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Iconic Sinosauropteryx dinosaur had bandit mask, lived in open terrain

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IMAGE: This figure shows the best-preserved fossil specimen of Sinosauropteryx from the Early Cretaceous Jehol Biota of China and an interpretive drawing of the bones, stomach contents, and darkly pigmented feathers.... view more 

Credit: Photograph by Jakob Vinther, interpretive drawing by Fiann Smithwick.

While fossils have allowed researchers to reconstruct much about dinosaurs' many impressive forms, it wasn't until more recently that scientists realized they could discern from preserved skin and feathers many details of dinosaurs' color patterns, too. Now researchers reporting in the journal Current Biology on October 26 who've carefully examined three specimens of the iconic Sinosauropteryx dinosaur from China have confirmed that the small dinosaur had a striped tail. It also had a "bandit mask" (think: raccoon).

"The bandit mask was really amazing to discover," says Fiann Smithwick at the University of Bristol, UK. "It's a pattern seen in numerous living animals today."

Sinosauropteryx was also countershaded, meaning that its body was darker on top and lighter underneath. The particular way it was countershaded further suggests that Sinosauropteryx lived in more open habitats, not in the dense forest, the researchers say.

To explore the color pattern of this dinosaur species, Smithwick, along with Jakob Vinther and colleagues, carefully examined the remnants of pigmented feathers from the best-preserved specimens available. By making comparisons among three specimens, they were able to confidently reconstruct the unique way that these dinosaurs looked.

Once the researchers reconstructed the color pattern, they created 3D models of the dinosaur and photographed them under different lighting conditions to see where their coloration would have hidden them best from potential predators. Their images show that Sinosauropteryx must have spent lots of time out in direct sunlight, not in the shade.

The findings are especially interesting in light of an earlier reconstruction by Vinther's team of the color patterns of another dinosaur called Psittacosaurus. Those studies showed that Psittacosaurus was also countershaded, but in a manner suggesting that it lived in the forest. The distinction between species suggests that the environment around China's prehistoric Jehol lakes, where these dinosaurs lived, was unexpectedly diverse, hosting dinosaurs adapted to life in different environments.

"We have shown how a greater understanding of ancient environments can come from better understanding of the paleoecology of extinct animals through paleocolor reconstructions," Vinther says. "Both meat- and plant-eating dinosaurs had excellent vision; both needed to stay camouflaged."

The findings also show that, in some ways, not much has changed in the last 130 million years. Dinosaurs depended on the same camouflage patterns that animals rely on today. "The same rules applied and the same solutions evolved," Smithwick says.

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The authors were funded by the Natural Environment Research Council.

Current Biology, Smithwick et al.: "Countershading and Stripes in the Theropod Dinosaur Sinosauropteryx Reveal Heterogeneous Habitats in the Early Cretaceous Jehol Biota" http://www.cell.com/current-biology/fulltext/S0960-9822(17)31197

Current Biology (@CurrentBiology), published by Cell Press, is a bimonthly journal that features papers across all areas of biology. Current Biology strives to foster communication across fields of biology, both by publishing important findings of general interest and through highly accessible front matter for non-specialists. Visit: http://www.cell.com/current-biology. To receive Cell Press media alerts, contact press@cell.com.

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