01:119:115 Lecture Notes - Lecture 7: Amniote, Golden Algae, Charophyta
8 Jul 2015
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Document Summary
Some tetrapods evolved eggs adapted to survive on land: the amniotes. The major derived character of this group is the amniotic egg: amniotic egg has 4 specialized membranes (extraembryonic membranes) Amnion is a layer that forms fluid filled sac around embryo; protects embryo: eggs have shell that reduce dehydration; facilitated moving away from water, use rib cage for ventilating lungs, two lineages of amniotes: Lay eggs on land: fertilization is internal, ectothermic (rely on external environment for heat regulation, e. g. lizards, tuataras, snakes, crocodiles, birds, dinosaurs. Mammals are amniotes that have hair and produce milk. Have mammary glands that produce milk for offspring (sugars, proteins, fats, minerals, vitamins) Have hair of keratin and have fat layer under skin to retain heat. Are endotherms: produce heat during metabolism of nutrients; high metabolic rate. Have large brains and a muscle (diaphragm) to help breath. Different size teeth for various functions including shearing, crushing and grinding. 3 major lineages: monotremes (egg laying mammals)
