A glimpse into a vanished ecosystem: reconstructing diet and palaeoenvironment of Palaeoloxodon from the Pleistocene of Taiwan.

Palaeoloxodon is the largest known terrestrial mammal in the history of Taiwan. However, little is known about the palaeoecology and palaeoenvironment of these extinct proboscideans. In this study, we investigate the stable carbon and oxygen isotopic ratios of sequential enamel samples taken along the growth direction of molars from three Palaeoloxodon specimens of different ontogenetic ages from the Pleistocene of Taiwan. Our results suggest that these proboscideans relied extensively on a C4 diet, a dietary niche distinct from the Eurasian Palaeoloxodon antiquus but similar to the predominantly C4-grazing species Palaeoloxodon namadicus. The specimens show depleted δ 18O values, indicating obligate drinking and reliance on running water sources, such as monsoon-fed rivers, which exhibit more depleted δ 18O values. Additionally, the juvenile specimen shows an isotopic shift in both δ 13C and δ 18O values, aligning with the known signals of weaning in proboscideans. This could provide a novel insight into the life history and weaning age of Palaeoloxodon. Our results highlight, to our knowledge, the first evidence of a unique palaeohabitat of Palaeoloxodon from the Pleistocene of Taiwan, represented by C4 vegetation and the presence of a palaeo-river system that supported these giant proboscideans.