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Zoology
CLASSIFICATION OF MAMMALS: THERIA
By BS MediaTwitter Profile | Updated: Saturday, 01 July 2017 21:00 UTC
THERIA
This group includes Mammals which show true mammals characters
Infraclass Metatheria:
They show almost all the Mammalian characters.
- Females show brood pouch or Marsupium on their ventral abdomen.
- Sebaceous glands are modified into mammary glands.
- Pelvic girdle shows epipubic bones. This supports Marsupium.
- Ribs are two headed.
- Carpus callosum is absent.
- Vagina and uterus are double (didefphic condition)
- They give birth to immature young ones.
- 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:
- Mammary glands are well developed.
- Double headed ribs are seen.
- Carpus callosum is present.
- Urinogenital organs will open independently into the Rectum.
- Testis are extra abdominal.
- Uterus and vagina are single.
- They show placenta in the development of embryo. This infra class is divided into following orders.
1. Order: Insectivora:
- Small animals are seen in this order.
- Snout is long.
- Five toed feet are seen.
- They are Nocturnal and Terrestrial
Ex: 1) Paraechinus (Hedgehog), 2) Talpa (mole), 3) Echinosorex (Shrews)
2. Order: Dermopetera:
- 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.
- They are Nocturnal.
Ex: Galeopithecus (Flying lemur)
3. Order: Chiroptera:
- Fore limbs are modified wings.
- Hind limbs are weak.
- Digits are clawed.
- Eyes are small and vision is very weak.
- They are usually called Bats.
Ex: Pteropus (Flying fox), Megaderma (Vampire bat)
4. Order: Primates:
- Hands and feet are more or less prehensile.
- Thumb is oppossable to other digits.
- Only two pectoral mammary glands are present.
- 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:
- Feet has 5 digits. They are clawed.
- Testis are abdominal.
Ex: 1) Dasypus = ormadilla, 2) Bradypus = Three toed sloth, 3) Myrmecophaga' = Giant ant eater
6. Order: Pholidota:
- The body is covered by scales.
- In between scales hairs are present.
- Teeth are completely absent.
- Tongue is long, sticky and protrusible (Helpful to catch the ants).
Ex: 1) Manis (scaly ant eater or parigolin)
7. Order: Lagomorpha:
- Small mammals
- Tail is short.
Ex: Oryctologus - Rabbit, Lepus (Hare)
8. Order: Rodentia:
- Small mammals.
- Canines are absent. (Diastema is present)
Ex: Ratus ratus - Rat, Funambulus - Squirrel, Hystrix - Porcupine.
9. Order: Cetecea:
- Large aquatic animals.
- Body is spindle shaped and fish like.
- Hair is absent.
- Neck is absent.
- Fore limbs are modified into paddles.
- Hind limbs are absent.
Ex: Orcinus - Killer whale, Physeter - Sperm whale (Largest toothed whale) Plantanista – Dolphin
10. Order: Sirenia:
- These are all aquatic mammals. They are called sea - cows.
- Hind limbs are absent.
- Testis are abdominal.
Ex: Halicore dugong (dugong- sea cow), Trichecus (Manatee)
11. Order: Carnivora:
- They are terrestrial, arborial or aquatic mammals.
- Mammary glands are present on abdomen.
- 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:
- Body is stout and pig like.
- Skin is covered by thick and less hair.
- Ears are long, errect and pointed.
Ex: Orycteropus
13. Order: Proboecide:
- Largest Terrestrial Mammals.
- Long probosis is seen.
- Incissors will become Tusks.
Ex: 1) Elephas - Indian elephant
14. Order: Hyrocoidea:
- Small Rabbit like
- Ears arc short
Ex: Procavis
15. Order: Perissodactyla:
- Single Looted mammal.
- The middle light of limbs will develop hoof.
Ex: 1) Equas (Horse), 2) Rhinoceros – Rhinoceros
16. Order: Artiodactyla:
16. Order: Artiodactyla:
- Terrestrial, semi aquatic animal.
- Limbs have two hooves.
Ex: Hippopotamus - Horse of River Camelus - Camel, Sus - Pig
End of the article