reptilian characters

1. General Characteristics
of Reptiles

2. Diverse group of animals
◦Lizards
◦Snakes
◦Tortoises
◦Crocodiles
◦Extinct dinosaurs etc.

4. From a latin word
"reptilis" meaning
"creeping“
Repere or reptum
means creep/ crawl

5.  Herpatology- study of reptiles
 Smallest reptile- dwarf gecko
Sphaerodactylus aurieus(16mm)
 Largest reptile living-
Crocodylus porosus(20.6 feet, over
1900kgs)
 Golden age of reptiles-
Mesozoic era

7. First vertebrates which
became independent
of water and took
possession of dry land

8. Complete colonization of
land was achieved by the
reptiles, which can lay
their eggs on dry land.
Amniotes-Amnion and
allantois

9. Originated in Carboniferous
period from labyrinthodont
Amphibian stock
Flourished during Mesozoic
era- Golden age

10.  Terrestrial organisms
 Poikilotherms
 Tetrapods-
pentadactylous limbs
 Digits end in claws

11.  Body -head, neck , trunk
and a tail
 Body –dry, water proof
epidermal scales-
epidermal in origin,
osteoderms beneath
horny scales- crocodiles
 Skin– few glands(musk
glands, femoral glands,
etc) or no glands
 Dermis -
chromatophores

12.  Skull bears single
condyle
 One or two temporal
fossae are usually found
 Pineal foramen is present
in the skull
 Teeth are simple, conical
and thecodont
 Ribs single headed
 Gastralia(abdominal ribs)
rob like membrane
bones-ventral body

13.  Coelom-Pericardial cavity & Pleuro
peritoneal cavity
 Dentition Homodont, Acrodont and
polyphyodont

14.  Pulmonary
respiration i.e.
respiration through
lungs takes place
 Intercoastal muscles
assist in respiration
 Cloacal respiration –
turtles
 Cutaneous gas
exchange in many
turtles, sea snakes

15.  Heart consists of a
sinus venosus, 2
auricles and 1
incompletely divided
ventricle
 Has both left and
right systemic arches
 Hepatic and Renal
portal systems
 RBC-Oval and
Nucleated

16.  Metanephric kidneys with no
nephrostomes
 Uricotelic
 Cloaca with three chambers-
Coprodaeum(opening of large intestine),
Urodaeum(openings of the Excretory and
genital ducts)& Proctodaeum opens out
by cloacal aperture

17.  Two meninges- the duramater and the
pia-arachnoid membrane
 12 pairs of cranial nerves seen
 Tympanic membrane in external auditory
meatus, middle ear with single ossicle-
Columella auris
 Third eyelid nictitating membrane present
in most
 In Snakes-Jacobson’s organs (vomeronasal
organs)

18.  Sexes are separate
 Males possess
copulatory organs
 Fertilization is
internal
 Large eggs with
considerable yolk
 Eggs covered by
porous calcareous
shell(cleidoic &
megalecithal)
 Cleavage -
meroblastic

20.  Embryo develops
within embryonic
membranes –
amnion and
allantois
 Most reptiles are
oviparous
 Some snakes are
viviparous

21. Thank You