Palaeoloxodon huaihoensis

Palaeoloxodon huaihoensis is an extinct species of elephant belonging to the genus Palaeoloxodon known from the Pleistocene of China.

Taxonomy
It was first named a subspecies of P. naumanni (which is principally known from material found in Japan) by J. Liu in 1977 based on a partial skeleton from Huaiyuan, Anhui, and was later elevated to species rank by G. Qi in 1999, who also included other Chinese Palaeoloxodon remains within species, including the abundant remains found in the Penghu Channel between the Penghu archipelago and Taiwan. Material from the Pengu Channel sample predominantly represents adult individuals. A mostly complete adult skull (IVPP V4443) from Late Pleistocene Nihewan basin in Hebei may be referrable to this species.

Description
The body size is very large, comparable to Indian Palaeoloxodon namadicus and the European straight-tusked elephant (P. antiquus), with specimens from the Penghu Channel and Taiwan estimated to reach shoulder heights of over 4 m and body masses over 10 tonnes. In comparison to Indian P. namadicus, the postcranial skeleton is substantially more robust, and greatly resembles that of P. antiquus. The morphology of IVPP V4443 is also overall more similar to that of P. antiquus than P. namadicus, but the parietal-occipital crest at the top of the skull displays a very robust morphology closer to that of P. namadicus.

Distribution
Remains of Palaeoloxodon are widespread in China, ranging from Northeast China to Xinjiang in the northwest to Hainan and Yunnan in the south, though most remains of Palaeoloxodon in China are from the North China Plain region.

Evolution and extinction
The oldest remains of Palaeoloxodon in North China date to the early Middle Pleistocene, around 700,000 years ago. The latest dates for Palaeoloxodon in China are from the Late Pleistocene, and a Holocene survival is not substantiated, though the actual timing of extinction is uncertain due to a lack of reliable dating. Mitochondrial genomes retrieved from Chinese Palaeoloxodon individuals from North China reveal that like the European P. antiquus, they harboured mitochondrial lineages derived from those of African forest elephants as a result of hybridisation with that species prior to Palaeoloxodon leaving Africa. The close relationship between the mitochondrial genomes of a Chinese Palaeoloxodon and a European P. antiquus individual suggests that there may have been gene flow between the two populations following their initial divergence.

Diagram of the relationships of elephant mitochondrial genomes, after Lin et al. 2023.