Summary Reptilia

REPTILIA:




Adaptations of Amniotes:
 Amniotic egg:
 All amniotes have eggs with 4 extraembryonic membranes: the amnion, allantois, chorion and yolk sac
 Amnion encloses the embryo in fluid, cushioning the embryo and providing an aqueous medium for growth
 Metabolic wastes are stored in a sac formed by the allantois
 The chorion surrounds the entire contents of the egg and is highly vascularised
 The chorion and allantois form a
respiratory organ
 Amniotic eggs are surrounded by a
mineralised flexible shell which
forms a mechanical support and
semipermeable barrier to allow
passage of gases while limiting
water loss
 Yolk sac for nutrient storage
 Thicker and more waterproof skin:
 Thicker, keratinized skin that is less permeable to water
 Keratin gives the skin protection and limits water loss
 The epidermis contains a hard form of keratin called beta keratin
 Rib ventilation of the lungs:
 Amniote lungs are better developed than amphibians due to larger surface area
 Draw air into lungs by expanding thoracic cavity using costal muscles or pulling
diaphragm or liver posterior
 Stronger jaws:
 Expansion of jaw musculature provided better mechanical advantage when seizing large prey
 Their tongue is muscular and mobile