研究者業績

Tadahiro Ikeda

  (池田 忠広)

Profile Information

Affiliation
Professor, Institute of Natural and Environmental Science, University of Hyogo
Degree
Doctor of Philosophy(Mar, 2007, Kagoshima University)

J-GLOBAL ID
202001000131136010
researchmap Member ID
R000002102

Papers

 27
  • Tomonori Tanaka, Kentaro Chiba, Tadahiro Ikeda, Michael J. Ryan
    Papers in Palaeontology, 10(5), Sep 2, 2024  
    Abstract The herbivorous dinosaur clade Ceratopsia flourished in the northern hemisphere during the Late Jurassic to Late Cretaceous. Previous palaeobiogeographic studies have suggested that their initial diversification occurred in Asia, with early‐branching neoceratopsians extending their geographical range to North America sometime during the Barremian to Albian. However, the specific timing and mode of their dispersal from Asia to North America remains unknown. Here we describe a new, early‐branching neoceratopsian, Sasayamagnomus saegusai gen. et sp. nov., from the Albian Ohyamashimo Formation in southwestern Japan, representing the easternmost fossil record of ceratopsians in Asia. Sasayamagnomus exhibits three diagnostic features in the jugal, squamosal and coracoid, respectively, and also has a unique combination of characters in the lacrimal. Our phylogenetic analysis indicates that Sasayamagnomus forms a clade with Aquilops americanus, one of the earliest neoceratopsians from North America, followed by the sister taxon Auroraceratops rugosus from China. The present time‐calibrated phylogenetic tree indicates that the immigration of neoceratopsians from Asia to North America occurred during the latest Aptian or early Albian, refining the previously suggested timeframe. This aligns with fragmentary neoceratopsian fossil records from the Lower Cretaceous of North America and the initial formation of the Bering land bridge. Furthermore, the simultaneous occurrence of global warming (which enabled the development of extensive forests in the Arctic region) and the emergence of the Bering land bridge during the Aptian–Albian, probably played a crucial role in facilitating the immigration of neoceratopsians from Asia to North America.
  • 坂本拓海, 池田忠広, 実吉玄貴, 髙橋 亮雄, 石垣 忍
    岡山理科大学 古生物学・年代学研究センター事業報告, (4) 59-61, Mar, 2024  
  • Tomonori Tanaka, Kazumi Wada, Akiko Shinya, Tadahiro Ikeda
    Palaeontologia Electronica, 27(1) 1-19, Jan, 2024  Peer-reviewedLast author
  • Shinobu ISHIGAKI, Khishigjav TSOGTBAATAR, Buuvei MAINBAYAR, Akio TAKAHASHI, Batsaikhan BUYANTEGSH, Mototaka SANEYOSHI, Jargalsaikhan BATSUKH, Kazumasa AOKI, Tomohiko SAT, Battulga BILGUUNBOLD, Tadahiro IKEDA, Hiroyuki YAMASHITA, Jun, OSHITANI, Shoji HAYASHI, Ryuji TAKASAKI, Kentaro CHIBA
    The bulletin of Research Institute of Frontier Science and Technology, 5 7-11, Dec 28, 2023  
  • Nana Watanabe, Kohsaku Arai, Makoto Otsubo, Mamoru Toda, Atsushi Tominaga, Shun Chiyonobu, Tokiyuki Sato, Tadahiro Ikeda, Akio Takahashi, Hidetoshi Ota, Yasufumi Iryu
    Progress in Earth and Planetary Science, 10(1), Jul 20, 2023  Peer-reviewedInvited
    Abstract The modern and Late Pleistocene terrestrial fauna of Miyako Jima and adjacent islands (the Miyako Islands) in the southern Ryukyu Islands, southwestern Japan, includes some endemic taxa or genetically unique populations that exclusively have closest allies in the more isolated Okinawa Jima and adjacent islands (the Okinawa Islands) than in the Yaeyama Islands, which are located southwest of the Miyako Islands with much narrower intervening straits. Those taxa or populations include representatives of lineages that have physiologically highly limited ability for over-sea dispersal and the Miyako Islands are currently separated from the Okinawa Islands by at least 300 km of open water; therefore, the formation of this phylogeographical pattern is perplexing. In this study, we review the late Cenozoic geology of the Miyako Islands, southern Okinawa Jima, the Okinawa–Miyako submarine plateau (OMSP; a plateau located between Okinawa Jima and Miyako Jima), and the Kerama gap, which is a depression between the OMSP and Okinawa Jima. We then consider the origin of the modern and Late Pleistocene terrestrial animals, including a number of non-volant vertebrates on the Miyako Islands. Finally, we propose a new hypothesis (the OMSP hypothesis) to explain the enigmatic composition of modern and Late Pleistocene terrestrial vertebrate fauna of the islands. Southern Okinawa Jima was uplifted and emerged after ca. 2 Ma and was temporarily connected to the OMSP, which is likely to have emerged earlier than southern Okinawa Jima, to form a large island extending from Okinawa Jima to the Miyako Islands with a NE–SW direction of ~ 400 km. Subsequently, Okinawa Jima became separated from the OMSP when the Ryukyu Group—which is composed of Quaternary reef and associated fore-reef and shelf deposits—began to accumulate around the island at 1.7–1.4 Ma. During the interval from 2.0 to 1.7–1.4 Ma, numerous terrestrial animals, including flightless vertebrates, extended their distribution to the OMSP. Although the Miyako Islands repeatedly underwent complete submergence during deposition of the main part of the Ryukyu Group (1.25–0.4 Ma), they were uplifted and emerged to become a land area after ca. 0.4 Ma. In contrast, the OMSP subsided after ca. 0.4 Ma and was almost completely submerged after 0.27 Ma. During ca. 0.4–0.27 Ma, terrestrial animals migrated from the OMSP to the Miyako Islands.

Misc.

 64

Books and Other Publications

 3

Presentations

 70

Teaching Experience

 4

Professional Memberships

 4

Research Projects

 9

Academic Activities

 19

Social Activities

 34

Media Coverage

 8