By the end of the Cretaceous, flowering plants were reaching into most of the ecological niches across the globe, and were dominant in many . But obviously, the more primitive gymnosperms such as ferns and conifers survived, as they are with us today. While some of them, such as ginkgoes, have declined in diversity, they haven’t changed much in more than 100 million years.
Sequoias were apparently not well adapted to the polar regions, even though the climate was mild enough for plants to grow there. The closely related Metasequoia, or dawn redwood, was deciduous and lost its leaves in winter, so it had a more extended range. There may have been some hybridization between early Sequoias and Metasequoia, resulting in the modern coast redwood.
Redwoods seem to have thrived in the greenhouse conditions of the Cretaceous, but during the Cenozoic and up to the present, their range became restricted, presumably because of overall cooling that led to the glacial period of the past two million years or so. Sequoias have high water content in their tissues which makes them more susceptible to freezing than some other trees.
Sequoia cones were and are tiny compared to the massive sizes of the trees, but they are some of the most common fossils of sequoia. The name sequoia honors Sequoyah, the Cherokee who invented a system for writing the Cherokee language in the 1820s.
—Richard I. Gibson