Practice question

Development of amniotic egg freed vertebrates from aquatic breeding constraints enabling colonization of dry terrestrial habitats far from ponds and streams for reproduction representing pivotal synapomorphy. Amnion prevents desiccation, protective shell or uterine membranes plus chorion enable gas exchange, allantois handles waste, keratinized epidermis reduces evaporative loss, costal ventilation replaces cutaneous breathing. Consequently amniotes became first truly terrestrial tetrapods able to lay eggs inland or retain embryos internally, exploit deserts and arboreal niches unlike amphibians requiring moist sites for external fertilization and aquatic larval development vulnerable to drying.