Fukuivenator

Fukuivenator; Temporal range: Early Cretaceous, 125–115 Ma PreꞒ Ꞓ O S D C P T J K Pg N
	Reconstructed skeleton
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Dinosauria
Clade:	Saurischia
Clade:	Theropoda
Clade:	Maniraptoriformes
Clade:	Maniraptora
Genus:	†Fukuivenator; Azuma et al., 2016
Species:	†F. paradoxus
Binomial name
	†Fukuivenator paradoxus; Azuma et al., 2016

Fukuivenator ("hunter of Fukui Prefecture") is an extinct genus of maniraptoran theropod dinosaur from the Early Cretaceous of Japan.

Discovery and naming

Skeletal reconstruction and stratigraphic map

The type species Fukuivenator paradoxus was named and described in 2016 by Yoichi Azuma, Xu Xing, Masateru Shibata, Soichiro Kawabe, Kazunori Miyata and Takuya Imai. The generic name combines a reference to the Fukui prefecture with Latin venator, "hunter". The specific name refers to the paradoxical combination of traits shown by the species.

The rocks in which the skeleton of Fukuivenator, holotype FPDM-V8461, was found in August 2007 belong to the Kitadani Formation, which is probably of Barremian or Aptian age. Radiometric dating of nearby rock units has given this formation an estimated age of somewhere between 127 and 115 million years old. The holotype consists of a partial skeleton with skull. The skeleton of F. paradoxus is currently the most complete non-avian dinosaur fossil found in Japan. The remains, including about 160 bones and bone fragments, were not found in articulation and recovered from an area of 50 by 50 centimetres (20 in × 20 in).^[1]

Description

Skull elements

Fukuivenator had an estimated length of 2.45 metres (8.0 ft) and an estimated weight of 25 kilograms (55 lb). Distinctive traits include spatulate teeth in the front praemaxillae, pointed, recurved and unserrated teeth in the maxillae and a long neck with elongated neck vertebrae.^[1]

Classification

Fukuivenator restored as a basal therizinosaur

The anatomy of Fukuivenator shows a unique combination of primitive and advanced coelurosaurian features. A phylogenetic analysis performed by the research team that described Fukuivenator found it to be a primitive member of the group Maniraptoriformes, in an unresolved position equally closely related to ornithomimosaurs, maniraptorans, and Ornitholestes. Several similarities with the Dromaeosauridae were explained as a case of convergent evolution.^[1] A 2021 study determined it a basal member of the therizinosaurs, as shown below:^[2]

Zuolong

Fukuivenator

	Erliansaurus

	Therizinosauridae

Pennaraptora

Oviraptorosauria

Paraves

	Deinonychosauria

	Avialae

Another enigmatic maniraptoran, Migmanychion, is supported as the closest taxon to Fukuivenator based on phylogenetic analyses:^[3]

Coelurosauria

Tyrannosauroidea

Guanlong

	Tanycolagreus

	Coelurus

Ornitholestes

Therizinosauroidea

	Migmanychion

	Fukuivenator

	Ornithomimosauria

	Alvarezsauroidea

	Troodontidae

	Avialae

Paleobiology

Older dromaeosaur-like skeleton reconstruction

Diet

Because of the long neck and the heterodont unserrated teeth, the probably foremost of which had flattened outer ends, the describing authors suggested that Fukuivenator was no longer a pure carnivore but had adapted itself to a herbivorous or at least omnivorous diet.^[1]

References

^ ^a ^b ^c ^d Azuma, Y., Xu X., Shibata, M., Kawabe, S., Miyata, K., and Imai, T. 2016. "A bizarre theropod from the Early Cretaceous of Japan highlighting mosaic evolution among coelurosaurians". Scientific Reports, 6(20478). doi:10.1038/srep20478
^ Hattori, S.; Kawabe, S.; Imai, T.; Shibata, M.; Miyata, K.; Xu, X.; Azuma, Y. (2021). "Osteology of Fukuiraptor paradoxus: A bizarre maniraptoran theropod from the Early Cretaceous of Fukui, Japan" (PDF). Memoir of the Fukui Prefectural Dinosaur Museum. 20: 1–82.
^ Wang, Xuri; Cau, Andrea; Wang, Zhengdong; Yu, Kaifeng; Wu, Wenhao; Wang, Yang; Liu, Yichuan (5 June 2023). "A new theropod dinosaur from the Lower Cretaceous Longjiang Formation of Inner Mongolia (China)". Cretaceous Research. 151: 105605. doi:10.1016/j.cretres.2023.105605. ISSN 0195-6671.

[Fukuivenator-1] Azuma, Y., Xu X., Shibata, M., Kawabe, S., Miyata, K., and Imai, T. 2016. "A bizarre theropod from the Early Cretaceous of Japan highlighting mosaic evolution among coelurosaurians". Scientific Reports, 6(20478). doi:10.1038/srep20478

[FukuivenatorMonograph2022-2] Hattori, S.; Kawabe, S.; Imai, T.; Shibata, M.; Miyata, K.; Xu, X.; Azuma, Y. (2021). "Osteology of Fukuiraptor paradoxus: A bizarre maniraptoran theropod from the Early Cretaceous of Fukui, Japan" (PDF). Memoir of the Fukui Prefectural Dinosaur Museum. 20: 1–82.

[3] Wang, Xuri; Cau, Andrea; Wang, Zhengdong; Yu, Kaifeng; Wu, Wenhao; Wang, Yang; Liu, Yichuan (5 June 2023). "A new theropod dinosaur from the Lower Cretaceous Longjiang Formation of Inner Mongolia (China)". Cretaceous Research. 151: 105605. doi:10.1016/j.cretres.2023.105605. ISSN 0195-6671.

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