Lizards and snakes
DBS 402B.2Presidency University, 2016
Amniotes
Reptilia•
First true terrestrial chordate
•
Limbs ending in claw•
Skin is covered with non-glandular scales
•
Proceolous
vertebrae •
Thecodont
teeth
•
Nucleated, biconvex RBC•
Metanephric
kidneys
Reptiles •
Class Reptilia
[Dry skin with epidermal scales; skull with one point of articulation with the vertebral column (occipital condyle); respiration via lungs; metanephric
kidneys; internal fertilization; amniotic eggs]–
Order Testudines
or Chelonia
[Teeth absent in adults and replaced by a horny beak; short, broad body; shell consisting of a dorsal carapace and ventral plastron.] Turtles.
–
Order Rhynchocephalia
[Contains very primitive; lizardlike
reptiles; well-developed parietal eye. A single species, Sphenodon
punctatus, survives in New Zealand.] Tuataras.
–
Order Squamata
[Recognized by specific characteristics of the skull and jaws (temporal arch reduced or absent and quadrate movable or secondarily fixed); the most successful and diverse group of living reptiles.] Snakes, lizards, worm lizards.
–
Order Crocodilia
[Elongate, muscular, and laterally compressed; tongue not protrusible; complete ventricular septum.] Crocodiles, alligators, Chorion
caimans, gavials.
Miller Harley
Squamata•
Skull with superior temporal fossa
•
The maxilla, palatine and pterygoid
are immovable (in lizards but movable in snakes) but quadrate is movable (more in snakes than lizards)
•
Teeth is either acrodont
or pleurodont•
Procoelous
vertebrae
The skull
The skull development
Skull, musculature in jaw movement
Lizards
Snakes
Lizard skull
Snake skull
The vertebrae
The difference
Lizards don’t have them
Lizard scale
Snake scales
Sum up?
Continued
Books
Kardong, Miller Harley, Linzey, Rastogy