Elephantidae

Elephantidae
Temporal range: Pliocene–Present
A male Asian elephant (Elephas maximus) in the wild at Bandipur National Park in India
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Proboscidea
Superfamily: Elephantoidea
Family: Elephantidae
Gray, 1821
Type species
Elephas maximus
Linnaeus, 1758

The Elephantidae are 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 Proboscidea. Elephantidae have 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
See also: List of elephant species and Elephants

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 has been frequently revised. Some relationships within the order remain unclear, and it is incompletely summarised as:[1]

The most accurate phylogenetic tree of the elephants and mammoths as of 2010
Elephantimorpha (Proboscidea)
Elephantida
Stegodontidae
†Stegolophodon
†Stegodon
Elephantidae (elephants and mammoths)
†Primelephas
Loxodonta
Elephas
†Mammuthus
†Palaeoloxodon
†Stegotetrabelodon
†Stegodibelodon
†Gomphotheriidae
†Mammutida
†Mammutidae (mastodons)
Mammut
Zygolophodon
incertae sedis
Eritreum

The genera †Anancus, †Tetralophodon, †Stegomastodon, †Paratetralophodon and †Cuvieronius are placed by some authors within Elephantidae, while others place them in 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)
E. maximus Asian elephant
E. m. maximus Sri Lankan elephant
E. m. borneensis Borneo elephant
E. m. indicus Indian elephant
E. m. sumatranus Sumatran elephant
Loxodonta (African)
L. africana African bush elephant
L. cyclotis African 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, both within this family and in 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 very certain, by comparing genes, scientists have 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 the common ancestor of all three modern families likely was some kind of amphibious hyracoid. One hypothesis is that these animals spent most of their time underwater, 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 six hours and 50 km (31 mi).

In the past, a much wider variety of genera and species were found, including the mammoths and stegodons.[6][7]

See also

References

  1. ↑ Classification of the Elephantidae Paleobiology Database Accessed: August 2009
  2. ↑ Shoshani, J. (2005). "Order Proboscidea". In Wilson, D. E.; Reeder, D. M. Mammal Species of the World (3rd ed.). Johns Hopkins University Press. ISBN 978-0-8018-8221-0. OCLC 62265494.
  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" (PDF), Respiratory Physiology & Neurobiology 138 (2-3): 325–333, doi:10.1016/S1569-9048(03)00199-X
  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.

External links