Preservation of luminescent organs in the Miocene deep-sea lanternfish fossils

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K03827
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 17050:Biogeosciences-related
• Research Institution: Kyushu University
• Principal Investigator: MAEDA Haruyoshi 九州大学, 総合研究博物館, 教授 (10181588)
• Co-Investigator(Kenkyū-buntansha): 田中 源吾 金沢大学, GS教育系, 助教 (50437191)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: タフォノミー / 師崎層群 / 深海魚化石 / 発光器 / メラノソーム

Outline of Final Research Achievements

The preservation of luminescent organs of lantern fish fossils from the Miocene Morozaki Formation in Aichi Prefecture, Japan, was carefully examined from the viewpoint of taphonomy. As a result of introducing "infrared-" and "ultraviolet photography", the traces of soft parts and the shape of luminescent organs, which could not be identified by conventional visible light observation, were clearly captured. SEM, TEM, and TOF-SIMS analyses revealed that the shape and original arrangement of the focusing lens, reflector (tapetum), and pigment particles were preserved in the fossils. In addition, melanosomes are preserved in some of the tapetums. This is the first example of a light-absorbing tissue containing the pigment melanin, which means that the original organic material of the luminescent organ may have been preserved.

Free Research Field

層位・古生物学

Academic Significance and Societal Importance of the Research Achievements

従来，海外に比べて日本は化石の保存が悪いといわれ，その分，化石鉱脈と呼ばれる軟体部保存を示す例外的な化石の研究において西欧諸国の後塵を拝していた．今回，約1,600万年前の師崎層群産の深海魚化石が発光器の痕跡を保っていることを明らかにし，世界的に著名な化石鉱脈に匹敵するレベルの化石鉱脈が日本にも存在することを示した．これは，変動帯に位置する日本固有の化石鉱脈の研究が有望であることを示したものといえる．