Crocodylian princess in Taiwan: Revising the taxonomic status of Tomistoma taiwanicus from the Pleistocene of Taiwan and its paleobiogeographic implications

Toyotamaphimeia is an extinct crocodylian lineage whose name is derived from a mythological Japanese princess. Here, we reexamine the type specimens of a long-forgotten species: Tomistoma taiwanicus from the Pleistocene of Tainan (Taiwan) and revise its taxonomic status to Toyotamaphimeia taiwanicus comb. nov., leading to the first recognized species of Toyotamaphimeia outside Japan. Our phylogenetic analyses also support this taxonomic assignment and, more interestingly, further suggest an East Asian lineage. In addition, Toyotamaphimeia taiwanicus represents a tropical species, resolving a long-lasting puzzle of why Toyotamaphimeia only inhabited the much higher latitudinal area (Japan). Given the large body size of Toyotamaphimeia taiwanicus (about 7 m) and the fact that it is geologically older than Toyotamaphimeia machikanensis from Japan, we propose a novel evolutionary scenario: the genus Toyotamaphimeia originated in Taiwan and evolved to a large body size with gigantothermic physiology, allowed an Out-of-Taiwan scenario, and dispersed further north to Japan. Our taxonomic identification shows the presence of an extinct endemic crocodylian species from the Pleistocene of Taiwan with large-scale paleogeographic implications, and this study, with our recent progress in vertebrate paleontology in Taiwan, should provoke more in-depth paleontological research on the Pleistocene extinction.