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You may know that you are related to apes and monkeys. But did u know that you are
also related to bats, tigers, whales, kangaroos, and many more creatures?
“Mammals”
Presenters: Pema Khandu
Phub Lhamo
Tshering Lhamo
Describe different classes of mammal with examples
Kingdom Animalia---Phylum Chordata------Subphylum Vertebrata---------Class Mammalia
What is mammals?
• Mammals are animals that have hair, are warm-
blooded, and nourish their young with milk.
General characteristics of mammals
• Warm blooded animals.
• Skin is more or less covered with hairs except
Cetacea.
• Sudoriporous (sweat) glands and sebaceous (oil)
glands are present in the skin.
• Mammary glands in females to nourish the young
ones.
• External ear (pinnae) are present.
• Teeth are heterodont (differentiated into
incisors, canines and molars), thecodont
(embedded in the alveolar pockets of jaws) and
diphyodont (only 2 sets of teeth, milk set
replaced by permanent set).
• Skull with two occipital condyles which are
formed entirely by exoccipitals.
• The lower jaw is composed of a single bone, on
each side
• Vertebrae are gastrocentrous composed of three
pieces, the centrum, and two epiphyses.
• With few exceptions mammal possess seven cervical vertebrae.
• The digits in the fore and hind limbs are never more than 5, but often reduced.
• Presence of muscular diaphragm between thoracic and abdominal cavities.
• Heart is four chambered with only one left aortic arch.
• RBC are non-nucleated.• Brain with four optic lobes.• Kidney is metanephros.• Penis is always present.• Viviparous (the young develops in the uterus for
some time and born alive).
Three classes of Mammals
1. Prototheria (Monotremes): are primitive egg-
laying mammals.
2. Metatheria (Marsupials/pouched mammal):
their young are born in an extremely immature
state.
3. Eutheria (Placental mammals): their young are
born at an advanced state.
Prototheria (Egg laying mammal)
Primitive mammalsConnecting link between the reptile and mammal
General characteristics Skeleton resembles that of reptile No external pinna present on the ear Teeth are present only in the young, adults with
horny beak A cloaca is present into which ureters and
urinogenitals sinus open Mammary glands are without nipples The pectoral girdle possesses large coracoid
bones and interclavicle
The pelvic girdle possesses epipubic bones extending
from the pelvis
Vertebrate are without epiphyses
The ribs have only a single head, the tuberculum being
absent
In the skull , tympanic bulla and lacrimals are absent ;
the jugal is reduced or absent
There is no corpus callosum in the brain
The cochlea is a simple process of the sacculus and not
coiled
Testes are abdominal
Females are oviparous
Found in Australia, Tasmania and New Guinea
Examples of prototheria
Echidna (spiny ant eater) Ornithorhynchus (Duck-billed
platypus)
Metatheria (pouched mammals)
General characteristics• Young ones are born prematurely after very short
gestation• Marsupium or rood pouch is present in the
females• Mammary glands are sebaceous and bearing
nipples• Epipubic (marsupial) bones are usually present
and attached with the pubis• Separate coracoid and interclavicle are absent• Ribs bear two heads, tuberculum and capitulum
• Vertebrae with epiphyses• Corpus callosum is feebly developed or absent.• Vagina and uterus are double (didelphic condition)• Viviparous• Placenta is usually absent.
Examples
Didelphis (Opossum) Dasyurus (Tiger-cat)
Eutheria Placental mammalGeneral characteristics Give birth to young one Marsupium (marsupial pouch) is entirely absent. Mammary glands are well developed with
nipples. Epipubic bones are absent. Ribs bear two heads, tuberculum and capitulum. Clooca is absent. Corpus callosum is present Urinogenital organs open independently of the
rectum. Testes are usually contained in scortal sacs.
Warm blooded External pinna present Viviparous. The young always nourished for a
considerable time in the uterus by means of allantoicplacenta and born in a relatively advanced state.
Examples
• Insectivorous mammal- shrew,moles
• Aerial mammal – bat
• Aquatic mammal-whales
• Carnivorous mammal-tiger
• Hoofed mammal- horse
• Mammal with proboscis-elephant
• Primates-apes, monkeys
References
Verma, P.S. (1984). A manual of Practical Zoology:
Chordates. New Delhi: S. Chand & Company
Ltd.
Newman, H.H. (1981). The Phylum Chordata. Agra,
India : Satish Book Enterprise.
Thank you !