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 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 Penghu Channel sample predominantly represents adult individuals. A mostly complete adult skull 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, and much larger than Japanese specimens of Palaeoloxodon naumanni, with specimens from the Penghu Channel and Taiwan estimated to reach shoulder heights of over and body masses over. While historically Chinese Palaeoloxodon remains were attributed to Palaeoloxodon namadicus, Chinese Palaeoloxodon remains display notable anatomical differences from Indian P. namadicus. 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. Chinese Palaeoloxodon skulls also lack the infraorbital depression behind the eye socket found in P. namadicus individuals.

Distribution and ecology

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.
In Late Pleistocene northern China, Palaeoloxodon co-occurred alongside the giant deer Sinomegaceros ordosianus, Merck's rhinoceros, the woolly rhinoceros the buffalo Bubalus wansijocki, aurochs, the Asiatic wild ass, goitered gazelles the camel Camelus knoblochi, cave hyenas, tigers, and Przewalski's horse-like horses.
In Penghu Channel deposits, remains of Palaeoloxodon co-occur alongside those of cave hyenas, tigers, brown bears, raccoon dogs wild horses, the extinct buffaloes Bubalus teilhardi and Bubalus youngi, Père David's deer , deer belonging to the genus Cervus, pigs,^{supplemental material} as well as Denisovan archaic humans. During glacial periods when the sea level was much lower than today, what is now the Penghu Channel is thought to have been a lowland area of grassland dominated by plants with C₄-type carbon fixation. Isotopic analysis of Penghu Palaeoloxodon specimens suggests that they had a C₄ grass-heavy diet, similar to Indian P. namadicus, but in contrast to the European straight-tusked elephants, which incorporated much more browse into their diet.

Evolution and extinction

The oldest remains of Palaeoloxodon in North China date to the early Middle Pleistocene, around 700,000 years ago. 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. In the early 2020s, it became suggested by some authors that Chinese Palaeoloxodon should be considered the same species as the European straight-tusked elephant Palaeoloxodon antiquus, given their very similar morphology.
Diagram of the relationships of elephant mitochondrial genomes, after Lin et al. 2023.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.