Rediscovery of type specimens of Nesorhinus hayasakai (Mammalia, Rhinocerotidae) from the Pleistocene of Taiwan

Historically, the excavation in the 1970s and publication in the 80s of Rhinoceros sinensis hayasakai (now known as Nesorhinus hayasakai) represents a milestone in vertebrate paleontology in Taiwan. However, the type materials (including 22 syntypes) are missing after the 1984 publication due to the lack of proper curation and management, and reflect the undervalued vertebrate paleontology in Taiwan. Here we found five original specimens out of 22 in two collections (National Taiwan University and Tainan City Zuojhen Fossil Park). The original 22 specimens were recovered from two geographical localities and geological horizons: northern (Taoyuan, Tunghsiao Formation: Early Pleistocene) and southern (Tainan, Chiting Formation: Middle Pleistocene) Taiwan. Our rediscovery of long-forgotten type materials emphasizes the importance of proper specimen curation. Similarly, by clarifying the historical issues and collecting more fossils, vertebrate paleontology from Taiwan promises to offer novel perspectives to understand the origin of modern biodiversity and large-scale extinctions along the eastern margin of Eurasia.