In this article we will discuss about the classification of reptilia.
Reptilia # Subclass Anapsida:
Primitive Reptilia in which the bones of the skull join to form an uninterrupted roof.
Order Cotylosauria (extinct):
1. The vertebrae are gastrocentrous.
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2. The limbs are typically reptilian with five digits.
Examples. Diadectes, Procolophon, etc.
Order Chelonia:
1. The broad trunk is encased in bones forming a dorsal and a ventral shield within which the neck, head and limbs may withdraw.
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2. The sternum is absent.
3. The jaws are covered with a horny sheath and without teeth.
4. The nasal openings anterior.
5. The cloacal aperture is longitudinal, never transverse.
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Examples. Turtles, Tortoises, Testudo, Cistudo, etc.
Reptilia # Subclass Synapsida (extinct):
1. A pair of lateral openings (fenestrae) in the skull.
2. The teeth are usually heterodont.
3. Coracoids in the pectoral girdle are always two.
Examples. Anomodontia, Therapsida, etc.
Reptilia # Subclass Parapsida (extinct, aquatic):
1. A pair of dorsal openings (fenestrae) in the skull.
2. Most show two pairs of paddle like limbs.
3. The skull usually drawn to a long tapering rostrum.
Examples. Ichthyosaurus, Plesiosaurus, etc.
Reptilia # Subclass Diapsida:
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Two pairs of fenestrae in the skull on each side.
Order Rhynchocephalia:
1. The vertebrae are amphicoelous.
2. The quadrate immovable.
3. The premaxillae are paired.
4. Mandibular symphysis usually ligamentous.
Example. Sphenodon.
Order squamata:
1. The Vertebrae procoelous and the rib articulates with the backbone by a single head.
2. The lower jaw hinges upon a movable quadrate.
Suborder Lacertilia:
1. The epidermal scales are horny.
2. The quadrate bones are movable.
3. The skull is without a bony quadratojugal arch.
4. Copulatory organs paired.
5. Anal opening transverse.
Examples. Calotes, Lacerta, etc.
Suborder Ophidia:
1. Elongated, limbless reptiles with horny epidermal scales.
2. The quadrate bones are movable.
3. The rami of the mardible are united at the symphysis by an elastic ligament.
4. Copulatory organs are paired.
5. The anal opening is transverse.
Examples. Snakes, Python, Naja, etc.
Order Crocodilia:
1. The palate is hard.
2. The quadrate bones are immovable.
3. A quadratojugal arch is present.
4. The teeth are implanted in alveoli of the jaws.
5. The ventricle is divided by a complete septum.
6. The anal opening is longitudinal.
Examples. Crocodiles, Alligators, Crocodylus, Gavialis, etc.