extension
  5. Notch on jugal wing of quadrate circular in outline, with smooth surface indicating a paraquadratic foramen

Species

Fukuisaurus tetoriensis Kobayashi & Azuma, 2003

Type species

Named for the Tetori Group, the geological formation in which the fossils were found.

Holotype
FPDM-V-40-1, FPDM-V-40-2 , Fukui Prefectural Dinosaur Museum
Material
Partial skull.
Horizon
Bonebed I Bed, Kitadani Formation, Aptian, Early Cretaceous , 121.4–113.2 million years ago
Locality
Kitadani Dinosaur Quarry, Fukui, Japan The holotype came from Bonebed I, lowest of the four informally numbered levels Shibata and Azuma (2015) recognize at the quarry. The coordinate is the quarry's, given to the second by Azuma and colleagues (2016); earlier papers state it only to the minute.

References

  1. Kobayashi, Y.; Azuma, Y. (2003). A new iguanodontian (Dinosauria: Ornithopoda) from the Lower Cretaceous Kitadani Formation of Fukui Prefecture, Japan. Journal of Vertebrate Paleontology 23(1): 166-175. Informa UK Limited. doi:10.1671/0272-4634(2003)23[166:anidof]2.0.co;2

    Named Fukuisaurus and recovered it as more derived than Iguanodon and Ouranosaurus.

    kobayashi2003a
  2. Paul, G. S. (2024). The Princeton Field Guide to Dinosaurs (3rd ed.). Princeton University Press.

    Source of the appearance features.

    paul2024a
  3. Madzia, D.; Arbour, V. M.; Boyd, C. A.; Farke, A. A.; Cruzado-Caballero, P.; Evans, D. C. (2021). The phylogenetic nomenclature of ornithischian dinosaurs. PeerJ 9: e12362. doi:10.7717/peerj.12362

    Lists Fukuisaurus in Styracosterna, outside Hadrosauriformes, on a reference phylogeny; runs no analysis of its own.

    madzia2021a
  4. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Ornithischians. Princeton University Press.

    Reports the placement among the basalmost hadrosauriforms.

    jones2026a
  5. Azuma, Y.; Xu, X.; Shibata, M.; Kawabe, S.; Miyata, K.; Imai, T. (2016). A bizarre theropod from the Early Cretaceous of Japan highlighting mosaic evolution among coelurosaurians. Scientific Reports 6(1). Springer Science and Business Media LLC. doi:10.1038/srep20478

    Prints the Kitadani Dinosaur Quarry coordinate to the second.

    azuma2016a
  6. Shibata, M.; Azuma, Y. (2015). New basal hadrosauroid (Dinosauria: Ornithopoda) from the Lower Cretaceous Kitadani Formation, Fukui, central Japan. Zootaxa 3914(4). Magnolia Press. doi:10.11646/zootaxa.3914.4.3

    Recovered Fukuisaurus as a non-hadrosauroid hadrosauriform, the sister of Proa.

    shibata2015b
  7. Párraga, J.; Prieto-Márquez, A. (2019). Pareisactus evrostos, a new basal iguanodontian (Dinosauria: Ornithopoda) from the Upper Cretaceous of southwestern Europe. Zootaxa 4555(2). Magnolia Press. doi:10.11646/zootaxa.4555.2.5

    Recovered Fukuisaurus as the sister of Proa within Hadrosauriformes.

    párraga2019a
  8. Poole, K. E. (2022). Phylogeny of iguanodontian dinosaurs and the evolution of quadrupedality. Palaeontologia Electronica 25(3): a30. doi:10.26879/702

    Recovered Fukuisaurus with Proa in an Iguanodontidae that includes Iguanodon.

    poole2022a
  9. McDonald, A. T.; Espílez, E.; Mampel, L.; Kirkland, J. I.; Alcalá, L. (2012). An unusual new basal iguanodont (Dinosauria: Ornithopoda) from the Lower Cretaceous of Teruel, Spain. Zootaxa 3595(1). Magnolia Press. doi:10.11646/zootaxa.3595.1.3

    Recovered Fukuisaurus in a polytomy with Barilium and Hadrosauriformes.

    mcdonald2012a
  10. Verdú, F. J.; Royo-Torres, R.; Cobos, A.; Alcalá, L. (2017). New systematic and phylogenetic data about the early Barremian Iguanodon galvensis (Ornithopoda: Iguanodontoidea) from Spain. Historical Biology 30(4): 437-474. doi:10.1080/08912963.2017.1287179

    Recovered Fukuisaurus in the basal polytomy of Styracosterna, outside Hadrosauriformes.

    verdú2017a
  11. Santos-Cubedo, A.; de Santisteban, C.; Poza, B.; Meseguer, S. (2021). A new styracosternan hadrosauroid (Dinosauria: Ornithischia) from the Early Cretaceous of Portell, Spain. PLoS ONE 16(7): e0253599:1-30. doi:10.1371/journal.pone.0253599

    Recovered Fukuisaurus in a polytomy with Barilium and the clade of Iguanodontidae and Hadrosauroidea.

    santos-cubedo2021a