3. It’s a subclass of class reptilia
It includes all living reptiles
Turtles are excepted
It also includes reptiles that ruled the
land, air and sea during the Mesozoic era
What are diapsids?
4. presence of two openings on each side
of the skull
the upper and lower temporal openings
General characteristics
5. allows for the attachment of
larger, stronger jaw muscles, and enables
the jaw to open more widely
long slender feet with overlap in the bases
of the wrist and toe bones
General Characteristics
6. relatively long lower arm bone
(the radius) compared to the upper arm
bone (humerus).
11. Primitive lizard-like reptiles
They have quite different
scales, teeth, and internal morphology
than modern lizards.
Retained the Diaspid skulls from their
ancestors
Acrodont dentition (teeth fused to
jawbones)
The only surviving Rhynchocephalian is
Sphenodon
Rhynchocephalia
12. Sphenodon
Feeds on small vertebrates
Attains a length of 0.75m (2.5ft)
Sexually mature @ 20 yrs. Old
Life span may exceed 60 years
The upper surface of the body is
covered with small granular scales
and the lower surface is covered
with transverse rows of large
squarish scales.
Operate at very low body
temperatures (between 6 and 16 C)
Acrodont dentition
13. Composed of lizards , snakes and amphisbaenians
2 Characteristics that unite squamates:
Periodic shedding of skin
◦ snakes shed their skin in one piece
◦ Lizards and amphisbaenians shed their skin in patches
uniquely jointed skulls and jaws
◦ both strong and flexible
◦ extraordinary jaw mobility of squamates enables them
to open their mouths very wide
◦ consume large prey
Squamata
14. Well developed appendicular muscles
Suitably constructed skeleton
Run agilely on their hind limbs
Some are broad jumpers
Suction discs on toes
◦ Adhere to smooth vertical surfaces
◦ Geckoes
Other Characteristics
15. Glide through air
◦ Due to rib supported extensions of the lateral
body wall
◦ Draco, the flying dragon
16. Few lizards are either limbless or have only
vestiges of limbs
Some lizards are blind
Spectacles-transparent eyelids
Nicitating membrane – 3rd eyelid
◦ Protection and moisture for the eye w/o blocking
vision
17. Snakes evolved from lizards
◦ Lost limbs
◦ Acquired other modes of locomotion
Lateral progression- lashing of body back and
forth causing lateral waves that force longitudinal
motion. To put it another way: They go forward
by moving sideways.
◦ Large ventral scales or scutes
◦ Viviparous
Giving birth to living offspring that develop within
the mother's body.
18.
19. Amphisbaenians are subterranean lizards
◦ Limbless
◦ Annulated bodies similar to apodans
◦ Drum and eyes are covered with opaque skin
20. much greater degree of bone in the skull
Internally, their right lung is reduced in
size to fit their narrow bodies
distinctive single median tooth in the
upper jaw.
carnivorous
They move using an accordion-like
motion
