台灣南部更新世真鹿屬化石之分類修訂與鹿角種內變異

Abstract

鹿角是鹿科動物獨有的雄性性徵，亦是該類群、尤其化石物種分類的核心依據。然而，若缺乏與現生物種的系統性比較，種內形態差異極易被誤判為物種診斷特徵，此現象在多樣性高的化石真鹿屬（Cervus)中尤為顯著。本研究描述了產自台灣台南中更新世地層的真鹿屬鹿角和頭骨化石，透過特徵鑑定、形態比較及量化數據分析，釐清1978年所記錄的台南真鹿屬未定種（Cervus sp.）分類地位。結果顯示，該台南真鹿屬化石紀錄應為梅花鹿（C. nippon），惟其生長軌跡與現生台灣梅花鹿有所差異。此外，結合線性測量數據、地質學與分子生物學等多重證據，本研究發現化石種葛氏斑鹿（C. grayi）的診斷特徵均落在梅花鹿的種內變異範圍內，支持了過去研究對該物種有效性的質疑，據此推測過往紀錄之葛氏種紀錄應代表生存於早更新世至晚更新世的梅花鹿化石種群，且至少於中更新世時便已擴散至台灣。值得注意的是，線性測量與幾何形態分析之結果呈現出不同的分類解讀，反映出研究方法的選用可能會影響分類的結果。本研究不僅釐清了台灣真鹿屬化石紀錄與葛氏斑鹿的分類地位及演化史，更揭示了鹿科動物分類研究中評估現生物種之種內變異之必要，以提升分類的可靠性。

Antlers, a distinctive trait of cervids, serve as crucial diagnostic features for taxonomic identification, especially for fossil species where skeletal remains are limited. However, without systematic comparison with extant species, intraspecific variation may be misinterpreted as species-specific diagnostic characteristics. This issue is particularly profound in fossil Cervus species, which exhibit high morphological diversity across Eurasia. In this study, we describe fossil antlers and a skull of Cervus from the Middle Pleistocene of Tainan, Taiwan, and clarify the taxonomic status of the Cervus sp. reported in 1978, which has remained unresolved due to limited evidence. Based on key diagnostic features, detailed morphological comparisons, and quantitative analyses using both fossil specimens and extant C. nippon specimens, our study indicates that these fossils belong to the extant species C. nippon, representing a distinct population with a unique developmental pattern. Furthermore, by integrating quantitative datasets with molecular and geological evidence, our findings reveal that the antler characteristics of the fossil species C. grayi fall within the range of intraspecific variation observed in C. nippon, supporting prior taxonomic skepticism and aligning with the hypothesis of invalidity. We speculate that specimens previously assigned to “C. grayi” instead represent Pleistocene populations within the morphological variation of C. nippon, which may have occurred in Taiwan as early as the Middle Pleistocene. Notably, linear, and geometric morphometric analyses yielded different results, highlighting the influence of analytical methods on taxonomic conclusions. Overall, our study not only elucidates the taxonomy and evolutionary history of C. grayi and fossil Cervus in Taiwan, but also emphasizes the importance of considering intraspecific variation in extant species to enhance taxonomic robustness.