Vertebrate Zoology - V. M. Konstantinov 2011

Chordates
Terrestrial, or Tetrapod, Vertebrates — Vertebrates with Embryonic Membranes
Class Mammalia, or Mammals — Subclass Theria — Suborder Odontoceti (Toothed Whales) — Order Proboscidea

Proboscideans are a numerous, diverse, and widely distributed group of mammals during the Paleogene and Neogene periods, of which only two species survive today. They are the largest land mammals. Their primary distinguishing feature is the trunk, a highly elongated Nose fused with the upper lip. Only the Base of the trunk is supported by Cartilage; the rest of the Structure is purely musculocutaneous. Elephants use their trunks to smell, Touch, and grasp objects. Their limbs are five-toed with small hooves. The Skin is very thick and, in modern species, almost hairless. Their dentition is highly specialized. The upper incisors form tusks—sometimes enormous and protruding far from the Mouth—that grow continuously throughout life. Molars do not erupt all at once, but sequentially. There is only one functional molar on each side of the jaw at any given time. As a tooth wears down, it is replaced by a new one that develops behind the previous one and moves forward to take its place. Canines are absent.

Elephants live for about 70 to 80 years and reach sexual maturity between the ages of 10 and 16. Although elephants have been kept in captivity for millennia, successful breeding has only been established in a few select zoos. Notably, Asian elephants have successfully bred at the Moscow Zoo.

In the Asian elephant (Elephas maximus), only males possess tusks. Their ears are triangular and sweep backward. Body height is approximately 3 m. They inhabit the tropical forests of India, Sri Lanka, Sumatra, and Borneo. They are easily tamed, though they breed poorly in captivity.

The African elephant (Loxodonta africana) is distinguished by its larger size (shoulder height up to 3.5 m), large drooping ears, and the presence of tusks in both males and females. It is distributed across tropical Africa and is very difficult to tame. African elephants currently survive in greater numbers than Asian elephants.

The extinct woolly mammoth (Elephas primigenius) that once inhabited the tundras is closely related to the Asian elephant. Its tusks and remains of soft tissue are quite frequently discovered in the permafrost of northern Siberia. The Zoological Institute of the Russian Academy of Sciences in St. Petersburg exhibits exceptionally well-preserved taxidermy mounts of an adult mammoth and a calf recovered from the permafrost.