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Photo: Regan Dunn. Breadcrumb Home. Piecing together Patagonia's ancient vegetation.
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See All Recent Updates. Burke paleontologists investigate mass extinctions in Zambia. Get an Inside Look. Major changes to the vegetation have occurred since the settlement of Iceland. Various ongoing changes to the vegetation in modern times are a result of human activity. The Icelandic wilderness is characterised by its large, bare open areas.
Only a fourth of the island is vegetated. Lowland areas tend to have relatively continuous vegetation cover. At a height of — m above sea level, vegetation becomes visibly more sparse. Land above m above sea level is mostly non-vegetated.
Icelandic vegetation is characterised by low-growing plant species and a relatively small number of wild vascular plants. We have land plants to thank for the oxygen we breathe.
And now we have a better idea of when they took to land in the first place. While the oldest known fossils of land plants are million years old, researchers have now determined that pond scum first made landfall almost million years earlier. For decades biologists have been trying to come up with a reliable birth date for land plants.
Lacking backbones and hard shells, plants leave relatively little behind in the fossil record, so researchers suspect even the oldest plant fossils don't represent the first flora. Some scientists have tried to use plant genetic data as "molecular clocks"—knowing a typical mutation rate, they can estimate how long ago various species split based upon their differences in DNA—to figure out their evolutionary history. But they have been unable to sort out the lowest, or earliest, branches of the plant family tree.
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At that base, vascular plants—which include the trees, crops, and flowers we are most familiar with—came along sometime after liverworts, hornworts, and mosses. Yet the order in which those three other groups appeared has been a mystery and has stymied molecular clock studies. Philip Donoghue thought that if he brought enough computer power to bear on this problem, he could solve this mystery. Donoghue, a paleobiologist at the University of Bristol in the United Kingdom, and his colleagues started with previously collected genetic data on more than plant and algal species.