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As the climate cooled, large forests died off, leaving open grasslands. Grasses flourished due to their ability to adapt to dry, arid conditions. Humans began to cultivate plants as a food source. Starting about 13,000 years ago, the earliest agriculture consisted of cultivating grass-type plants. These were grains such as wheat and barley. Later, ancient humans learned to cultivate corn, squash, beans, and new grains such as millet and rice.
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Grasses evolved during this period leading to the development of vast savanna ecosystems. The proliferation of grasses provided food for large, grazing mammals and protection for small animals such as rodents. Conifers dominated in colder climates, while angiosperms (flowering and fruiting plants) dominated in tropical climates.
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plants in which male or female reproductive organs are housed in a flower, proliferated and became the dominant plants. Modern-day trees appeared. Conifers continued to be important trees in colder regions. Ancestors of modern-day ferns evolved
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The climate became wetter, leading to development of large jungles where conifers dominated the landscape. Flowering plants appeared during this period, but they played only a minor role among other plants.
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Seed-bearing plants dominated over all others. Gymnosperms, such as cycads, ginkgos, and conifers, were the most prevalent plants of this period.
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The climate dried, leading to the advanced conifers. Widespread forestation appeared in some regions.
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Seed plants developed and colonized habitats where spore producing plants could not flourish.
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Plants developed sexual organs for reproduction, stems with vascular tissue, and woody tissue for structure. There came to be new ecosystems with more varieties of plants.
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The adaptation of vascular systems enabled land plants to stand upright and draw water upward through their structures.
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Most plants were in wet environments because most were non vascular. These plants reproduced by spores.
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Terrestrial plants started cooling the atmosphere because of such high volcanic matter.