2. Endothermic terrestrial Vertebrates that dominated
during Cenozoic era
Originated from theropsid reptiles in Triassic period
Occupy the top of evolutionary ladder due to their
superiorly organized brain
Largest mammal- Balanoptera musculus- 35 meters
long and 120 tones weight
Largest land dwelling mammal- African Elephant-
Elephus maximus
Longest Mammal-Giraffe-16 feet- Giraffa
camelopardalis
Smallest mammal- Etruscan Pygmy Shrew
Bumble bee bat
3. Endothermic/Homeothermic/Warm blooded
Epidermal hair, spines, horns, hooves, antlers,
nails, claws
Integumentary gland- Sudorific/Sweat glands-
Regulates temperature, Sebaceous glands-keeping
the skin and hair soft
Mammae- modified sudorific glands- helps to nourish
the young one with nipples/ teats
Diaphragm- muscular partition – separates thoracic
and abdominal cavities-helps in breathing
Dentition is- heterodont( Inscisors, canines,
premolars and molars), diphyodont( teeth forms
twice in the life-Milk teeth/deciduous teeth
replaced by permanent teeth) and thecodont( teeth
lodged in the deep sockets of the jaw bone)
4. Salivary glands in the buccal cavity are four
pairs-parotid, Sub maxillary/Sub mandibular,
Sub lingual and infra orbitals(absent in Man)
Skull is dicondylic, Each half of the jaw bone is
composed of a single bone, the dentary,
articulating with the sqamosal of the skull, A
bony secondary palate formed by the union of
premaxillae, maxillae and palatine bones,
separates nasal and oral passages. Vertebrae are
with flat centrum(Acoelous/ Amphiplatyan).
Ribs double headed, Cervical vertebrae are
seven except in three toed sloth(9), two toed
sloth(6) and manatee(6)
Respiration is by lungs, glottis is guarded by a
flap called epiglottis
5. RBC are enucleated, boconcave and circular
except in Camels and Llamas where they are
elliptical. SAN pacemaker, AVN- Ectopic
pacemaker-behaves as pacemaker when SAN fails,
Heart four chambered, double circulation, two
aortic arches, Renal portal system is absent
Kidneys are Metanephric. Excretes urea- ureotelic
Cerebral hemispheres-large and exhibit
convolutions. Carpus callosum- transverse band
that connects cerebral hemispheres. Corpora
quadrigemina- optic lobes four. Cerebellum is large,
cranial nerves are 12 pairs
Eyes are with lacrimal, harderian and meibomian
glands whose secretions moisten and lubricate the
conjunctival surface of the eye ball and its lids.
6. Ear is divided into three regions external ear/pinna-
contains ceruminous glands in the auditory meatus-
absent in monotremes, cetaceans and sirenians. Middle
ear has three ossicles extending between tympanum
and internal ear- Malleus, incus and stapes- stapes is
the smallest bone in mammals. Internal ear has three
semicircular canals and a watch spring like cochlea,
conatining organ of corti
Testes –scrotal sacs except in whales, elephants and in
some insectivores and all prototherians
Eggs are microlecithal or alecithal except in
monotremates( Megalecithal)
Holoblastic unequal cleavages
Viviparous ( except in Prototherians- oviparous),
placenta- helps in protection , nutrition respiration and
excretion. Chorioallantic placenta in Eutherians and
chorioyolksac placenta in marsupials, Gestation
period- intrauterine period
7. It is classified into two sub classes
Prototheria
Theria
Theria is subdivided into
Metatheria and
Eutheria
8. Reptile like, oviparous egg laying mammals with a
variable temperature between 25-28 degrees Celsius
Found in Australia, Tasmania, New Guinea
No pinna on the ear
in the skull tympanic bulla and lacrimals are absent; the
jugal is reduced/ absent
Teeth are present only in young ones adults are edentate
and are with horny beak
The pectoral girdle possesses large coracoid bones and T-
shaped interclavicle.
The pelvic girdle possesses epipubic bones, vertebrae
without terminal epiphyses
9. The ribs are single headed
Cloaca into which ureters and urinogenital
sinus open
Mammary glands are without nipples
No corpus callosum
The cochlea is a simple process of the
sacculus and not coiled
Testes are abdominal
Females are oviparous
10. Modern viviparous marsupials and placental
mammals
Ear with pinna
Mammary glands with nipples/ teats
Dentate. Vertebrae with terminal epiphyses
Cloaca is absent
Testes are in scrotal sac. Vasa deferentia and air
bladder opening through a common urethra in
penis
Ureters open into the base of bladder
Oviducts open into a vagina
It is divided into two infraclasses
Metatheria and Eutheria
11. Marsupium/ brood pouch
Mammary glands bearing nipples are sebaceous
Epipubic bones are present and attached with the
pubis
Separate coracoid and interclavicle are absent
Corpus callosum is feebly developed or absent
Vagina and uterus are double/Didelphic condition
Penis is bifid
Placenta is rudimentary yolksac type
Young ones are born extremely immature and
crawl into marsupium attached with nipples for
further development
Confined to Australian region-Land of Marsupials
13. Higher viviparous placental mammals
Marsupium is entirely absent
Epipubic bones are absent
Cloaca is absent
Corpus callosum is present
Testes are usually contained in scrotal sacs
Vagina is single
Young one always nourished for considerable
time in the uterus by means of chorio-allontoic
placenta and born in a relatively advanced state
Echolocation-emit ultrasounds to locate their
way- Bats and whales
14. Insectivora( hedgehogs Shrews mole)
Chiroptera (Bats and flying foxes)
Primates( Man and apes)
Edentata(sloth, Armadillos American ant
eaters(Myrmecophaga))
Rodentia( Rat)
Cetacea(Whales and Dolphins)
Carnivora(Dogs,Cats Tigers Lion and bears)
Sirenia(Manatees=Trichechus)
Logomorpha (Rabbit)
Pholidota(Manis(Pangolin/Scaly ant-eater))
15. Chordate Zoology E.L.Jordan and Dr.P.S.
Verma S.Chand Publications
Telugu Academy Zoology