Reptiles first evolved around 310-320 million years ago during the Carboniferous period and have since diversified greatly. They are air-breathing vertebrates with lungs, scaly skin to prevent drying out, and leathery eggs to prevent drying. Common characteristics include being ectothermic, having lungs and 3-chambered cloacas, and excreting uric acid. Reptiles include snakes, lizards, crocodiles, turtles, and tortoises and there are over 6,000 living species worldwide.

1. Presented by
MUHAMMAD AKMAL
BHIKH

2.  The reptiles aroused about 310 -320
million years ago, during the
carboniferous period.
 Reptiles have extreemly diverse
evotionary history that has led to the
origin of the reptiles.

3. The world reptile is derived from a latin world rept –means
crawled.
DEFINITION.
A verteberate animal of a class that includes snakes ,lizards
,crocodiles ,turtles and tortoises..
Appeared more than 300 million years ago.
 GENERAL CHARACTERS.
 Evolved to be suited for life on land.
 Lungs.
 Leathery egg shell to prevent drying out.
 Ectothermic cold blooded.
 Skin is covered with scales to prevent drying out.

4.  General Characteristics of Class Reptilia:
 Some of the general characters of class Reptilia are listed
below:
 1. Reptiles are the creeping and burrowing cold blooded
vertebrates bearing epidermal scales. They are ectothermic
(cold-blooded) and are found mostly in the warmer parts
of the world. They are few in colder parts. They are mostly
terrestrial animals. There are about 6,000 living species of
reptiles in the world.
 2. Skin is dry, rough and without glands, bearing
epidermal scales or scutes.
 3. Snakes and lizards shed their scales as skin cast.
 4. They do not respire by means of gills. Respiration
always takes place through lungs. Ribs help to expand and
contract the body cavity, making the

5.  3 chambered cloaca present.
 Uricotelic excretion.
 Metanephric kidneys.
 Cranial nerves 12 pairs except snakes which have
10 pairs.
 Sexual dimorphism is present.
 Fertilization is internal.
 Eggs are cleidic large yolky eggs with calcarious
shell.
 No larval stages .
 Amniotes ,all 4extra embryonic membrane
present.m

6.  Limbs are clawed when present.
 Cold blooded poikilothermic.
 Exoskeleton of horny scales skutes or bony
plates.
 Skin dry cornified and non glandular.
 Skull is monocondylic .
 T -shaped interclavicle present .
 Heart is four chambered in crocodiles but 3
chambered in others members of reptiles.
 Heart with two auricles and two ventricles
found in crocodiles.
 R.B.C.oval and nucleated.

7. Phylum chordata
Sub phylum ….vertebrata.
Class reptilia.
Order squamata-lizards and snakes.
Order testudine-turtles and tortoise.
Order crocodilia-crocodiles and aligators.

8.  Class- Reptilia
 Subclass –anapsida –order
chelonia.
 Subclass diapsida
 -order- rhynchocephalia-
 -Order-squamata
 Order crocodilia

10.  3 chambers
 The frog heart has 3 chambers: two atria and
a single ventricle. The atrium receives
deoxygenated blood from the blood vessels
(veins) that drain the various organs of the
body. The left atrium receives oxygenated
blood from the lungs and skin (which also
serves as a gas exchange organ in
most amphibians).

11.  Heart anatomy.
It has a four-chambered heart and two ventricles, an
unusual trait among extant reptiles, and both a left and
right aorta which are connected by a hole called the
Foramen of Panizza. Like birds and mammals, crocodilians
have heart valves that direct blood flow in a single direction
through the heart chambers.

15.  Introduction –www.google.com
 Historical perspectives –google chroom.
 Description –www.biological sciences.com
 General character-
https//www.google.com.pk
 Classification –https//www.google.com.pk
 Images-https//www.google.com.pk