Taxonomy
Order
African and Asian elephants are the only surviving members of the Order Proboscidea.
Species
Historically, elephants were classified into two species, the African (Loxodonta africana) and Asian (Elephas maximus) elephants. However, genetic research has provided new insight to elephant "relatedness" and taxonomic classification at the subspecies level.
African elephant classification is ongoing research. Preliminary genetic studies have indicated there are at least two subspecies of African elephants, namely the savanna (Loxodonta africana africana) and forest (Loxodonta africana cyclotis) elephants. However, elephant taxonomy may further diversify in the future, as genetic and phylogenic research indicates additional subspecies. Forest and savanna elephants are differentiated by geographic distribution and several physical characteristics.
- African elephants inhabit the sub-Saharan regions of Africa. The savanna elephant (Loxodonta africana africana) resides on the savanna and grassy plains of east and South Africa. Forest elephants (Loxodonta africana cyclotis) inhabit forested regions of central and western Africa.
- The savanna elephant is larger than the forest subspecies. In fact, it is the largest land animal in the world. Refer to the Physical Characteristics section for in-depth differentiation between the two subspecies.
There are four recognized subspecies of Asian elephants, the Sri Lankan subspecies (Elephas maximus maximus) the mainland subspecies (Elephas maximus indicus), the Borneo subspecies (Elephas maximus borneensis), and the Sumatran subspecies (Elephas maximus sumatranus). However, elephant taxonomy may further diversify in the future, as genetic and phylogenic research indicates additional subspecies. The three subspecies are differentiated by geographic distribution and several physical characteristics.
- Asian elephants inhabit the southern, eastern and southeastern parts of Asia. The Indian elephant (E.m. indicus) has the broadest distribution, extending between the southern and southeastern regions of Asia. Sumatran (E.m. sumatrensis) and Sri Lankan (E.m. maximus) elephants inhabit Sumatra and the southwestern portions of Sri Lanka respectively. Borneo elephants inhabit Sabah, Malaysia, and Kalimantan regions of Borneo.
- The Sri Lankan elephant is the largest of all three Asian elephant subspecies. Refer to the Physical Characteristics section for in-depth differentiation between the three subspecies.
- The Borneo elephant subspecies was identified in 2003 based on mitochondrial DNA research that distinguished them genetically from other Asian subspecies. They are the smallest in size and have the longest tail length of all four species, often touching the ground.
Nomenclature
The Order Proboscidea derived its name from the Latin word "proboscis" meaning trunk.
The word elephant is derived from the Greek word "elephas" that means ivory.
Fossil Record
Elephants are the only living members of the Order Proboscidea today. However, modern day elephants represent only one of many proboscid families that have existed throughout history. Elephant ancestry spans over 55 million years and includes more than 300 proboscidean species. Proboscideans have ranged throughout the world, except Australia, Antarctica, and a few islands. These large animals inhabited numerous habitats, from aquatic to tundra. The Order Proboscidea has one of the most comprehensive fossil records of any species.
Moeritherium
The earliest member of the Order Proboscidea was Moeritherium. Its name was derived from the ancient Lake Moeris (modern name- Lake Qarun) in the Fayum Basin in Egypt.
Moeritheriums lived during the Eocene epoch about 50 to 55 million years ago. These small, pig-sized dinosaurs had long bodies and stout legs. Moeritheriums stood about one m (39 in.) in height. Although the animals did not possess trunks, the structure of the skull indicates they had an elongated snout, similar to a tapir’s, and thick upper lip. Moeritheriums were semi-aquatic herbivores, spending most of their life in and around water, consuming aquatic vegetation. The species ranged throughout North Africa.
Palaeomastodon
Palaeomastodons inhabited the Fayum Basin of Africa during the Oligocene epoch about 35 million years ago, living in forested and savanna habitats.
Palaeomastodons were about two m (6.6 ft.) in height and had a less developed trunk-like structure than modern elephants.
Barytherium
Barytheriums lived toward the middle/late Eocene epoch about 40 to 45 million years ago. There appears to have been two Barytherium species. The Barytherium grave species was about the size of the modern Asian elephant and the other unnamed species were about the size of a cow. These were semi-aquatic herbivores, spending much time in and around water consuming aquatic vegetation. Barytheriums inhabited North Africa.
