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| Nipponopelta yezoensis Oyabu, Kobayashi, Zelenitsky, Fiorillo & Kano, 2026 |
Highlights
• Nipponopelta yezoensis is the first ankylosaur formally named from Japan.
• The taxon is more closely related to North American nodosaurids than Asian taxa.
• Coastal environments may have played a role in interregional nodosaurid radiations.
Abstract
Nodosaurid dinosaurs are mainly known from North America and Europe, with rare occurrences in South America and Asia. A partial skull, discovered in a concretion from the upper part of the marine Hikagenosawa Formation (upper Cenomanian) in Yubari City, Hokkaido, Japan, was initially described in 2005 and identified as a nodosaurid based on its dentition and occipital bone morphology. However, its taxonomic status remained unresolved. In this study, three-dimensional CT reconstructions reveal detailed morphological features justifying the naming of a new taxon, Nipponopelta yezoensis gen. et sp. nov., the first named Japanese ankylosaur based on unique characters in the occipital region. Phylogenetic analyses indicate that Nipponopelta yezoeisis is deeply nested within derived North American and European nodosaurids and distantly related to other Asian nodosaurids. Ancestral geographic analysis suggests that Nipponopelta yezoensis and its close relatives originated in Laramidia, Appalachia, and Asia, indicating a wide ancestral area. Habitat reconstruction reveals that Nipponopelta yezoensis preferred marine-influenced environments, likely inhabiting coastal or estuarine areas. This preference for coastal environments played a significant role in its dispersal patterns across different regions.
Keywords: Ankylosauria; Nodosauridae; Cretaceous; Palaeobiogeography; Asia
Nipponopelta yezoensis gen. et sp. nov.
Shumpei Oyabu, Yoshitsugu Kobayashi, Darla K. Zelenitsky, Anthony R. Fiorillo and Manabu Kano. 2026. A new nodosaurid ankylosaur (Dinosauria: Ornithischia) from the Upper Cretaceous Hikagenosawa Formation in Japan reveals dispersal pattern of Asian nodosaurid ankylosaurs. Cretaceous Research. DOI: doi.org/10.1016/j.cretres.2026.106477 [21 August 2026]
https://tiisys.com/blog/2026/09/02/post-202824/
北海道産恐竜化石を「ニッポノペルタ・エゾエンシス」と命名～約1億年前の"海辺の恐竜"が明かす、白亜紀の大陸間移動～（総合博物館 教授 小林快次）
