Reptiles are four-legged vertebrates that lay amniotic eggs. They are ectothermic and have many adaptations for living on land such as tough skin and efficient lungs. Reptiles reproduce sexually and have internal fertilization, and their amniotic eggs have hard shells so that they can be laid on land. Reptiles are placed in four orders, and all are descendants of Sauropsida.
Reptile: Tetrapod vertebrate that produces amniotic eggs.
Tetrapod: Vertebrate with 4 limbs.
Keratin: A tough protein in the skin, feathers, nails, and other parts of tetrapod vertebrates.
Diaphragm: Muscle under lungs that control breathing.
Ectothermy: Body temperature is controlled from the outside through behavioral changes such as basking in the sun.
Cloaca: Body cavity that stores waste/gametes and has an opening that allows them to leave the body.
Amniote: Animal that produces eggs with internal membranes that allow gases but not water to pass through so the embryo can breathe without drying out (reptile, bird, or mammal).
Sauropsid: Early amniote that evolved into reptiles
Synapsid: Early amniote that evolved into mammals.
Reptiles have more adaptations for living on dry land than amphibians do.
2 types of early amniotes: synapsids and sauropsids