Although the total number of species is relatively small, conifers are ecologically important. They are the dominant plants over large areas of land, most notably the taiga of the Northern Hemisphere, but also in similar cool climates in mountains further south. Boreal conifers have many wintertime adaptations. The narrow conical shape of northern conifers, and their downward-drooping limbs, help them shed snow. Many of them seasonally alter their biochemistry to make them more resistant to freezing. While tropical rainforests have more biodiversity and turnover, the immense conifer forests of the world represent the largest terrestrial carbon sink. Conifers are of great economic value for softwoodlumber and paper production.
The narrow conical shape of northern conifers, and their downward-drooping limbs, help them shed snow.
The earliest conifers in the fossil record date to the late Carboniferous (Pennsylvanian) period (about 300 million years ago), possibly arising from Cordaites, a genus of seed-bearing Gondwanan plants with cone-like fertile structures. Pinophytes, Cycadophytes, and Ginkgophytes all developed at this time. An important adaptation of these gymnosperms was allowing plants to live without being so dependent on water. Other adaptations are pollen (so fertilisation can occur without water) and the seed, which allows the embryo to be transported and developed elsewhere.
Conifers appear to be one of the taxa that benefited from the Permian–Triassic extinction event, and were the dominant land plants of the Mesozoic. They were overtaken by the flowering plants, which first appeared in the Cretaceous, and became dominant in the Cenozoic era. They were the main food of herbivorousdinosaurs, and their resins and poisons would have given protection against herbivores. Reproductive features of modern conifers had evolved by the end of the Mesozoic era.