''Palaeoloxodon namadicus'' or the Asian straight-tusked elephant, is an extinct
species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
of prehistoric elephant known from the early
Middle to
Late Pleistocene
The Late Pleistocene is an unofficial Age (geology), age in the international geologic timescale in chronostratigraphy, also known as Upper Pleistocene from a Stratigraphy, stratigraphic perspective. It is intended to be the fourth division of ...
of the
Indian subcontinent
The Indian subcontinent is a list of the physiographic regions of the world, physiographical region in United Nations geoscheme for Asia#Southern Asia, Southern Asia. It is situated on the Indian Plate, projecting southwards into the Indian O ...
, and possibly also elsewhere in Asia.
![Palaeoloxodon namadicus-bpk](https://upload.wikimedia.org/wikipedia/commons/c/ce/Palaeoloxodon_namadicus-bpk.jpg)
Some authorities regard it to be a
subspecies
In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...
of ''
Palaeoloxodon antiquus
The straight-tusked elephant (''Palaeoloxodon antiquus'') is an extinct species of elephant that inhabited Europe and Western Asia during the Middle and Late Pleistocene (781,000–30,000 years before present). Recovered individuals have reac ...
'', 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
''Palaeoloxodon'' is an extinct genus of elephant. The genus originated in Africa during the Pliocene era, and expanded into Eurasia during the Pleistocene era. The genus contains some of the largest known species of elephants, over four metres t ...
,'' which includes a large crest at the top of the skull that anchored the
splenius muscles
The splenius muscles are:
*Splenius capitis muscle
*Splenius cervicis muscle
Their origins are in the upper thoracic and lower cervical spinous process
The spinal column, a defining synapomorphy shared by nearly all vertebrates,Hagfish are ...
used to support the head. Later research suggested that ''P. namadicus'' can be distinguished from ''P. antiquus'' by its less
robust
Robustness is the property of being strong and healthy in constitution. When it is transposed into a system, it refers to the ability of tolerating perturbations that might affect the system’s functional body. In the same line ''robustness'' ca ...
limb bones and more stout cranium.
Based on the
stable isotope ratio
The term stable isotope has a meaning similar to stable nuclide, but is preferably used when speaking of nuclides of a specific element. Hence, the plural form stable isotopes usually refers to isotopes of the same element. The relative abundanc ...
es of carbon and oxygen and the morphology of their teeth, it is suggested that ''P. namadicus'' tended towards a
grazing
In agriculture, grazing is a method of animal husbandry whereby domestic livestock are allowed outdoors to roam around and consume wild vegetations in order to convert the otherwise indigestible (by human gut) cellulose within grass and other ...
diet, as opposed to the sympatric ''
Stegodon
''Stegodon'' ("roofed tooth" from the Ancient Greek words , , 'to cover', + , , 'tooth' because of the distinctive ridges on the animal's molars) is an extinct genus of proboscidean, related to elephants. It was originally assigned to the famil ...
'' and ''
Elephas
''Elephas'' is one of two surviving genera in the family of elephants, Elephantidae, with one surviving species, the Asian elephant, ''Elephas maximus''.
Several extinct species have been identified as belonging to the genus, extending back to ...
'' species, which tended more towards
browsing
Browsing is a kind of orienting strategy. It is supposed to identify something of relevance for the browsing organism. When used about human beings it is a metaphor taken from the animal kingdom. It is used, for example, about people browsing o ...
.
''Palaeoloxodon namadicus'' is thought to have become
extinct
Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...
during the
Late Pleistocene
The Late Pleistocene is an unofficial Age (geology), age in the international geologic timescale in chronostratigraphy, also known as Upper Pleistocene from a Stratigraphy, stratigraphic perspective. It is intended to be the fourth division of ...
, making it one of four megafaunal species native to India known to have become extinct during the Late Pleistocene, alongside fellow
proboscidea
The Proboscidea (; , ) are a taxonomic order of afrotherian mammals containing one living family (Elephantidae) and several extinct families. First described by J. Illiger in 1811, it encompasses the elephants and their close relatives. From ...
n ''
Stegodon namadicus'', the equine ''
Equus namadicus
''Equus namadicus'' is a prehistoric equid, known from remains dating to the Middle and Late Pleistocene from across the Indian subcontinent
The Indian subcontinent is a physiographical region in Southern Asia. It is situated on the I ...
'', and a species of hippopotamus belonging to the genus ''
Hexaprotodon
''Hexaprotodon'' is an extinct genus of hippopotamid known from Asia. The name ''Hexaprotodon'' means "six front teeth" as some of the fossil forms have three pairs of incisors. ''. A late record of approximately 56,000 years
Before Present
Before Present (BP) years, or "years before present", is a time scale used mainly in archaeology, geology and other scientific disciplines to specify when events occurred relative to the origin of practical radiocarbon dating in the 1950s. Becaus ...
is known from the banks of the
Dhasan River
The Dhasan River is a river in central India. A right bank tributary of the Betwa River, it originates in Begumganj tehsil (Raisen district, Madhya Pradesh).
The river forms the southeastern boundary of the Lalitpur District of Uttar Pradesh ...
on the
Ganga plain in
Uttar Pradesh
Uttar Pradesh (; , 'Northern Province') is a state in northern India. With over 200 million inhabitants, it is the most populated state in India as well as the most populous country subdivision in the world. It was established in 1950 ...
. 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
''Palaeoloxodon naumanni'', occasionally called Naumann's elephant, is an extinct species belonging to the genus ''Palaeoloxodon'' found in the Japanese archipelago during the Middle to Late Pleistocene around 430,000 to 24,000 years ago. It is na ...
'' (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
Sulawesi (), also known as Celebes (), is an island in Indonesia. One of the four Greater Sunda Islands, and the world's eleventh-largest island, it is situated east of Borneo, west of the Maluku Islands, and south of Mindanao and the Sulu Ar ...
in Indonesia, similar in size to that reported for the Indian subcontinent.
Size
![Largest land mammals size chart](https://upload.wikimedia.org/wikipedia/commons/4/44/Largest_land_mammals_size_chart.jpg)
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
Titration (also known as titrimetry and volumetric analysis) is a common laboratory method of quantitative chemical analysis to determine the concentration of an identified analyte (a substance to be analyzed). A reagent, termed the ''titrant'' ...
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