Elephantidae is a

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

of large, herbivorous proboscidean mammals which includes the living

elephants Elephants are the Largest and heaviest animals, largest living land animals. Three living species are currently recognised: the African bush elephant (''Loxodonta africana''), the African forest elephant (''L. cyclotis''), and the Asian ele ...

(belonging to the genera ''

Elephas ''Elephas'' is a genus of elephants and one of two surviving genera in the Family (biology), family Elephantidae, comprising one extant species, the Asian elephant (''E. maximus''). Several extinct species have been identified as belonging to t ...

'' and '' Loxodonta''), as well as a number of extinct genera like '' Mammuthus'' (mammoths) and ''

Palaeoloxodon ''Palaeoloxodon'' is an extinct genus of elephant. The genus originated in Africa during the Early Pleistocene, and expanded into Eurasia at the beginning of the Middle Pleistocene. The genus contains the largest known species of elephants, with ...

''. They are large terrestrial

mammal A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three ...

s with a

snout A snout is the protruding portion of an animal's face, consisting of its nose, mouth, and jaw. In many animals, the structure is called a muzzle, Rostrum (anatomy), rostrum, beak or proboscis. The wet furless surface around the nostrils of the n ...

modified into a trunk and

teeth A tooth (: teeth) is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, tear ...

modified into

tusk Tusks are elongated, continuously growing front teeth that protrude well beyond the mouth of certain mammal species. They are most commonly canine tooth, canine teeth, as with Narwhal, narwhals, chevrotains, musk deer, water deer, muntjac, pigs, ...

s. Most

genera Genus (; : genera ) is a taxonomic rank above species and below family as used in the biological classification of living and fossil organisms as well as viruses. In binomial nomenclature, the genus name forms the first part of the binomial s ...

and

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

in the family are

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

. The family was first described by

John Edward Gray John Edward Gray (12 February 1800 – 7 March 1875) was a British zoologist. He was the elder brother of zoologist George Robert Gray and son of the pharmacologist and botanist Samuel Frederick Gray (1766–1828). The same is used for a z ...

in 1821, and later assigned to taxonomic ranks within the order Proboscidea. Elephantidae has been revised by various authors to include or exclude other extinct proboscidean genera.

Description

Elephantids are distinguished from more basal proboscideans like

gomphotheres Gomphotheres are an extinct group of proboscideans related to modern Elephant, elephants. First appearing in Africa during the Oligocene, they dispersed into Eurasia and North America during the Miocene and arrived in South America during the Ple ...

by their teeth, which have parallel lophs, formed from the merger of the cusps found in the teeth of more basal proboscideans, which are bound by

cementum Cementum is a specialized calcified substance covering the root of a tooth. The cementum is the part of the periodontium that attaches the teeth to the alveolar bone by anchoring the periodontal ligament. Structure The cells of cementum are ...

. In later elephantids, these lophs became narrow lamellae/plates, which are pockets of enamel filled with dentine, which are arranged successively like a concertina.V.L. Herridg
Dwarf Elephants on Mediterranean Islands: A Natural Experiment in Parallel Evolution. PhD Thesis, Vol 1.
p. 32 University College London (2010) The number of lophs/lamellae per tooth, as well as the tooth crown height ( hypsodonty) is greater in later species. Elephantids chew using a proal jaw movement involving a forward stroke of the lower jaws, different from the oblique movement using side to side motion of the jaws in more primitive proboscideans. The most primitive elephantid ''

Stegotetrabelodon ''Stegotetrabelodon'' ("four roofed tusked-tooth") is an extinct genus of primitive elephantid from the Late Miocene to Early Pliocene of Africa, the Arabian Peninsula, and Italy. It is the earliest and most primitive member of the family, notab ...

'' had a long lower jaw with lower tusks and retained permanent premolars similar to many gomphotheres, while modern elephantids lack permanent premolars, with the lower jaw being shortened (brevirostrine) and lower tusks being absent. Elephantids are typically

sexually dimorphic Sexual dimorphism is the condition where sexes of the same species exhibit different Morphology (biology), morphological characteristics, including characteristics not directly involved in reproduction. The condition occurs in most dioecy, di ...

, with substantially larger males, with an accelerated growth rate over a longer period of time than females. Elephantidae contains some of the largest known proboscideans, with fully-grown males of some species of

mammoths A mammoth is any species of the extinct elephantid genus ''Mammuthus.'' They lived from the late Miocene epoch (from around 6.2 million years ago) into the Holocene until about 4,000 years ago, with mammoth species at various times inhabi ...

and ''

'' having average body masses of and respectively, making them among the largest terrestrial mammals ever. One species of ''Palaeoloxodon'', '' Palaeoloxodon namadicus'', has been suggested to have been possibly the largest land mammal of all time, though this remains speculative due to the fragmentary nature of known remains. In comparison to more basal elephantimorphs like gomphotheres, the bodies of elephantids tend to be proportionally shorter from front to back, as well having more elongate limbs with more slender limb bones.

