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Why did gymnosperms dominate many landscapes during the Mesozoic Era?

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Gymnosperm Pine cone and exposed seeds of the pinyon pine (*Pinus edulis*). Pinyon pines are gymnosperms and bear their edible seeds, known as pine nuts, in protective cones instead of fruit.

Gymnosperms dominated many landscapes during the Mesozoic Era primarily because of their evolutionary advancements in reproductive biology, which allowed them to colonize a wider range of habitats than their predecessors.1

Unlike earlier nonseed plants that were often restricted to moist environments, gymnosperms evolved the seed—a structure that protects the embryo within a seed coat and provides a self-contained environment for development. This innovation, combined with the development of pollen for fertilization, enabled these plants to thrive in drier terrestrial habitats that were previously inaccessible.1

Throughout the Triassic and Jurassic periods, gymnosperms underwent significant evolutionary radiation. They developed diverse mechanisms for pollination, seed protection, and seed dispersal, which increased their competitive success through natural selection. While they were eventually displaced by the rapid diversification of angiosperms during the Cretaceous Period, gymnosperms remained the dominant group of vascular plants for most of the Mesozoic, successfully adapting to the era's generally warm climate.123