https://scholars.lib.ntu.edu.tw/handle/123456789/637385
標題: | A new Pleistocene physeterid specimen from the Kazusa Group in the western part of Kanto Plain and a review of the fossil cetaceans from the Pleistocene of Japan | 其他標題: | 西部上総層群産クジラ類化石の概要と更新統における鯨類相 | 作者: | Kimura, Toshiyuki Taru, Hajime CHENG-HSIU TSAI |
關鍵字: | Cetacea | Kazusa Group | Physeter sp | Physeteridae | Pleistocene | 公開日期: | 30-九月-2023 | 出版社: | Palaeontological Society of Japan | 卷: | 114 | 起(迄)頁: | 37-45 | 來源出版物: | Fossils | 摘要: | This study describes a previously undescribed fossil physeterid from the Pleistocene of Tokyo. This fossil physeterid was recovered from the Early Pleistocene, Fukushima Formation (ca. 1.60‒1.77 Ma), Kazusa Group in 1971 and has long been known as “Hino Kujira” without detailed descriptions. The specimen consists of fragments of the left maxilla, and we estimate the original size of the maxilla can reach at least 3 m long, suggesting an individual at least 11.5 m long. The maxilla is dorsoventrally thick (eroded, but at least 188 mm), and such a thick maxilla clearly differs from that of mysticetes but is similar to that of the modern sperm whale, Physeter macrocephalus. In addition, the average size of each pore on the spongy bone under the compact bone layer is prominent (10 to 15 mm in diameter), consistent with the macroporous structure of the maxilla of modern Physeter macrocephalus. We then provisionally make the taxonomic assignment of this Pleistocene specimen as Physeter sp. Besides, we review seventy-three documented fossil cetaceans from the Pleistocene of Japan, suggesting that the known paleodiversity of the Japanese Pleistocene cetaceans (12 genera) is much lower than that of modern composition (26 genera). This evident discrepancy likely results from the research effort that currently only produces an inadequately known fossil record of cetaceans. |
URI: | https://scholars.lib.ntu.edu.tw/handle/123456789/637385 | ISSN: | 00229202 | DOI: | 10.14825/kaseki.114.0_37 |
顯示於: | 生命科學系 生命科學系 |
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