Sept. 15, 2011 --
A stunning array of prehistoric feathers, including dinosaur protofeathers, has been discovered in Late Cretaceous amber from Canada. The 78 to 79-million-year-old amber preserved the feathers in vivid detail, including some of their diverse colors. The collection, published in this week's Science, is among the first to reveal all major evolutionary stages of feather development in non-avian dinosaurs and birds. In this slide, an isolated barb from a vaned feather is visible trapped within a tangled mass of spider's web.
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"These specimens were most likely blown into the tacky resin, or were plucked from an animal as it brushed against resin on a tree trunk," lead author Ryan McKellar told Discovery News. "The fact that we have found some specimens trapped within spider webs in the amber would suggest that wind played an important role in bringing the feathers into contact with the resin," added McKellar, a postdoctoral fellow at the University of Alberta's Department of Earth and Atmospheric Sciences. The feather filaments shown here are similar to protofeathers that have been associated with some dinosaur skeletons.
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McKellar and his team made the discovery after screening over 4,000 amber samples from Grassy Lake, Alberta. The amber, collected by the Leuck family, is now housed at the Royal Tyrrell Museum. The researchers ruled out that the inclusions were mammal hairs, plant or fungal remains based on their structure. Some dinosaur fossils retain skin impressions, so the scientists could match dinosaur protofeathers (hair-like projections) to some of the objects within the amber. Here, a feather is visible near a plant bug. The high number of coils in the this feather suggests it could have come from a water-diving bird.
The translucent tree resin provides a window into feather evolution, from non-avian dinosaurs to birds. "Part of what makes this particular set of feathers interesting is that we find the very simple Stage I and II feathers alongside advanced feathers that are very similar to those of modern birds, Stages IV and V," McKellar said. The researchers aren't yet certain why feathers first evolved, but the density of the protofeathers suggests that they helped dinosaurs with regulating temperature. Dinosaurs such as Troodon or Deinonychus may have produced the feathers. The cork-screw shaped structures in this slide are the tightly coiled bases of feather barbules.
As feathers continued to change, they developed tufts, barbs, branching features, little hooks, and more. Some of the most advanced feathers in the collection are comparable to those of modern grebes. They appear to help diving, indicating that some of the prehistoric birds were divers. McKellar suspects the marine birds might have been Hesperornithiformes, a specialized flightless diving bird from the Dinosaur Era. This is a white belly feather of a modern grebe, showing coiled bases comparable to those seen in the Cretaceous specimen.
Some of the feathers appear transparent now, but would have been white in life. A range of colors for the feathers is evident, though, with grays, reds and various shades of brown preserved. This, and prior research, suggests that non-avian dinosaurs and prehistoric birds could be quite flashy. The pigment within this fossilized feather suggests it would have originally been medium- or dark-brown in color.
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In an accompanying "Perspectives" article in Science, Mark Norell points out that the dinosaur Sinosauropteryx is thought to have had a reddish banded tail, while Anchiornis likely possessed a striking black body, banded wings and a reddish head comb. Norell, chair and curator of the American Museum of Natural History's Division of Paleontology, told Discovery News that the newly discovered feathers are "very exciting." Here, a feather barb within Late Cretaceous Canadian amber shows some indication of original coloration.
Some dino aficionados have wondered if DNA could be extracted from the feathers. "Almost anything is possible," Norell said, quickly adding that most DNA-extraction studies have been conducted on much younger amber, dating to around 20-30 million years ago, and even those led to questionable results. "Maybe bits and pieces could be identified, but not the whole genome." Shown are 16 clumped feathers in Late Cretaceous amber.
People with amber objects, such as jewelry, also probably don't have prehistoric feather inclusions, since such items are extremely rare and dealers isolate the best pieces. Nevertheless, McKellar said, "There is some hope that you could have small feather fragments that have been overlooked." An unpigmented feather and a mite in Canadian Late Cretaceous amber.
A community of lizards from the Caribbean, preserved for 20 million years in amber, have been found to be identical to their modern cousins, say researchers.
This suggests the different niches inhabited by the lizards have - incredibly - changed little over the past 20 million-year, report the team, in this week's Proceedings of the National Academy of Sciences.
"These fossils were really surprising because of how much detail they contained, allowing us to see how these lizards would have looked in real life," says the study's lead author Dr Emma Sherratt of the University of New England in Australia.
Sherratt says amber fossils are usually just a hollow impression, but the new fossils of anolis lizards from the island of Hispaniola, provide phenomenal detail - including the colour of the lizard, what it was last doing, and whether its eyes were open or shut.
"Most of ours had full skeletons, and details of the skin were impressed on the amber, providing very detailed images of tiny scales on the body and on the sticky toe pads," she adds.
"You could have taken a lizard today, embedded it resin and it would have looked like one of these creatures. That's how realistic and modern they look."
Another impressive aspect to the study is the large number of amber fossils analysed.
While previous research has mostly looked at individual specimens, this study involved 38 lizards fossils from various locations on Hispaniola.
Obtain from museums and private collections - one was even a pendant in a necklace - the community of fossils represent the largest group of vertebrates encased in amber.
"Nothing like this has ever been described before," says Sherratt.
There are over 400 species of anolis lizards spread across the islands of the Caribbean, with each species adapting to a specific ecological niche.
Kevin de Queiroz
Earlier DNA studies indicated anolis lizards began colonising the Caribbean about 40 million years ago, quickly diversifying into different niches such as the forest canopy, tree branches, main trucks, leaf litter on the forest floor, or grasslands.
As different groups began occupying different niches, their body shapes, leg length, and the little scales on their toe pads that help them climb like geckos, changed accordingly to suit each niche.
Using x-ray microcomputer tomography to produce three dimensional reconstructions of the fossils inside their amber cocoons, the researchers showed that the diversity of lizards that resulted 20 million years ago is the same seen today.
"Given we see the same range of morphological features this means the community of lizards has remained unchanged all this time," says Sherratt.
Sherratt says it is "very striking" that the lizards don't seem to have changed at all during this long period, during, over which all the main animal types evolved.
"Evidence of anolis lizards living unchanged in different niches for 20 million years, indicates these niches have been stable for that period of time," she says.
"That's quite surprising because these lizards have gone to other islands and over to the Florida mainland where they seem to evolve very rapidly. So it's not that they don't have the propensity to change, it's just that the structure of the environment has been stable enough that they haven't needed to change in 20 million years."
Available evidence suggests that ecological communities change rapidly over the short term, says Sherratt.
However, she says, the findings are among the first to look at long term stability of ecological communities, and show that niches and the communities they support can remain stable over millions of years.