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ASHOK KUMAR BOLLAPALLI
LECTURER IN ZOOLOGY
KRK GOVT. DEGREE COLLEGE
ADDANKI-523201

 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

 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)

 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

 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.

 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

 It is classified into two sub classes
 Prototheria
 Theria
 Theria is subdivided into
 Metatheria and
 Eutheria

 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

 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

 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

 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

 Didelphis (oppossum)
 Dasyurus(Tiger cat)
 Coenolestes( Opossum Rat)
 Notoryctes( Marsupial mole)
 Parameles ( Bandicoot)
 Macropus(Kangaroo)
 Phascolarctos (Koala)

 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

 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))

 Chordate Zoology E.L.Jordan and Dr.P.S.
Verma S.Chand Publications
 Telugu Academy Zoology

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