Phiomia
Phiomia appeared in the fossil record during the Oligocene epoch, about 35 million years ago. They had two downward-curved tusks in their upper jaw and two straight tusks in their lower jaw. The tusks on the lower jaw facilitated feeding, while two downward-curved tusks in the upper jaw were used for defense. Phiomia was smaller in size than modern elephants, standing about 2.4 m (8ft.) tall at the shoulder. It was thought to have a short trunk-like structure based on the retracted position of the nasal bones. Phiomia were semi-aquatic herbivores, spending much time in and around water consuming aquatic vegetation, inhabiting areas around the El Fayum oasis in Egypt.
Phiomia cranium fossils indicate several elephantine features such as comparable size and air-filled compartments called diploe. The presence of diploe reduces the weight of the large skull.
Deinotherium
Deinotheriums lived in the Miocene epoch, about 25 million years ago. There are three known Genera of deinotheriums, Chilgatherium, Prodeinotherium, and Deinotherium. The largest species of deinotheriums was Deinotherium giganteum. This species was larger than the modern day elephant, standing about four m (13.1 ft.) in height at the shoulder. Deinotheriums possessed a trunk and downward-curved lower jaw and tusks. It is thought these tusks facilitated root digging and functioned as an anchor during rest periods in its semi-aquatic habitat. Deinotheriums ranged throughout Africa, Europe and southeast Asia.
Upon examining fossil remains, naturalists of the early 19th century thought deinotheriums were carnivorous sea monsters due to the formidable appearance of their downward-curved tusks. The name deinotherium was derived from the Greek word "deinos" meaning "terrible" and "therion" meaning "beast".
Gomphotheriidae
The Family Gomphotheriidae was a diverse group of proboscideans that included the following four Genera: Anacus, Cuvieronius, Gomphotherium and Platybelodon. The earliest gomphotheres lived during the Miocene epoch, about 20 million years ago.
Gomphotheres stood about three m (10 ft.) tall at the shoulder, had a trunk (varying in size, depending on the species), and two long slightly curved tusks in the upper jaw.
Gomphothere fossils have been found in Africa, Europe, Asia, and America.
- Anancus
- There were between four and 13 species in the Genus Anancus. This Genus had short jaws and lacked lower tusks. These large animals had pronounced upper tusks that perpetuated in length over time. Some Anancus species’ upper jaws and tusks reached such proportions that the length almost equaled that of the body.
- The species Anancus arvernensis lived during the Pliocene epoch about 10 million years ago. Anancus inhabited the open or wooded savannas in Europe. This species had extremely long upper tusks that reached three m (10 ft.) in length.
- The Anancus Genus possessed longer trunks than gomphotheres that lived in marshy and swampy habitats. Long trunks were possibly an adaptation for reaching high foliage.
- Cuvieronius
- Cuvieronius initially inhabited North America but was one of the few proboscideans that reached and colonized South America.
- This Genus had short jaws and lacked lower tusks. The upper tusks were over one m (39 in.) in length and were either rounded, straight, or upturned.
- Cuvieronius cranium fossils indicate several elephantine features such as comparable size and air-filled compartments called diploe. The presence of diploe reduces the weight of the large skull.
- Cuvieronius inhabited plains regions, feeding on a variety of plants and grasses in open or wooded savanna habitats.
- The Cuvieronius Genus possessed longer trunks than gomphotheres that lived in marshy and swampy habitats. Long trunks were possibly an adaptation for reaching high foliage.
- Platybelodon
- Genus Platybelodon inhabited the marshy and swampy habitats of Asia during the Miocene epoch, about 20 million years ago. These large animals had long jaws and broad lower tusks that formed huge shovels. Due to their tusks’ broad, scooped appearance, Platybelondons are often referred to as “shovel tuskers.” Tusks were used for uprooting plants in shallow waters.
- Gomphotherium
- The Gomphotherium Genus had widespread distribution throughout Africa, Asia, Europe, and North America during the Miocene epoch, about 20 million years ago. These large animals inhabited marsh and swamp habitats.
