[論文] 直良コレクションの葛生産オオカミ標本の放射性炭素(14C)年代測定による生息年代の決定と日本列島のオオカミの下顎第一臼歯の大きさの経時的変化について

• Main Authors: 甲能, 純子, コウノ, アヤコ, KOHNO, Ayako, 茂原, 信生, シゲハラ, ノブオ, SHIGEHARA, Nobuo, 門叶, 冬樹, トカナイ, フユキ, TOKANAI, Fuyuki, 工藤, 雄一郎, クドウ, ユウイチロウ, KUDO, Yuichiro, 甲能, 直樹, コウノ, ナオキ, KOHNO, Naoki
• Format: Other/Unknown Material
• Language: Japanese
• Published: 国立歴史民俗博物館 2023
• Subjects: 14C 年代測定; 更新生オオカミ; ニホンオオカミ; 下顎第１臼歯; 直良コレクション; Nobuo Naora collection; 14C-dating method; Pleistocene wolves; Japanese wolves; Lower first molars; Canis lupus
• Online Access: https://rekihaku.repo.nii.ac.jp/record/2000036/files/kenkyuhokoku_243_05.pdf

国立歴史民俗博物館に収蔵されている（故）直良信夫収集の栃木県佐野市葛生から産出したオオカミ（Canis lupus sspp.）の標本4点について，加速器質量分析計（AMS）による放射性炭素（14C）年代測定を行って，それぞれの個体の生息年代を明らかにした。また，14C年代測定によって年代が明らかとなった更新世以降の日本列島のオオカミを，個々の正確な生息年代で時間軸上に並べ，それぞれの下顎第一臼歯の近遠心径の大きさを指標として経時的な変化の様相を検討した。その結果，更新世の化石オオカミと現生ニホンオオカミとの間には明らかな大きさの相違と時間軸上での不連続が認められ，ニホンオオカミは更新世オオカミが小型化した「直系子孫」とは考えにくく，さらなる検証が必要であるとの結論を得た。 The radiocarbon (14C) age for four wolf specimens (NMJH A-636-1-1-18-1, A-636-1-1-18-4, A-636-1-1-19-1, and A-636-1-2-41-2) that were collected by Nobuo Naora in 1940s-1960s from the fissure deposits in Kuzuu, Sano City, Tochigi Prefecture in the Nobuo Naora’s collection at The National Museum of Japanese History were measured by Accelerated Mass Spectrometry (AMS). As a result, NMJH A-636-1-1-18-1 was unmeasurable as over background, suggesting that it was thought to be of the middle Late Pleistocene or much older in age: in fact it was strongly fossilized. NMJH A-636-1-1-18-4 was initially thought to be of the period between the latest Early Pleistocene and the Middle Pleistocene by Naora himself, but it was measured as the late Late Pleistocene (33645 ±238 BC). NMJH A-636-1-1-19-1 was also initially thought to be the same age as NMJH A-636-1-1-18-4, but it turned out to be a slightly older than the previous thought, i.e., the late Late Pleistocene (35626±481 BC). NMJH A-636-1-2-41-2 had long been thought to be from the Kofun Period (Mid 3rd century or 7th century) by Naora, but it was measured as an age of the Middle Jomon period (5008±74 BC). In addition, fossils and remains of wolves from the Japanese Archipelago after the late Late Pleistocene (younger than 50 Ka), whose ages were revealed by 14C dating, were compared based on the size of the lower first molar (M1) through time, and the mesiodistal diameters of each M1 were compared with each other to consider the chronological changes of their sizes. As a result, discontinuity of the M1 size between the fossils older than 12 Ka and the remains younger than 12 Ka was recognized. Furthermore, comparing the proportion ...