Investigation of sexual dimorphism in fossil organisms

2022 Fiscal Year Final Research Report

• Project/Area Number: 19K14831
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 17050:Biogeosciences-related
• Research Institution: Okayama University of Science
• Principal Investigator: Chiba Kentaro 岡山理科大学, 生物地球学部, 講師 (80826438)
• Project Period (FY): 2019-04-01 – 2023-03-31
• Keywords: 恐竜

Outline of Final Research Achievements

This study investigated methods for distinguishing sexual differences in fossil animals based on osteohistological techniques using ceratopsian dinosaurs, which have prominent ornamentation and are represented by large sample sizes of available specimens. This study suggested that sexual differences might be observed in the ornamentations along with variations in body size in Centrosaurus and Protoceratops. Moreover, through this investigation, several important features in the classification of ceratopsians were identified. While there are many groups of dinosaurs characterized by various ornamentations, the existence of sexual dimorphism has been a matter of debate. In the future, it might be possible to clarify the presence of sexual differences in dinosaurs based on osteohistological investigations.

Free Research Field

古生物学

Academic Significance and Societal Importance of the Research Achievements

現生動物では角やとさか等の構造に性差が見られることが多い。性差は主に性選択により発達し、種分化・形態的多様性に深く関連している。化石動物の中にも同様の装飾構造を持つものが多くいたが，これらの構造に性差が見出されることは極めて稀であり、性選択以外のプロセスでこれらの構造が進化したとする仮説も提唱されている．しかし，本研究の結果骨組織学的に標本の成長段階を推定し、成体個体のみにおいて性差の検討を行うことで、化石種でも性差を認識することができる可能性が示された。これにより、化石種のマクロ進化において見過ごされている性選択の重要性を再評価することが可能となると期待される。