- Gomphotheriums were about the size of an Asian elephant and had upper and lower tusks. The lower tusks were large and shovel-like in appearance. Tusks were used for uprooting soft vegetation in shallow water. It is believed that gomphotheriums had short, well-developed trunks based on fossil evidence such as short necks, long limbs, and external nasal openings.
Mammut
The American mastodon (Mammut americanum) belongs to the Mammut Genus. Mastodons inhabited Africa, Europe and Asia during the Oligocene epoch about 25 million years ago. Mastodons migrated to North America, around seven million years ago, and then to South America, following the formation of the Central American land bridge.
Many complete mastodon skeletons have been discovered from Pleistocene swamps. Mastodons were about the size of modern Asian elephants, with two massive, slightly downward-curved tusks in the upper jaw. Tusks reached up to three m (10 ft.) in length and 25 cm (10 in.) in diameter. Presumably, only male mastodons had very short, straight tusks in the lower jaw.
The common name “mastodon” is derived from the Greek language meaning “breast-shaped tooth,” which refers to the shape of their cheek teeth.
Mastodons had long black-auburn hair on their body and possibly an underfur (shorter dense fur underneath the primary hair) to help keep warm in colder climates.
Fossil evidence suggests that mastodons inhabited forests and consumed various vegetation such as twigs and tree leaves.
Radiocarbon dating has identified the coexistence of mastodons and early man, around 10,000 to 12,000 years ago.
Stegodon
The Stegodontidae Family had a wide distribution throughout Asia during the Miocene and early Pliocene epochs, about four to eight million years ago. Stegodonts inhabited regions in Africa, Europe and even as far as Japan. Access to Japan was possible due to the massive lowering of sea levels during the Pleistocene glacial periods (650,000 to 10,000 years ago).
One of the best-known stegodonts was Stegodon ganesa. The Genus name, Stegodon, was derived from the Greek language "steg", which means "roof" and "odon" which means "tooth." This is a reference to Stegodonganesa's arched-shaped cheek teeth. The species name, ganesa, is a reference to the Hindu god of success that had an elephant-head.
Stegodons were about 3.5 m (11.5 ft.) in height and had massive upper tusks. The tusks of stegodons were extremely long and curved sideways and upwards. Analysis of stegodon skull anatomy revealed that the bones helping support the massive tusks were so close together that the trunk probably could not have been held between the two. It is possible the trunk rested on the tusks, a behavior seen in modern elephants as well.
Stegodons inhabited forested areas, staying close to water sources, and consuming a variety of vegetation such as bamboo and leaves.
Elephantidae
At one time, the Elephantidae family has comprised six genera (four of which are discussed below) and 26 species. Analysis of skull anatomy, reveals all members of the Elephantidae family had well-developed trunks based on the elevated position of the nostrils.
The Elephantidae family includes the two genera of modern elephants (Loxodonta and Elephas).
- Primelephas
- Primelephas inhabited the open, wooded savannas of East Africa during the Miocene epoch, around 20 million years ago. Primelephas had two pronounced tusks in the upper jaw, which became stronger and increased in length over time. The small, lower tusks gradually shortened over time and eventually disappeared.
- Primelephas is presumed to have given rise to other elephant species, including the modern Asian and African elephants and the mammoth.
- Mammuthus
- The familiar, woolly mammoth (Mammuthus primigenius) belongs to the Mammuthus Genus.
- Mammoths originated in warm forested areas of Africa during the Pliocene epoch, around three million years ago. These large animals migrated to Europe, Asia and North America about 120,000 years ago. Mammoths lived until the end of the Ice Age, about 10,000 years ago.
- Mammoths were slightly larger in size than modern Asian elephants, measuring over 39 m (13 ft.) at the shoulder and having longer, heavier tusks that curved upwards. Mammoth fur became increasingly thick and dense an adaptation for inhabiting cold North American climates.
- Mammoth illustrations and carvings, found on walls and ceilings of caves, support its coexistence with early man.
- Most of our early proboscidean knowledge of internal and external anatomy comes from well preserved fossilized remains. A nearly complete fossilized mammoth, nicknamed “Dima,” was discovered in the Soviet Union in 1977. It is estimated to be about 40,000 years old. The tissues are so well preserved, that scientists identified intact red blood cells and ancient proteins.