Ecology

Living female and juvenile elephants live in

matriarchal Matriarchy is a social system in which positions of power and privilege are held by women. In a broader sense it can also extend to moral authority, social privilege, and control of property. While those definitions apply in general English, ...

(female-led) herds of related individuals, with males leaving these groups to live solitarily upon reaching adolescence around 14–15 years of age. Evidence has been found that extinct elephantids, including the most primitive elephantid, ''

'', also lived in herds based on footprint tracks.

Classification

Some authors have suggested to classify the family into two subfamilies, Stegotetrabelodontinae, which is monotypic, only containing ''Stegotetrabelodon'', and Elephantinae, containing all other elephantids. Recent genetic research has indicated that ''

'' and '' Mammuthus'' are more closely related to each other than to '' Loxodonta'', with ''

'' closely related to ''Loxodonta''. ''Palaeoloxodon'' also appears to have received extensive hybridisation with the

African forest elephant The African forest elephant (''Loxodonta cyclotis'') is one of the two living species of African elephant, along with the African bush elephant. It is native to humid tropical forests in West Africa and the Congo Basin. It is the smallest of the ...

, and to a lesser extent with mammoths.

Living species

*'' Loxodonta'' (African) **''L. africana''

African bush elephant The African bush elephant (''Loxodonta africana''), also known as the African savanna elephant, is a species of elephant native to sub-Saharan Africa. It is one of three extant elephant species and, along with the African forest elephant, one ...

**''L. cyclotis''

*''

'' (Asiatic) **''E. maximus''

Asian elephant The Asian elephant (''Elephas maximus''), also known as the Asiatic elephant, is the only living ''Elephas'' species. It is the largest living land animal in Asia and the second largest living Elephantidae, elephantid in the world. It is char ...

***''E. m. maximus'' Sri Lankan elephant ***''E. m. indicus''

Indian elephant The Indian elephant (''Elephas maximus indicus'') is one of three extant recognized subspecies of the Asian elephant, native to mainland Asia. The species is smaller than the African elephant species with a convex back and the highest body po ...

***''E. m. sumatranus'' Sumatran elephant ***''E. m. borneensis'' Borneo elephant

Classification

*Elephantidae **†''

'' (4 species) **Subfamily Elephantinae ***†'' Primelephas'' (2 species) ***''

'' (7+ species) ***†'' Stegoloxodon'' (2 species) ***'' Loxodonta'' (6 species) ***†''

'' (14+ species) ***†'' Phanagoroloxodon'' (1 species) ***†'' Mammuthus'' (10 species) ***†''

Stegodibelodon ''Stegodibelodon'' is an extinct genus of primitive Elephantidae, elephantid known from the Early Pliocene of Africa. It is known only from the Bodélé Depression, Djourab region of northern Chad, where it was discovered in 1964 by the hydrogeol ...

'' (1 species) ***†'' Selenetherium'' (1 species)

Evolutionary history

During the Late Miocene, around 10-8 million years ago, the earliest members of the family Elephantidae emerged in Afro-Arabia, having originated from gomphotheres, most likely from members of the genus '' Tetralophodon''. The earliest members of the modern genera of Elephantidae appeared during the latest Miocene–early Pliocene around 6-5 million years ago. The elephantid genera ''Elephas'' (which includes the living Asian elephant) and ''Mammuthus'' (mammoths) migrated out of Africa during the late Pliocene, around 3.6 to 3.2 million years ago. Mammoths then migrated into North America around 1.5 million years ago. At the end of the Early Pleistocene, around 800,000 years ago the elephantid genus ''

'' dispersed outside of Africa, becoming widely distributed in Eurasia. ''

'' became extinct as part of the

Late Pleistocene extinctions The Late Pleistocene to the beginning of the Holocene saw the extinction of the majority of the world's megafauna, typically defined as animal species having body masses over , which resulted in a collapse in faunal density and diversity acro ...

, with mammoths only surviving in relict populations on islands around the

Bering Strait The Bering Strait ( , ; ) is a strait between the Pacific and Arctic oceans, separating the Chukchi Peninsula of the Russian Far East from the Seward Peninsula of Alaska. The present Russia–United States maritime boundary is at 168° 58' ...

into the Holocene, with their latest survival being on

Wrangel Island Wrangel Island (, ; , , ) is an island of the Chukotka Autonomous Okrug, Russia. It is the List of islands by area, 92nd-largest island in the world and roughly the size of Crete. Located in the Arctic Ocean between the Chukchi Sea and East Si ...

, where they persisted until around 4,000 years ago.

References

External links

* * {{Proboscidea Genera Extant Pliocene first appearances Mammal families Proboscideans Taxa named by John Edward Gray Elephants

Description

Ecology

Classification

Living species

Classification

Evolutionary history

See also

References

External links