Class Reptilia amniotic eggs with a thick protective shell powerful jaws and limbs internal fertilization tough, dry, scaly skin 3 chambered heart (4 in crocodilians) efficient lungs

Amniotic Egg

Evolution of the Legs

The Origin and Adaptive Radiation of the Reptilian Groups Evolution of the Cranium

The Origin and Adaptive Radiation of the Reptilian Groups The Anapsids

The Origin and Adaptive Radiation of the Reptilian Groups The Diapsids

The Origin and Adaptive Radiation of the Reptilian Groups The Synapsids

Subclass Anapsida Order Testudines: The Turtles dorsal carapace, ventral plastron lack a diaphragm poor hearing & vocalization lack teeth (sharp beak)

Reproduction bury eggs on land sex is determined by development temperature (cold  males)

kinetic skull Subclass Diapsida Order Squamata Lizards, Snakes, & Worm Lizards

Lizards moveable eyelids external ear skin lacks glands Worm Lizards entirely limbless numerous vertebrae no moveable eyelids Jacobson’s organs Snakes burrowers lack external limbs ears & eyes hidden under skin

Lizard Behavioral Adaptations

Jacobson’s Organs

Snake Reproduction oviparous ovoviviparous viviparous Snake Venom neurotoxin hemotoxin Hemotoxin video

The Tuatara Order Sphenodonta represents one of the slowest rates of evolution known among vertebrates

Features in Common with Fossils diapsid skull “third” eye

Order Crocodilia The Crocodiles & Alligators like Tuatara, remained relatively unchanged over 200 m.y. bury eggs on land (cold  females) with birds, only surviving representatives of archosaurians

Crocodilian Circulation