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''Palaeoloxodon'' is an extinct
genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
of
elephant Elephants are the largest existing land animals. Three living species are currently recognised: the African bush elephant, the African forest elephant, and the Asian elephant. They are the only surviving members of the family Elephantidae an ...
. The genus originated in Africa during the
Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...
era. The genus contains some of the largest known species of elephants, over four metres tall at the shoulders, including the European
straight-tusked elephant 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 ...
(''Palaeoloxodon antiquus''), and the southern Asian ''
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 r ...
'', the latter of which was possibly the largest known land mammal based on fragmentary remains, but this requires proper reexamination. In contrast, the genus also contains many species of dwarf elephants that evolved via
insular dwarfism Insular dwarfism, a form of phyletic dwarfism, is the process and condition of large animals evolving or having a reduced body size when their population's range is limited to a small environment, primarily islands. This natural process is disti ...
on islands in the Mediterranean, some only a metre in height, making them the smallest elephants known. The genus has a long and complex taxonomic history, and at various times, it has been considered to belong to '' Loxodonta'' or ''
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 ...
'', but today is usually considered a valid and separate genus in its own right.


Taxonomy

In 1924,
circumscribed In geometry, the circumscribed circle or circumcircle of a polygon is a circle that passes through all the vertices of the polygon. The center of this circle is called the circumcenter and its radius is called the circumradius. Not every polyg ...
''Palaeoloxodon'' as a subgenus of '' Loxodonta''. It included the "''E. antiquus—namadicus''
group A group is a number of persons or things that are located, gathered, or classed together. Groups of people * Cultural group, a group whose members share the same cultural identity * Ethnic group, a group whose members share the same ethnic ide ...
", and he designated "'' E. namadicus naumanni'' Mak." as its
type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...
. ''Palaeoloxodon'' was later thought to be a
subgenus In biology, a subgenus (plural: subgenera) is a taxonomic rank directly below genus. In the International Code of Zoological Nomenclature, a subgeneric name can be used independently or included in a species name, in parentheses, placed between t ...
of ''
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 ...
'', but this was abandoned by 2007. In 2016, a
mitochondrial DNA Mitochondrial DNA (mtDNA or mDNA) is the DNA located in mitochondria, cellular organelles within eukaryotic cells that convert chemical energy from food into a form that cells can use, such as adenosine triphosphate (ATP). Mitochondrial D ...
sequence analysis of ''P. antiquus'' found that it was nested within the genus '' Loxodonta'', more closely related
African forest elephant The African forest elephant (''Loxodonta cyclotis'') is one of the two living African elephant species. It is native to humid forests in West Africa and the Congo Basin. It is the smallest of the three living elephant species, reaching a should ...
, ''Loxodonta cyclotis,'' than the
African bush elephant The African bush elephant (''Loxodonta africana'') is one of two extant African elephant species and one of three extant elephant species. It is the largest living terrestrial animal, with bulls reaching a shoulder height of up to and a body ...
, ''Loxodonta africana.'' The authors suggested that this invalidated the genus ''Palaeoloxodon'' as currently recognized. A second study published in 2018 based on the
nuclear genome Nuclear DNA (nDNA), or nuclear deoxyribonucleic acid, is the DNA contained within each cell nucleus of a eukaryotic organism. It encodes for the majority of the genome in eukaryotes, with mitochondrial DNA and plastid DNA coding for the rest. I ...
suggested ''P. antiquus'' had a complex hybridization history, with over 60% of its DNA coming from a lineage closest to but outside the two extant '' Loxodonta'' species, around 6% from ''
Mammuthus A mammoth is any species of the extinct elephantid genus ''Mammuthus'', one of the many genera that make up the order of trunked mammals called proboscideans. The various species of mammoth were commonly equipped with long, curved tusks and, ...
'' and 30% from a lineage closer to ''L. cyclotis'' than ''L. africana''. The hybridisation probably took place in Africa, where ''Palaeoloxodon'' was dominant for most of the Pliocene and Early Pleistocene.


