All right, that isn't strictly true: birds are certainly the closest living relatives of dinosaurs (and are in fact dinosaurs themselves, by any reasonable measure), but chickens are no closer to T. rex than are swans, ostriches, or toucans. They're also no more distantly related than any of those, though -- and isn't that remarkable? Goofy, awkward, halfway-flightless domesticated featherbags have as much claim to the tyrannosaur's legacy as anything else alive.
Evolution does this sort of thing all the time, altering species in directions quite different from any human notion of "progress." The plant kingdom has hundreds of examples, and none quite as spectacular as the story of Lepidodendron and Isoetes.
|Artist's reconstruction of Lepidodendron.|
This one was as tall as a 9-story building.
300 million years ago, though, the scale trees went extinct. The Carboniferous ended in a planetary cold snap that brought glaciers creeping down from the poles; practically overnight, the rainforests collapsed. Giant lycopsids all but vanished, and tree ferns took their place in the cold new forests.
|A clump of Isoetes tegetiformans with a U.S. penny for scale.|
Not much to look at unless you know what to look for.
These pointy little proto-ferns look about as much like the great Lepidodendron as a chicken resembles Tyrannosaurus. Just like the chicken, though, there are similarities: the structure of their veins, their different male and female spores, and the history traced in their genes. It's all there, if you can find the right way to see. Inside every quillwort is the shadow of an ancient rainforest.
- Heimans, Eli. "Stigmaria [Lepidodendron] reconstruction." Retrieved 20 Feb 2016 from Wikimedia Commons: <https://en.wikipedia.org/wiki/File:Stigmaria_Heimans.jpg>
- US Fish and Wildlife Service. "Isoetes tegetiformans, on granite outcrop in eastern half of Georgia Piedmont." Retrieved 20 Feb 2016 from Wikimedia Commons: <https://commons.wikimedia.org/wiki/File:Isoetes_tegetiformans.jpg>