Elephantidae is a taxonomic family, collectively elephants and mammoths. These are terrestrial large mammals with a trunk and tusks. Most genera and species in the family are extinct. Only two genera, Loxodonta (African elephants) and Elephas (Asiatic elephants), are living.

The family was first described by John Edward Gray in 1821, and later assigned to taxonomic ranks within the order of Proboscidea. Elephantidae has also been revised by various authors to include or exclude other extinct proboscidean genera.

Classification

"Man, and the elephant" Plate from Hawkins A comparative view of the human and animal frame. 1860.

The family diverged from a common ancestor of the Mammutidae, which includes species termed as mastodons. The author of Mammutidae also published Gomphotheriidae, more closely related to Elephantidae, which also includes species previously described as Mastodon. The classification of proboscideans is unstable and frequently revised, some relationships within the order remain unclear, and it is incompletely summarised as:^[1]

Elephantimorpha (Proboscidea)

Elephantida

Elephantidae (elephants and mammoths)

†Primelephas

Loxodonta

Elephas

†Mammuthus

†Stegodon

†Stegolophodon

†Stegotetrabelodon

†Stegodibelodon

†Gomphotheriidae (Gomphothere)

†Mammutida

†Mammutidae (mastodons)

Mammut

Zygolophodon

incertae sedis

Eritreum

The genera †Anancus, †Tetralophodon, †Stegomastodon, †Paratetralophodon and †Cuvieronius are placed by some authors within the Elephantidae, while others give a treatment as Gomphotheriidae. Similarly, Stegodon and Stegolophodon have sometimes been placed in Stegodontidae. The systematics of the living subspecies and species, the modern elephants, has undergone several revisions. A list of extant Elephantidae, excluding the extinct species of the two genera, includes:^[2]

Elephantidae

Elephas (Asiatic)

Elephas maximus Asian Elephant

Elephas maximus maximus Sri Lankan Elephant

Elephas maximus borneensis Borneo Elephant

Elephas maximus indicus Indian Elephant

Elephas maximus sumatranus Sumatran Elephant

Loxodonta (African)

Loxodonta africana Bush Elephant

Loxodonta cyclotis Forest Elephant

Skeleton of Mammuthus meridionalis at MNHN

Scientific classification of Elephantidae taxa embraces an extensive record of fossil specimens, over millions of years, some of which existed until the end of the last ice age. Some species were extirpated more recently. The discovery of new specimens and proposed cladistics have resulted in systematic revisions of the family and related proboscideans.

Elephantidae are classified informally as the elephant family, or in a paleobiological context as elephants and mammoths. The common name elephant primarily refers to the living taxa, the modern elephants, but may also refer to a variety of extinct species, in this family and others (see Elephant (disambiguation)). Other members of Elaphantidae, especially members of Mammuthus, are referred to by the common name mammoth.

Evolutionary history

Evolution of elephants from the ancient Eocene (bottom) to the modern day (top).

Although the fossil evidence is uncertain, by comparing genes scientists discovered evidence that Elephantidae and other proboscideans share a distant ancestry with Sirenia (sea cows) and Hyracoidea (hyraxes).^[3] These have been assigned with the demostylians to the clade Paenungulata. In the distant past, members of the hyrax family grew to large sizes, and it seems likely that the common ancestor of all three modern families was some kind of amphibious hyracoid.^{[citation needed]} One hypothesis is that these animals spent most of their time under water, using their trunks like snorkels for breathing.^[4][5] Modern elephants have this ability and are known to swim in that manner for up to 6 hours and 50 km (31 mi).

In the past, there was a much wider variety of genera, including the mammoths and stegodons. There was also a much wider variety of species.^[6][7]

See also

• Elephant
• Embrithopoda

References

1. ^ Classification of the Elephantidae Paleobiology Database Accessed: August 2009
2. ^ Shoshani, Jeheskel (16 November 2005). "Order Proboscidea (pp. 90-91)". In Wilson, Don E., and Reeder, DeeAnn M., eds. Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Baltimore: Johns Hopkins University Press, 2 vols. (2142 pp.). ISBN 978-0-8018-8221-0. OCLC 62265494. http://www.bucknell.edu/msw3/browse.asp?id=11500002. 
3. ^ Ozawa, Tomowo; Seiji Hayashi, Victor M. Mikhelson (1997-04-24), "Phylogenetic Position of Mammoth and Steller's Sea Cow Within Tethytheria Demonstrated by Mitochondrial DNA Sequences", Journal of Molecular Evolution 44 (4): 406–413, doi:10.1007/PL00006160, PMID 9089080 
4. ^ West, John B. (2001), "Snorkel breathing in the elephant explains the unique anatomy of its pleura", Respiratory Physiology 126 (1): 1–8, doi:10.1016/S0034-5687(01)00203-1, PMID 11311306 
5. ^ West, John B.; Fu, Zhenxing; Gaeth, Ann P.; Short, Roger V. (2003-11-14), "Fetal lung development in the elephant reflects the adaptations required for snorkeling in adult life", Respiratory Physiology & Neurobiology 138 (2-3): 325–333, doi:10.1016/S1569-9048(03)00199-X, http://www.sciencedirect.com/science?_ob=MImg&_imagekey=B6X16-49MF0FR-2-7&_cdi=7234&_user=10&_orig=article&_coverDate=11%2F14%2F2003&_sk=998619997&view=c&wchp=dGLbVzb-zSkWA&md5=ad91a1eea54ef52d0a723aeec5232049&ie=/sdarticle.pdf 
6. ^ Todd, N. E. (2001). African Elephas recki: time, space and taxonomy (pdf). In: Cavarretta, G., P. Gioia, M. Mussi, and M. R. Palombo. The World of Elephants, Proceedings of the 1st International Congress. Consiglio Nazionale delle Ricerche. Rome, Italy.
7. ^ Todd, N. E. (2005). Reanalysis of African Elephas recki: implications for time, space and taxonomy. Quaternary International 126-128:65-72.