1 Dinosaurs Jurassic Microraptor Feathers Were Black with Iridescent Sheen Sat Oct 11, 2014 9:54 pm
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An artist's illustration of Microraptor with iridescent plumage. Image: Jason Brougham/University of Texas
A team of American and Chinese researchers has revealed the color and detailed feather pattern of Microraptor, a pigeon-sized, four-winged dinosaur that lived about 130 million years ago. The non-avian dinosaur’s fossilized plumage, which had hues of black and blue like a crow, is the earliest record of iridescent feather color. The findings, which suggest the importance of display in the early evolution of feathers, will be published in the March 9 edition of the journal Science.
“This study gives us an unprecedented glimpse at what this animal looked like when it was alive,” said Mark Norell, one of the paper’s authors and chair of the American Museum of Natural History’s Division of Paleontology. “There’s been a lot of speculation about how the feathers of Microraptor were oriented and whether they formed airfoils for flight or whether they had to do with sexual display. So while we’ve nailed down what color this animal was, even more importantly, we’ve determined that Microraptor, like many modern birds, most likely used its ornate feathering to give visual social signals.”
Although its anatomy is very similar to birds, Microraptor is considered a non-avian dinosaur and is placed in the group of dinosaurs called dromaeosaurs that includes Velociraptor. The fossilized specimen used in this study comes from rocks in Northeastern China that are about 130 million years old.
A close-up view of the well-preserved feather imprints on the Microraptor fossil. Image: AMNH/M. Ellison
The feather color displayed by many modern birds is produced partially by arrays of pigment-bearing organelles called melanosomes, about a hundred of which can fit across a human hair. Generally found in a round or cigar-like shape, a melanosome’s structure is constant for a given color. With the imaging power of scanning electron microscopes, paleontologists recently started analyzing the shape of melanosomes in well-preserved fossilized feather imprints. By comparing these patterns to those in living birds, scientists can infer the color of dinosaurs that lived many millions of years ago. Iridescence arises when the melanosomes are organized in stacked layers.
“Modern birds use their feathers for many different things, ranging from flight to thermoregulation to mate-attracting displays,” said Matt Shawkey, a co-author and associate professor of biology at the University of Akron. “Iridescence is widespread in modern birds and is frequently used in displays. Our evidence that Microraptor was largely iridescent thus suggests that feathers were important for display even relatively early in their evolution.”
In this study, the researchers compared melanosome shape and density from a Microraptor fossil at the Beijing Museum of Natural History to a database of melanosomes from a variety of modern birds. Statistical analysis of the data predicts that Microraptor was completely black with a glossy, weakly iridescent blue sheen.
The researchers also made predictions about the purpose of the dinosaur’s tail. Once thought to be a broad, teardrop-shaped surface meant to help with flight, Microraptor’s tail fan is actually much narrower with two elongate feathers. The researchers think that the tail feather was ornamental and likely evolved for courtship and other social interactions, not for aerodynamics.
A reconstruction of Microraptor based on digital overlays of nine fossilized specimens. Image: AMNH/M. Ellison
These findings also contradict previous interpretations that Microraptor was a nocturnal animal because dark glossy plumage is not a trait found in modern nighttime birds.
The fossilized Microraptor specimen from the Beijing Museum of Natural History. Image: AMNH/M. Ellison
Other authors on the paper include Qingjin Meng, and Quanguo Li, of the Beijing Museum of Natural History; Liliana D’Alba of the University of Akron; Mick Ellison and Rui Pei of the American Museum of Natural History; and Jakob Vinther of The University of Texas at Austin and Yale University.
Source: American Museum of Natural History
Images: Jason Brougham/University of Texas; AMNH/M. Ellison]