title: A bizarre theropod from the Early Cretaceous of Japan highlighting mosaic evolution among coelurosaurians.
abstract: Our understanding of coelurosaurian evolution, particularly of bird origins, has been greatly improved, mainly due to numerous recently discovered fossils worldwide. Nearly all these discoveries are referable to the previously known coelurosaurian subgroups. Here, we report a new theropod, Fukuivenator paradoxus, gen. et sp. nov., based on a nearly complete specimen from the Lower Cretaceous Kitadani Formation of the Tetori Group, Fukui, Japan. While Fukuivenator possesses a large number of morphological features unknown in any other theropod, it has a combination of primitive and derived features seen in different theropod subgroups, notably dromaeosaurid dinosaurs. Computed-tomography data indicate that Fukuivenator possesses inner ears whose morphology is intermediate between those of birds and non-avian dinosaurs. Our phylogenetic analysis recovers Fukuivenator as a basally branching maniraptoran theropod, yet is unable to refer it to any known coelurosaurian subgroups. The discovery of Fukuivenator considerably increases the morphological disparity of coelurosaurian dinosaurs and highlights the high levels of homoplasy in coelurosaurian evolution.
authors.affiliation: Institute of Dinosaur Research, Fukui Prefectural University, 4-1-1 Kenjojima, Matsuoka, Eiheiji, Fukui, 910-1195 Japan.|Fukui Prefectural Dinosaur Museum, 51-11 Terao, Muroko, Katsuyama, Fukui 911-8601, Japan.
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Azuma
authors.affiliation: Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China.
authors.forename: Xing
authors.initials: X
authors.lastname: Xu
authors.affiliation: Institute of Dinosaur Research, Fukui Prefectural University, 4-1-1 Kenjojima, Matsuoka, Eiheiji, Fukui, 910-1195 Japan.|Fukui Prefectural Dinosaur Museum, 51-11 Terao, Muroko, Katsuyama, Fukui 911-8601, Japan.
authors.forename: Masateru
authors.initials: M
authors.lastname: Shibata
authors.affiliation: Gifu Prefectural Museum, 1989 Oyana, Seki, Gifu 501-3941, Japan.
authors.forename: Soichiro
authors.initials: S
authors.lastname: Kawabe
authors.affiliation: Institute of Dinosaur Research, Fukui Prefectural University, 4-1-1 Kenjojima, Matsuoka, Eiheiji, Fukui, 910-1195 Japan.|Fukui Prefectural Dinosaur Museum, 51-11 Terao, Muroko, Katsuyama, Fukui 911-8601, Japan.
authors.forename: Kazunori
authors.initials: K
authors.lastname: Miyata
authors.affiliation: Fukui Prefectural Dinosaur Museum, 51-11 Terao, Muroko, Katsuyama, Fukui 911-8601, Japan.
authors.forename: Takuya
authors.initials: T
authors.lastname: Imai
mesh_terms: D000818:Animals; D005075:Biological Evolution; D025061:Dinosaurs / Q000033:anatomy & histology*; D007758:Ear, Inner / Q000033:anatomy & histology; D005121:Extremities / Q000033:anatomy & histology; D005580:Fossils; D007564:Japan; D010802:Phylogeny; D012886:Skull / Q000033:anatomy & histology; D013131:Spine / Q000033:anatomy & histology; D014070:Tooth / Q000033:anatomy & histology