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CLASSIFICATION OF MAMMALS: THERIA

CLASSIFICATION OF MAMMALS: THERIA

  • 02 Jul 2017
THERIA
 
This group includes Mammals which show true mammals characters

Infraclass Metatheria:
 
They show almost all the Mammalian characters.
 
  1. Females show brood pouch or Marsupium on their ventral abdomen.
  2. Sebaceous glands are modified into mammary glands.
  3. Pelvic girdle shows epipubic bones. This supports Marsupium.
  4. Ribs are two headed.
  5. Carpus callosum is absent.
  6. Vagina and uterus are double (didefphic condition)
  7. They give birth to immature young ones.
  8. This infra class includes 1 order.
 
Order Marsupialia:
 
Ex: a) Didelphis – Opossum, b) Dasyurus - Tiger cat, c) Paramales - Bandicoot, d) Macropus - Kangaroo, e) Notorgetes - Marsupial mole
 
Infraclass Eutheria:
 
  1. Mammary glands are well developed.
  2. Double headed ribs are seen.
  3. Carpus callosum is present.
  4. Urinogenital organs will open independently into the Rectum.
  5. Testis are extra abdominal.
  6. Uterus and vagina are single.
  7. They show placenta in the development of embryo. This infra class is divided into following orders.
 
1. Order: Insectivora:
 
  1. Small animals are seen in this order.
  2. Snout is long.
  3. Five toed feet are seen.
  4. They are Nocturnal and Terrestrial
 
Ex: 1) Paraechinus (Hedgehog), 2) Talpa (mole), 3) Echinosorex (Shrews)
 
2. Order: Dermopetera:
 
  1. In between fore limbs and hind limbs, in between head and fore limb, in between hind limbs and tail, membrane is formed. This helps for gliding in air.
  2. They are Nocturnal.
 
Ex: Galeopithecus (Flying lemur)
 
3. Order: Chiroptera:
 
  1. Fore limbs are modified wings.
  2. Hind limbs are weak.
  3. Digits are clawed.
  4. Eyes are small and vision is very weak.
  5. They are usually called Bats.
 
Ex: Pteropus (Flying fox), Megaderma (Vampire bat)
 
4. Order: Primates:
 
  1. Hands and feet are more or less prehensile.
  2. Thumb is oppossable to other digits.
  3. Only two pectoral mammary glands are present.
  4. Cerebrum is big and convoluted.
 
Ex: 1) Chyromys (Aye aye), 2) Loris, 3) Hylobates (Gibbon), 4) Anthropithecus (Chimpanzee), 5) Simia satyrus (Orangutan), 6) Macaca (Monkey), 7) Homo Sapiens (man)
 
5. Order: Edentata:
 
  1. Feet has 5 digits. They are clawed.
  2. Testis are abdominal.
 
Ex: 1) Dasypus = ormadilla, 2) Bradypus = Three toed sloth, 3) Myrmecophaga' = Giant ant eater
 
6. Order: Pholidota:
 
  1. The body is covered by scales.
  2. In between scales hairs are present.
  3. Teeth are completely absent.
  4. Tongue is long, sticky and protrusible (Helpful to catch the ants).
 
Ex: 1) Manis (scaly ant eater or parigolin)
 
7. Order: Lagomorpha:
 
  1. Small mammals
  2. Tail is short.
 
Ex: Oryctologus - Rabbit, Lepus (Hare)
 
8. Order: Rodentia:
 
  1. Small mammals.
  2. Canines are absent. (Diastema is present)
 
Ex: Ratus ratus - Rat, Funambulus - Squirrel, Hystrix - Porcupine.
 
9. Order: Cetecea:
 
  1. Large aquatic animals.
  2. Body is spindle shaped and fish like.
  3. Hair is absent.
  4. Neck is absent.
  5. Fore limbs are modified into paddles.
  6. Hind limbs are absent.
 
Ex: Orcinus - Killer whale, Physeter - Sperm whale (Largest toothed whale) Plantanista – Dolphin
 
10. Order: Sirenia:
 
  1. These are all aquatic mammals. They are called sea - cows.
  2. Hind limbs are absent.
  3. Testis are abdominal.
 
Ex: Halicore dugong (dugong- sea cow), Trichecus (Manatee)
 
11. Order: Carnivora:
 
  1. They are terrestrial, arborial or aquatic mammals.
  2. Mammary glands are present on abdomen.
  3. The last premolar is called carnassial teeth.
 
Ex: 1) Panthera leo - Lion, 2) Pathera tigris - Tiger, 3) Acinomyx - Leopard, 4) Vulpes - Fox, 5) Trichecus - Walrus.
 
12. Order: Tubulidentate:
 
  1. Body is stout and pig like.
  2. Skin is covered by thick and less hair.
  3. Ears are long, errect and pointed.
 
Ex: Orycteropus
 
13. Order: Proboecide:
 
  1. Largest Terrestrial Mammals.
  2. Long probosis is seen.
  3. Incissors will become Tusks.
 
Ex: 1) Elephas - Indian elephant
 
14. Order: Hyrocoidea:
 
  1. Small Rabbit like
  2. Ears arc short
 
Ex: Procavis

15. Order: Perissodactyla:
 
  1. Single Looted mammal.
  2. The middle light of limbs will develop hoof.
 
Ex: 1) Equas (Horse), 2) Rhinoceros – Rhinoceros

16. Order: Artiodactyla:
 
  1. Terrestrial, semi aquatic animal.
  2. Limbs have two hooves.

Ex: Hippopotamus - Horse of River Camelus - Camel, Sus - Pig
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