1Institute of Dinosaur Research, Fukui Prefectural University, 4-1-1 Matsuoka Kenjojima, Eiheiji, Fukui 910-1195 Japan.
2Fukui Prefectural Dinosaur Museum, 51-11 Terao, Muroko, Katsuyama, Fukui 911-8601 Japan.
Commun Biol. 2019 Nov 14;2:399. doi: 10.1038/s42003-019-0639-4. eCollection 2019.
The Early Cretaceous basal birds were known largely from just two-dimensionally preserved specimens from north-eastern China (Jehol Biota), which has hindered our understanding of the early evolution of birds. Here, we present a three-dimensionally-preserved skeleton (FPDM-V-9769) of a basal bird from the Early Cretaceous of Fukui, central Japan. Unique features in the pygostyle and humerus allow the assignment of FPDM-V-9769 to a new taxon, . FPDM-V-9769 exhibits a set of features comparable to that of other basalmost birds including . Osteohistological analyses indicate that FPDM-V-9769 is subadult. Phylogenetic analyses resolve as a non-ornithothoracine avialan basal to and outgroup of the Pygostylia. This phylogenetic result may imply a complex evolutionary history of basal birds. To our knowledge, FPDM-V-9769 represents the first record of the Early Cretaceous non-ornithothoracine avialan outside of the Jehol Biota and increases our understanding of their diversity and distribution during the time.
早期白垩纪基础鸟类主要来自于中国东北（热河生物群）的二维保存标本，这阻碍了我们对鸟类早期进化的理解。在这里，我们展示了一个来自日本福井早白垩世的三维保存的基础鸟类骨架（FPDM-V-9769）。独特的尾综骨和肱骨特征使 FPDM-V-9769 被分配到一个新的分类单元， 。FPDM-V-9769 表现出一系列与其他最基础鸟类相当的特征，包括 。骨组织学分析表明，FPDM-V-9769 是亚成体。系统发育分析将 FPDM-V-9769 解析为一个非鸟兽脚类的基础鸟类，位于 和外群的 Pygostylia 之后。这一系统发育结果可能暗示了基础鸟类的复杂进化历史。据我们所知，FPDM-V-9769 代表了热河生物群以外的早白垩世非鸟兽脚类的首次记录，增加了我们对它们在该时期多样性和分布的理解。
