Amniotes Eggs with 4 membranes Have dry, tough or scaly skin 2 kidneys Groups Synapsids – all mammals Sauropsids – reptiles and birds

27 Jan. 2010Reptiles.ppt2 Amniote egg Embryo develops membranes within shell  amnion, chorion, yolk sac, allantois Shell permeable to air (breathes) Amnion, chorion retain water to keep embryo wet.

Reptiles No longer a formal taxon, not monophyletic  Refer to lineages that show basic amniote features, but not derived traits of birds/mammals Chase prey Well-muscled jaws 4 limbs good at supporting weight Lungs Bigger brains

General Characteristics Live in a variety of land and water habitats Cold-blooded Both sexes have cloaca – functions in excretion and reproduction adaptations to terrestrial environment  Keratinized skin - epidermal scales- reduce water loss abrasion resistant  Internal fertilization- Sperm deposited in female body

Groups Crocodilia (crocodiles, gavials, caimans, and alligators) Sphenodontia (tuataras from New Zealand) Squamata (lizards, snakes, and worm lizards): Testudines (turtles and tortoises):

Turtles Bony or cartlingous shell attached to skelton Horny plates act as teeth Vunerable because of predators, hunting, nesting site destruction

Lizards Largest order Skin has horny scales or sheilds

Snakes Limbless, can have vestigial structure Snakes can open jaw to accomodate large prey May use venom to subdue prey Lack eyelids, external ears Females store sperm and lay several clutches

Tuataras Two species surviving in New Zealand Resemble amphibians in brain and locomotion Have 3 rd eye under skin  May detect daylentgh and light intensity

Crocodilians All are predators in/near water Powerful jaw, long snout, sharp teeth Only ones with a 4 chambered heart like birds and mammals Engage in parental behavior Closest relatives to birds