Mainland species

* '' P. recki'' (Synonym:''Elephas recki'') (East Africa), the oldest (4.0 - 0.6 million years ago) and one of the largest species *'' P. antiquus'' (Synonym:''Elephas antiquus'') (Straight tusked elephant) (Europe, Middle East, western Asia) * ?'' P. huaihoensis'' (China) possibly synonymous with ''P. naumanni'' * '' P. namadicus ''(Synonym:''Elephas namadicus'') (Indian subcontinent, possibly also elsewhere in Asia), the largest in its genus, and possibly the largest terrestrial mammal ever * ''
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 ...
''(Synonym:''E. namadicus naumanni'') (Japan, possibly also China and Korea), possible subspecies of ''E. namadicus'' * ?''P. turkmenicus'' known from a single specimen found in the Middle Pleistocene of Turkmenistan, with possibly attributable remains known from Kashmir, validity uncertain. *


Mediterranean island dwarfs

These Mediterranean insular
dwarf elephant Dwarf elephants are prehistoric members of the order Proboscidea which, through the process of allopatric speciation on islands, evolved much smaller body sizes (around ) in comparison with their immediate ancestors. Dwarf elephants are an example ...
species are almost certainly descended from ''P. antiquus'' *'' P. chaniensis'' (Crete) * '' P. creutzburgi'' (Crete) *'' P. xylophagou'' (Cyprus) * '' P. cypriotes'' (Cyprus) * '' P. lomolinoi'' (Naxos) * ''P. tiliensis'' (Tilos) * '' P. melitensis'' (Malta) * '' P. mnaidriensis'' (Sicily and Malta) *'' P. falconeri''/''E. falconeri''Benoit, J., Legendre, L. J., Tabuce, R., Obada, T., Mararescul, V., & Manger, P. (2019). Brain evolution in Proboscidea (Mammalia, Afrotheria) across the Cenozoic. ''Scientific Reports, 9''(1), 9323. https://doi.org/10.1038/s41598-019-45888-4 (Sicily and Malta)


Description

Most species of ''Palaeoloxodon'' (aside from ''P. turkmenicus'') are noted for their distinctive parieto-occipital crests present at the top of the cranium, which was used to anchor the
splenius 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 ...
as well as possibly the
rhomboid Traditionally, in two-dimensional geometry, a rhomboid is a parallelogram in which adjacent sides are of unequal lengths and angles are non-right angled. A parallelogram with sides of equal length (equilateral) is a rhombus but not a rhomboid. ...
muscles to support the skull, which is proportionally large in comparison to other elephants. The tusks have relatively little curvature, and are proportionally large.


Evolution

''Palaeoloxodon'' first appears in the fossil record in Africa during the early Pliocene, around 4 Mya as the species ''
Palaeoloxodon recki ''Palaeoloxodon recki'' is an extinct species of elephant native to Africa during the Pliocene and Pleistocene. At up to 14 feet (4.27 metres) in shoulder height, it was one of the largest elephant species to have ever lived. It is believed that ...
.'' ''P. recki'' was the dominant elephant in Africa for the Pliocene and most of the Pleistocene. A population of ''P. recki'' migrated out of Africa between 0.8 and 0.6 Mya, diversifying into the radiation of Eurasian ''Palaeoloxodon'' species, including ''P. antiquus, P. namadicus'', and ''P. naumanni'', the precise relationships of the Eurasian taxa to each other are obscure in the absence of molecular evidence. ''P. recki'' became extinct in Africa around 0.5 Mya, being replaced by the modern genus ''Loxodonta''. A species descended from ''P. recki'', "''Elephas''" ''jolensis'' persisted in Africa until the late Middle Pleistocene, around 130,000 years ago. The arrival of ''P. antiquus'' in Europe co-incides with the extinction ''of
Mammuthus meridionalis ''Mammuthus meridionalis'', or the southern mammoth, is an extinct species of mammoth native to Europe and Central Asia from the Gelasian stage of the Early Pleistocene, living from 2.5–0.8 mya. Taxonomy The taxonomy of extinct elephant ...
'' and its replacement by ''
Mammuthus trogontherii The steppe mammoth (''Mammuthus trogontherii'', sometimes ''Mammuthus armeniacus'') is an extinct species of Elephantidae that ranged over most of northern Eurasia during the late Early and Middle Pleistocene, approximately 1.8 million-200,000 y ...
,'' suggesting that it might have shared a similar dietary niche and outcompeted the former. ''P. antiquus'' was able to disperse onto many islands in the
Mediterranean The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on the e ...
, undergoing insular dwarfism and speciating into numerous distinct varieties of
dwarf elephant Dwarf elephants are prehistoric members of the order Proboscidea which, through the process of allopatric speciation on islands, evolved much smaller body sizes (around ) in comparison with their immediate ancestors. Dwarf elephants are an example ...
s. ''Palaeoloxodon'' fossils are abundant in China and are assigned to three species, ''P. namadicus, P. naumanni'' and ''P. huaihoensis.'' However, the relationships of Chinese ''Palaeoloxodon'' are currently unresolved and it is unclear how many species were present in the region.