- Poxodonta & Elephas
- The African elephant (Loxodonta africana) originated in Africa, about 1.5 million years ago. Today, the African elephant is the largest living land animal.
- The Asian elephant (Elephas maximus) originated in Africa and migrated to Asia, where the species resides today.
Mammoths & Mastodons
Possibly the two most recognized elephant ancestors are the mammoths and the mastodons. Despite similarities such as geographic range (both species, at one time, inhabited North America) and similar appearances, there are several key differences.
Mammoths are more closely related to modern day elephants and are classified in the Elephantidae family along with them.
Mammoths were more prevalent in the western portion of North America, whereas the mastodon was more prevalent in the eastern portion.
Mastodons had a heavier, more bulky skeletal frame than the mammoth.
Mammoths had high-domed skulls (flattened on the front and back of their heads), whereas mastodons had low-domed skulls (flattened on the top and bottom of their heads).
Mammoths were mostly grazers, consuming a wide variety of grasses, whereas mastodons were mainly browsers, consuming a wide variety of plant material such as twigs and leaves.
Mammoths (Mammuthus) and mastodons (Mammut) genera names were derived from the Tartar word "mamut," which was a giant prehistoric rat.
Based on mitochondrial DNA studies, mammoths are more closely related to Asian elephants than either are related to African elephants.
Nearest Living Relatives to Elephants: Manatees & Hyraxes
Other elephant relatives that are still living today have been identified in the same geological strata (layer of earth, consistent with a specific time period) as Moeritherium. These living relatives to elephants are manatees and more distantly, hyraxes.
The elephant Order Proboscidea, the manatee Order Sirenia, and the hyrax Order Hyracoidea, have the following similar characteristics that provide further evidence to an ancestral relationship.
- Possess two mammary glands
- Similar heart structure-Refer to heart section under physical characteristics.
- Similar arrangement of teeth
Manatees
Manatees belong to the Order Sirenia. These aquatic animals can reach up to three m (10 ft.) in length and weigh between 363 to 544 kg (800-1200 lb.).
In both manatees and elephants, molars shift forward (towards the front of the mouth), gradually breaking off, and are replaced by those from behind. Additionally, manatees possess two incisors that structurally resemble elephant tusks.
Similar to female marine mammals, female elephants' reproductive anatomy is located on the lower belly.
Elephants and manatees have an atypical shaped heart that is circular. Refer to Physical characteristics - heart.
Hyraxes
Hyraxes are small African animals that are about 44 to 54 cm (18-22 in.) in length and weigh between 1.8 to 5.4 kg (4-12 lb.).
Hyraxes are more distantly related to elephants than manatees but share several anatomical similarities.
Elephants and hyraxes both possess thick, padded soles on the feet, which are used to cushion walking.
Hyraxes have four claws (toenails on the elephant) on its front feet and three on the rear (like the African elephant).
Hyraxes possess two incisors in its upper jaw that structurally resemble elephant tusks.
Historical Perspectives of Human-Elephant Relationships
Throughout history, elephants' size, strength, and agility have been utilized by humans in various capacities.
Adult male elephants have been used in military combat by many armies, such as the Persian Empire, Indian subcontinent armies, and Alexander the Great's troops.
Elephants are capable of carrying loads up to 500 kg (1,100 lb.) in weight. This great strength has enabled humans to transport heavy loads into mountainous terrain that is inaccessible to motorized vehicles. The logging industry has also benefited from working elephants' strength. Prior to mechanized transport, elephants carried massive tree loads, weighing more than four tons (around 9,000 lb.), to nearby rivers; where the load was then carried to respective sea ports. Today, timberjacks, bulldozers, and four wheel-drive vehicles have greatly reduced the need for elephant employment.
Field owners have used elephants to assist with strenuous agricultural tasks, such as plowing and drawing water carts.
The tourist industry has utilized elephants to enhance visitors' overall experience. Tourists get an elevated seat on the back an elephant to experience wildlife deep within jungles and savannas.
Elephants are revered in many cultures. Ceremonial-clad elephants frequently participate in ceremonies, festival, and cultural rituals.
