Palaeoloxodon namadicus

''Palaeoloxodon namadicus'' or the Asian straight-tusked elephant, is an extinct species of prehistoric elephant known from the early Middle to Late Pleistocene of the Indian subcontinent, and possibly also elsewhere in Asia.

Some authorities regard it to be a subspecies of '' Palaeoloxodon antiquus'', the European straight-tusked elephant, due to extreme similarities of the tusks. Their skull structure was also different from that of a modern elephant. The grouping of this genus is supported by cranial synapomorphies with other species of ''Palaeoloxodon,'' which includes a large crest at the top of the skull that anchored the splenius muscles used to support the head. Later research suggested that ''P. namadicus'' can be distinguished from ''P. antiquus'' by its less robust limb bones and more stout cranium.

Based on the stable isotope ratioes of carbon and oxygen and the morphology of their teeth, it is suggested that ''P. namadicus'' tended towards a grazing diet, as opposed to the sympatric ''Stegodon'' and '' Elephas'' species, which tended more towards browsing.

''Palaeoloxodon namadicus'' is thought to have become extinct during the Late Pleistocene, making it one of four megafaunal species native to India known to have become extinct during the Late Pleistocene, alongside fellow proboscidean '' Stegodon namadicus'', the equine '' Equus namadicus'', and a species of hippopotamus belonging to the genus ''Hexaprotodon''. A late record of approximately 56,000 years Before Present is known from the banks of the Dhasan River on the Ganga plain in Uttar Pradesh. In 2015, a study based on extensive research of fragmentary leg bone fossils suggested that ''P. namadicus'' may have been the largest land mammal ever, but this requires reexamination.

Remains possibly attributable to ''P. namadicus'' have also been reported across Southeast Asia and China. However, the status of Chinese ''Palaeoloxodon'' is unresolved, with other authors considering the remains to belong to ''P. naumanni'' (otherwise known from Japan) or the separate species '' P. huaihoensis''. The postcranial remains of ''Palaeoloxodon'' from China are substantially more robust than Indian ''P. namadicus'' and in many respects are more similar to those of ''P. antiquus''. Remains attributed to ''P. namadicus'' or a similar form have been reported from the island of Sulawesi in Indonesia, similar in size to that reported for the Indian subcontinent.

Size

Several studies have attempted to estimate the size of the Asian straight-tusked elephants, as well as other prehistoric proboscideans, usually using comparisons of thigh bone length and knowledge of relative growth rates to estimate the size of incomplete skeletons.

One partial skeleton found in India in 1905 had thigh bones that likely measured when complete, suggesting a total shoulder height of for this individual elephant.

Two partial thigh bones were found in the 19th century and would have measured 160 cm (5.2 ft) when complete. A fragment from the same locality was said to be almost a quarter larger; volumetric analysis then yields a size estimate of tall at the shoulder and in body mass; however, this estimate based on the "distal femur portion" requires reexamination, as the author himself could only suspect that "fossils are likely stored in the Indian Museum of Kolkata; until such a collection can be revised, this size estimate will remain speculative."

References

{{Taxonbar, from=Q7126427

Palaeoloxodon
Pleistocene proboscideans
Pleistocene mammals of Asia
Taxa named by Hugh Falconer
Fossil taxa described in 1846