The order Piciformes includes barbets, toucans, hon-eyguides, and woodpeckers—on the face of it a varied group but, on closer examination, a range of birds with common characteristics. The toucans and barbets are particularly closely related and share a number of physical features: the tooth-edged bills of toucans are rather like elongated, exaggerated forms of the heavy barbet bills, although the smallest barbets, such as tinkerbirds, have much smaller and simpler bills. Toucans and some barbets are essentially fruit-eaters, with a pivotal role in the dispersal of tree seeds in forests. Almost all barbets can excavate nest holes in trees, as do woodpeckers. Of these various families the barbets are the most generalized. Perhaps small species long ago (12-20 million years ago) gave rise to woodpeckers and honeyguides. American toucans and barbets more certainly arose from a common ancestor some 10 million years ago, but the toucans have become more widespread in range (both to the north and the south of the barbets) and habitat choice. It has been said that, in evolutionary terms, the toucans "left the barbets behind" as they developed while the barbets stayed put in the old, tried-and-tested form.
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