Fish fossils of Taiwan: a review and prospection

Despite the frequent occurrence of fish fossils in the field, related studies are noticeably rare in Taiwan. The scant fossil record of fish in the literature sharply contrasts the high diversity of modern fish in this region. This is often due to the scarcity of well-preserved materials, limited exposure that covers long geological ages, and lack of comprehensive sampling design. Over the years, unstudied new fish fossils have been collected and accumulated. Several old and published specimens stored in private collections are lost. In this study, we evaluated potential horizons yielding fish fossils, examined the current status of published specimens with updated regional stratigraphic correlation, and finally explored possible directions for future work. Our extensive bibliographic reviews revealed a total of published 47 taxa, which are mostly in the form of teeth (elasmobranch) and otoliths (teleost). Skeletal specimens with taxonomic value are rare. Using Plio-Pleistocene otoliths from the famous Chochen-Tsailiao locality, we further demonstrated that they are numerous in the sediments, with high abundance and broad distribution. Study small fish remains for attaining a high resolution on the spatiotemporal dynamics of fish faunas through time and for providing the data necessary for conservational purposes is recommended.

尽管野外鱼类化石的产出较为普遍，但台湾地区的相关研究却明显匮乏。文献记载的鱼类化石记录稀缺，与该区域现代鱼类的高度多样性形成鲜明反差。这种现象通常源于三方面因素：保存储存完好的化石材料稀少、覆盖较长地质年代的露头有限，以及缺乏系统性的综合采样设计。多年来，尚未被研究的新鱼类化石标本持续被采集并累积，而馆藏于私人收藏机构的部分已发表旧标本则已遗失。本研究首先评估了产出鱼类化石的潜在层位，结合最新的区域地层对比工作梳理了已发表标本的当前现状，并最终探讨了未来研究的可行方向。通过全面的文献调研，我们共梳理出47个已发表的鱼类化石类群，其中绝大多数以板鳃类（elasmobranch）牙齿和真骨鱼类（teleost）耳石的形式保存。具有分类学价值的骨骼标本则极为罕见。以著名的草岭-菜寮（Chochen-Tsailiao）产地的上新世-更新世（Plio-Pleistocene）耳石标本为例，我们进一步证实这类化石在沉积物中数量丰富、丰度颇高且分布广泛。本研究建议，针对小型鱼类遗骸开展深入研究，以期精准解析鱼类群落在时间尺度上的时空动态，并为鱼类保护相关研究提供必要的数据支撑。