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During the Jurassic Period, a genus of cone-bearing evergreen trees now named Wollemia lived on the supercontinent Gondwana. These ancient trees were long known only from the fossil record, and were thought to have been extinct for 150 million years — until 1994, when a few survivors of one species were found living in a temperate rainforest at Australia's Wollemia National Park.

That species, Wollemia nobilis, is often described as a living fossil. Only about 80 mature trees are left, plus some 300 seedlings and juveniles, and the species is listed as critically endangered by the International Union for Conservation of Nature.

While Wollemia nobilis is the last of its genus, there are also still other middle Mesozoic trees alive today. Ginkgo biloba, aka the ginkgo tree, dates back about 200 million years and has been called "the most ancient living tree."

From about 420 million to 370 million years ago, a mysterious genus of creatures named Prototaxites grew large trunks up to 3 feet (1 meter) wide and 26 feet (8 meters) in height. Scientists have long debated whether these were some kind of weird ancient trees, but a 2007 study concluded they were fungi, not plants.

"A 6-meter fungus would be odd enough in the modern world, but at least we are used to trees quite a bit bigger," study author and paleobotanist C. Kevin Boyce told New Scientist in 2007. "Plants at that time were a few feet tall, invertebrate animals were small, and there were no terrestrial vertebrates. This fossil would have been all the more striking in such a diminutive landscape."

Earth is 4.5 billion years old, and plants may have colonized land as recently as 470 million years ago, most likely mosses and liverworts without deep roots. Vascular plants followed about 420 million years ago, but even for tens of millions of years after that, no plants grew more than about 3 feet (1 meter) off the ground.