Tuesday, May 16, 2006

DISCUSSION OF IDENTIFYING CHARACTERISTICS OF EACH ORDER OF PLACENTAL MAMMALS, INCLUDING A LIST OF ANIMALS REPRESENTING EACH ORDER

There are six orders which are found on placental mammals; these include Chipoptera, Pholidata, Carnivora, Perissodactyla (odd-toed ungulates), Artiodactyla (even-toed ungulates) and Cetacea. These orders have some characteristics which identifies them from each other.Chiroptera have long slender fingers covered with by sheet leathery skin. The skins are connected to their sides, legs and tails to make a wing.
The example for Chiroptera is bats. Bats have modified forelimbs which support wing membrane. Bats have most elongated parts of the limb are those of hands (metacarpal bones) and fingers. Numerous blood vessels and nerves are present throughout the wing membrane. Bats have five unique muscles present in the patagium and use addition muscle which is found in the chest and back to move the wings up and down. The hind limbs are unique.The examples of Artiodactyla are cow, sheep, pig, giraffe and hippopotamus. This is the order of even toed hoofed animals has only two toes on which it stands. Standing on two toes provides better control than on a flat foot. Animals which run very fast in this order are those that run either on all their toes or on one toe. The giraffes have unique elastic vessels which provide the ability to raise and lower the head. This species have high shoulders and slopping back. The front legs are much longer than hind legs. The body of the giraffe is covered with brown patches.
The examples of carnivore are dogs, cats, lion, skunk, walrus, sea and sea lion. Animals of the order carnivore hunt meat, and usually have sharp claws and long cone like. Carnivores have canine teeth which are used for seizing and stabling their prey. Some teeth are sharp and they act like scissor blades. They have furry or hairy coat. The main feature of the head is squarish snout. Their eyes are small and ears are internal. They have special air sacs below to their throats that allow them bob vertically in the water while sleeping.
The examples of animals that belong to order Cetacea include whales, dolphins and porpoises. Cetacea have bodies that are adapted for water but they are still air- breathing mammals that sticks their nostrils on the water every once in a while or they will drown. Cetacea have torpedo-shaped bodies, forelimbs that have been modified flippers and tails that are flattened side to side to become flukes. The majority of cetacean has no sweat glands and their skins are smooth and virtually hairless. Toothed whales are usually small to medium sized. They have skulls that that are bilaterally asymmetrically and it supports a round called melon. They have a single blowhole and a fused lower jaw.
Scaly anteater is the example of Pholidota. Pholidata are covered with large, overlapping scales made up of agglutinated hair. They have extraordinary long and strong tongue. The tongue passes over sternum and anchored to long process of the pelvis. They have ability to close eyes, nostrils and eyes apparently. The scales, coupled with the ability to curl into tight ball.Perissodactyla are a small order of herbivores which is comprised of species such as horse, zebra and rhinoceros. They are distinguishing from other ungulates by their odd number of toes.
The species of order Perissodacyla contained some largest land mammals such as Indricotherium, a relative of the rhinoceros which stood more than five meters tall at the shoulder and weighed estimated fifteen to twenty tons. Rhinocerotidae have three toes per foot. At the skull is elongated by stretching of the facial bones rather than the braincase. The nasal bones in the skull are expanded posteriorly and the project is freely for at least part of their length. Horns are present on the midline of the nasal or frontal bones in all members of Rhinocerotidae. However, these are dermal of origin and have no bony core as in the artiodactyls.

Chiroptera have long slender fingers covered with by sheet leathery skin. Artiodactyla is the order of even toed hoofed animals has only two toes on which it stands. Animals of the order carnivore hunt meat, and usually have sharp claws and long cone like. Cetacea have bodies that are adapted for water. Pholidata are covered with large, overlapping scales made up of agglutinated hair. Perissodactyla are distinguishing from other ungulates by their odd number of toes.
Reference

Wikipedia Contributor. Placental mammals, The free Encyclopedia [internet] 2006 May 06, 08:30 UT C [cited 2006 May 08] Available from: http://en.wikipedia.org/wiki/placental

Masiya Kedibone
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