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REPTILES
 Scientific Classification of Reptiles
 To creep
Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class: Reptilia
REPTILES
 REPTILES
 tetrapods - 4 legs adapted for land, hip/girdle
 Amniotes - animals whose embryos are surrounded
by a fluid filled amniotic membrane
 Four surviving orders:
 Crocodilia (crocodiles, caimans and
alligators): 23 species
 Sphenodonta (tuataras from New Zealand):
2 species - Wedge Tooth
 Squamata (lizards, snakes and Worm
lizards) approximately 7,600 species - scaly
skin
 Testudines (Tortoise) Chelonia (Turtles :
approximately 300 species – to seize
Firs known reptile fossil
 350 MYA
 Carboniferous period
 Drier conditions gave rise to the first
adaptive radiation of reptiles
 by late Triassic and Jurassic periods
 Age of Reptiles – Mesozoic
 245 MYA
REPTILES
Reptiles are found on every continent except
for Antarctica,
main distribution comprises the tropics and
subtropics.
modern species of reptiles do not generate
enough heat to maintain a constant body
temperature and are thus referred to as
"cold-blooded" (ectothermic).
REPTILES
Sea Turtle an exception: a reptile that
elevates its body temperature well above
that of its surroundings.
REPTILES
Reptiles evolved from tailed amphibian ancestors. There
are nearly 8000
 A reptile has the following features;
ectothermic
dry, scaly skin
tough shell on eggs
eggs are laid on land - “enclosed the pond”
REPTILES
 The Rise of Amniotes - Reptiles
During the late Carboniferous, amphibians
gave rise to the amniotes (birds, reptiles, mammals).
A. Four features were critical to amniotes’
escape from water dependency:
1. They produce amniote eggs with internal
covering membranes and a shell, which allow
the eggs to survive in dry habitats.
REPTILES
 Amniote egg contains a membraneous sac
that surrounds and protects the embryo.
REPTILES
 Allantois
Greek word for sausage
respiration and excretion
webbed with blood vessels.
liquid waste from the embryo.
REPTILES
The allantois functions similarly in
monotremes, which are egg-laying
mammals.
REPTILES
3 They have internal fertilization.
4 Their kidneys are good at conserving
water.
5 scaly skin water conservation
REPTILES
B.
“Reptiles” demonstrate certain advantageous
features compared to amphibians.
Modification of limb bones, teeth, and
jaw bones allowed greater exploitation
of the insect life
Development of the cerebral cortex permitted
greater integration of sensory input and motor
response.
Well developed lungs
REPTILES
Descendants of the surviving dinosaurs
became the lineage of reptiles.
4 living orders
REPTILES
 Circulatory systems
Fish
Bird, Mammal
Reptile
Amphibian
REPTILES
Humans, birds, and mammals have a 4chambered heart that completely separates
oxygen-rich and oxygen-depleted blood.
Fish have a 2-chambered heart in which a
single-loop circulatory pattern takes blood
from the heart to the gills and then to the
body.
Amphibians have a 3-chambered heart with
two atria and one ventricle.
REPTILES
The disadvantage of the three-chambered heart is
the mixing of oxygenated and deoxygenated
blood.
Most reptiles have an incomplete division in the
ventricle
“ 3 ½ chambers”
Crocodiles and alligators have 4 complete chambers
REPTILES
 A Sampling of Existing Reptiles – (Latin, to creep)
A. Turtles – Testudines
1. The distinctive shell offers protection while
conserving water and body heat.
REPTILES
2. The shell is connected to the skeleton.
Their teeth are tough, horny plates
designed for gripping & chewing
food.
3. Turtles lay their eggs on land, where
predation is high.
REPTILES
 Anatomy of a Box Turtle
REPTILES
 Turtle shell structure
REPTILES
 Turtle eggs and newborn
REPTILES
B. Lizards
1. Most lizards are small-bodied insect
eaters; their most usual habitats are deserts
and tropical forests.
2. Lizards are also prey for many other animals,
but are quick in movement and have the
unique ability to sever their own tails if it is
grabbed by a predator.
REPTILES
 Lizards
REPTILES & AMPHIBIANS
 Scientific classification
Order: Squamata
95% of all living reptiles are in this group
REPTILES & AMPHIBIANS
C.
Snakes
1. Snakes are limbless but retain vestiges
of hind limbs; they are excellent
predators.
2. Snakes have the ability to swallow prey
larger than they are due to flexible skull
and jaw bones.
3. All snakes are carnivores. Some suffocate their
prey, and some kill their prey with venom.
REPTILES & AMPHIBIANS
95% of all living reptiles are composed of
Lizards and Snakes.
REPTILES & AMPHIBIANS
D. Tuataras
1. Although they resemble lizards, they
are evolutionarily more ancient. They
resemble amphibians with the brain
and the way they walk.
2. They do not engage in sex until they
are twenty years old!.
REPTILES & AMPHIBIANS
3. Only two species remain today;
they live on islands off the shore of
New Zealand.
4. Like lizards, tuatarus have a 3rd eye
under the skin with a retina, a lens,
and nerves to the brain. They also
may live to be 60 years old.
REPTILES & AMPHIBIANS
 Scientific Classification of Tuataras
Order: Sphenodontia
REPTILES & AMPHIBIANS
E.
Crocodilians
1. Crocodiles and alligators all live in or
near water.
2. They are the largest living reptiles.
3. The body plan includes a long snout;
body temperature is regulated behaviorally (ectothermic).
REPTILES & AMPHIBIANS
4. The ventricle of the heart is divided
into right and left chambers – more
like the heart of birds than that of
other reptiles.
REPTILES & AMPHIBIANS
4. Like other reptiles and birds, crocodilians
adjust body temperature with behavioral and
physiological mechanisms.
5. They are like birds in displaying complex social
behaviors, such as parents guarding nests
and assisting hatchlings into water. This trait
and others suggest that crocodilians and birds
share a common ancestor.
REPTILES & AMPHIBIANS
 Reptilian Orders
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Procolophonida (extinct)
Araeoscelidia (extinct)
Avicephala (extinct)
Younginiformes (extinct)
Ichthyopterygia (extinct)
Placodontia (extinct)
Nothosauria (extinct)
REPTILES & AMPHIBIANS
 Orders (cont.)
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Plesiosauria (extinct)
Prolacertiformes (extinct)
Pterosauria (extinct)
Saurischia (extinct)
Ornithischia (extinct)
REPTILES & AMPHIBIANS
 Reptilian Orders (cont.)
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Testudines
Squamata
Sphenodontia
Crocodilia