Extinction

Most Eurasian species of ''Palaeoloxodon'' became extinct towards the end of the last glacial period. The youngest record of ''P. antiquus'' are footprints from the southern Iberian Peninsula, dating to approximately 28,000 years ago. The youngest Japanese records of ''P. naumanni'' date to around 24,000 years ago. Similar dates have been reported for Indian ''P. namadicus'' and Chinese ''Palaeoloxodon''. Some of the Mediterranean dwarf species held on for longer, with the youngest dates for the Cyprus dwarf elephant around 12,000 years ago. ''P. tiliensis'' from the Greek island of
Tilos Tílos ( el, Τήλος; grc, Τῆλος, Telos) is a small Greek island and municipality located in the Aegean Sea. It is part of the Dodecanese group of islands, and lies midway between Kos and Rhodes. It has a population of 780 inhabitants ( ...
was suggested to have survived as recently as 3,500 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 ...
based on preliminary radiocarbon dating done in the 1970s, which would make it the youngest surviving elephant in Europe, but this has not been thoroughly investigated. In a 2012 paper, Li Ji and colleagues from the Institute of Geographic Sciences and Natural Resources Research,
Beijing } Beijing ( ; ; ), alternatively romanized as Peking ( ), is the capital of the People's Republic of China. It is the center of power and development of the country. Beijing is the world's most populous national capital city, with over 21 ...
, argued that 3000 year old teeth from Northern China previously believed to belong to Asian elephants were actually those of ''Palaeoloxodon''. They also argued that Chinese ritual bronze vessels depicting trunks with two "fingers" must be ''Palaeoloxodon'' (which are only known from bones; their trunk characteristics are unknown) because Asian elephants only have one. Fossil elephant experts
Victoria Herridge Victoria Louise "Tori" Herridge, born 1980, is a palaeontologist at the Natural History Museum in London and one of the founders of TrowelBlazers, which celebrates women archaeologists, palaeontologists and geologists. Career Herridge gradua ...
and Adrian Lister disagree with the assignment, stating that the claimed diagnostic dental features are actually contrast artifacts created due to the low
image resolution Image resolution is the detail an image holds. The term applies to digital images, film images, and other types of images. "Higher resolution" means more image detail. Image resolution can be measured in various ways. Resolution quantifies how ...
of the figures in the
scientific paper : ''For a broader class of literature, see Academic publishing.'' Scientific literature comprises scholarly publications that report original empirical and theoretical work in the natural and social sciences. Within an academic field, scienti ...
, which are not evident in better-quality
photograph A photograph (also known as a photo, image, or picture) is an image created by light falling on a photosensitive surface, usually photographic film or an electronic image sensor, such as a CCD or a CMOS chip. Most photographs are now create ...
s, and that the Bronze age vessels could be the result of stylistic choice.


References

{{Taxonbar, from=Q1523445 Prehistoric elephants Pliocene proboscideans Pleistocene proboscideans Prehistoric placental genera