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A Rainbow World for Dinos

Posted by | May 4, 2010

Children have always drawn and colored dinosaurs in full, living color. Vibrant oranges and yellows have competed with blues and greens. Now scientists are starting to catch up with what kids have always intuited about the dinosaurs of the Mesozoic Era.

For generations we geologists drew dinos in black and white. Partly, I suspect, that was our habit because our books were printed that way. And just for that simple reason, we may have started to think about Earth’s ancient past in gray terms. I know I did. Fossils are drab, and when all the drawings of fossils you make or see are black and white, it’s easy to start sliding into the assumption that the world of millions of years ago was much less colorful than ours.

When the printing revolution came that transformed our books into color (imagine!), dinos started to be represented as ever so slightly more colorful. Some of them graduated to earthy colors around that point, so that dun colored dinos wandered through richly green plants or waded into blue waters. It wasn’t much for the dinos, making them all look like elephants, but at least their world was more interesting.

Children, thank goodness, were not satisfied with dun. They continued to draw dinosaurs in rich colors. And there’s now some pretty clear evidence kids have been right all along. Dinos – at least some of them – were far from drab. Here’s the story.

In 1996 a small dinosaur fossil, from an animal the size of a mid-sized dog or a turkey, was unearthed in northeast China. It was dated as about 125 million years old.  The fossil made headlines because it was the first dinosaur fossil reported to have feathers. If you ask some eight year olds you know, they’ll tell you this dino is known as Sinosauropteryx. It was a carnivore, judging from its teeth. Its hind legs were big, its front legs little, and it had a big tail, making it a little “road runner” of the Mesozoic.

But how can anybody tell that Sinosauropteryx’s body parts – even its feathers – had color?

The cooperative nature of research science comes to the fore at this point. Just a few years ago, a graduate student at Yale had found some microscopic, similar-looking structures in the ink of a modern squid and those of a squid fossil. Under a microscope, Jakob Vinther could see that tiny spheres in the living squid’s ink looked the same as the ink sack in the fossil squid. The tiny spheres are called melanosomes.

We know that melanosomes create colors in bird feathers. The next step was to look at some feathers from fossil birds – where the grad student and those working with him found melanosomes that look very similar to those in living birds.

Meanwhile, other parts of the greater work were coming together. More and more discoveries of feathery bird-dinosaurs were coming out of the fossil beds of China, which were opened to international investigation for the first time. One of the discoveries was no bigger than a rat but covered in complex feathers. The connections between feathers, dinos, and birds were all becoming clearer and less controversial.

Recently, microscopic analysis of the melanosome in that original discovery – Sinosauropteryx – have persuaded many scientists that the little dinosaur was a cute, two-colored fellow. Much of his back was russet brown. But, get this: his tail was chestnut with white stripes.

But I don’t find the discovery of color in dinosaurs nearly as interesting as how long scientists were willing to present dinosaurs as drab in the extreme. It’s true we didn’t know how to color them in the old days, but children, I think, did better at realizing that we needed to keep our minds open to a great variety of possibilities.

Some dinosaurs, at least, were likely as strongly colored as birds – and for the same reasons. There are advantages when it comes to strutting-your-stuff for the opposite sex if your plumage is truly eye-catching.