Palaeoloxodon namadicus is an extinct species of prehistoric elephant known from the Middle Pleistocene to Late Pleistocene of the Indian subcontinent, and possibly also elsewhere in Asia. The species grew larger than any living elephant, and is one of the largest known proboscideans alongside the mastodon "Mammut" borsoni. Speculative estimates based on a lost, fragmentary, femur – measured in the 19th century – has led some authors to suggest that P. namadicus may have been larger than Paraceratherium, generally considered the largest known land mammal ever.
Taxonomic history Remains now recognised as belonging to P. namadicus were unearthed during the rule of the British East India Company in India by Dr George Green Spilsbury at least as early as the 1830s. The species was named as Elephas namadicus by British paleontologists Hugh Falconer and Proby Cautley in 1846, based on a skull collected from the valley of the Godavari River in central India. In 1924, American paleontologist Henry Fairfield Osborn placed it within the newly coined genus Sivalika. Also in that year, Japanese paleontologist Matsumoto Hikoshichirō placed it within his newly coined subgenus Palaeoloxodon, which he placed within Loxodonta (which contains the living African elephants), with the type species being the Japanese Loxodonta (Palaeoloxodon) naumanni, which had previously been named also in 1924 as a subspecies of P. namadicus. In his posthumous 1942 monograph, Osborn placed the species within Palaeoloxodon, which he regarded as a genus in its own right rather than as a subgenus, with both positions widely supported by modern authors. A number of authors, including Vincent J. Maglio in his widely referenced 1973 work Origin and Evolution of the Elephantidae, have historically regarded P. namadicus and the largely European straight-tusked elephant (P. antiquus) as the same species due to their similar skull and tooth morphology. This was questioned by later authors and the two species are now generally considered distinct.
Description
P. namadicus shares similarities to other species of Palaeoloxodon, which includes a large growth of bone (the parieto-occipital crest) at the top of the skull that overhangs the forehead region, which likely anchored the splenius muscles used to support the head. This structure is more developed in males than in females. Recent research has suggested that P. namadicus can be distinguished from P. antiquus by its less robust (proportionally more slender) limb bones and more stout cranium (including a better developed parieto-occipital crest), and the presence of a teardrop shaped indentation/depression in the infraorbital region behind the eyesocket not found in P. antiquus. Palaeoloxodon turkmenicus, also known from the Indian subcontinent, is distinguished from P. namadicus by its much more weakly developed parietal-occipital crest. Like other large Palaeoloxodon species, the tusks of P. namadicus were proportionally large, though no complete tusks are known. One partial tusk was estimated to be 3.66 metres (12.0 ft) long and over 120 kilograms (260 lb) in weight when complete, larger than the largest recorded African bush elephant tusk.
Size
Like living elephants, Palaeoloxodon namadicus is thought to have been sexually dimorphic, with males considerably larger than females, with the skull of a P. namadicus male found in the Godavari valley described in 1905 being a full 40% larger than that of a mature female (NHMUK PV M3092, which is now the lectotype specimen from which the species is defined). Palaeoloxodon namadicus is the largest species in the genus Palaeoloxodon and one of the largest known proboscideans along with the mastodon "Mammut" borsoni, and considerably larger than living elephants. A 2015 study by Asier Larramendi attempted to estimate the size of P. namadicus, as well as other prehistoric proboscideans. Based on a fragmentary skeleton of an adult male, comprising two femurs (the left one of which was measured to be 1.6 metres (5.2 ft) in length when excavated in 1834), a left ulna and a right humerus, from Sagauni in Narsinghpur district, Madhya Pradesh, Larramendi extrapolated a shoulder height of 4.35 metres (14.3 ft) and a weight of 13 tonnes (29,000 lb) for this individual.
A fragmentary lower portion of a femur described in 1834 in the same publication that described the femurs of the Sagauni specimen, stated that this femur was almost a quarter larger than that from Sagauni. Assuming it was about 20% larger, Larramendi calculated an extrapolated femur length of 1.9 metres (6.2 ft) and a speculative size estimate of 5.2 m (17 ft 1 in) tall at the shoulder and 22 tonnes (49,000 lb) in body mass, which if correct would make P. namadicus possibly the largest land mammal ever, exceeding even paraceratheres in size (the largest specimens of Paraceratherium transouralicum were estimated to weigh 17.1 tonnes (38,000 lb) in the same study). However, Larramendi stated that this estimate should be "taken with a grain of salt" (treated with caution), as they could not locate the specimen, but speculated that it may be stored in the Indian Museum of Kolkata.In 2023, a publication by Gregory S. Paul and Larramendi estimated that another specimen identified as cf. P. namadicus, also only known from a partial femur, would have weighed 18–19 tonnes (40,000–42,000 lb). Other authors have noted that weight estimates for proboscideans based on single bones can lead to estimates that are "highly improbable" compared to accurate estimates from complete skeletons. In 2024, Biswas, Chang and Tsai estimated a maximum shoulder height of 4.51 metres (14.8 ft) and body masses between 13.22 to 18.47 tonnes (29,100 to 40,700 lb) for 5 specimens of P. namadicus from the Indian subcontinent. including supplemental table S4
Ecology
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