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 fossilized tooth dredged from the bottom of the English Channel near Dorset, England, belonged to a formidable Jurassic marine predator and is the largest known tooth of its kind found in the U.K., according to a new study.
The 2.36-inch-long tooth has a broken tip, and would have been even bigger when new, suggests the paper, published in the journal Historical Biology.
The study determined that the tooth is 152 million years old and belonged to a prehistoric relative of modern crocodiles known as Dakosaurus maximus.
"That (Dakosaurus) had 2.36 inch (6 centimeter) or longer teeth for an animal only 4.5 meters (about 15 feet) long is remarkable," lead author Mark Young told Discovery News.
"The teeth were serrated, robust and contacted one another, making slicing much easier," added Young, a paleontologist at the University of Edinburgh’s School of Biological Sciences. "This animal would have had a fearsome bite for its size."
During the marine predator’s lifetime, a shallow sea covered what is now Europe, turning the landmasses into an archipelago. Archaeopteryx, believed to have been the world’s first bird, lived in Europe during this time, as did some dwarf non-avian dinosaurs, such as Europasaurus. But the real predator action was found in the water.
Young said that Dakosaurus maximus, which belonged to a family of croc predecessors known as metriorhynchids, was puny in comparison to the gigantic marine reptile Pliosaurus. The skull alone of Pliosaurus measured about 6.6 feet long, and some estimates hold that the entire body of this monster predator measured 49 feet long.
Yet another marine predator at the time was Plesiosuchus manselii, which was larger than today’s great white sharks. Dakosaurus maximus, however, was particularly abundant, living in shallow lagoons, coastal environments and deep-sea regions. In the lagoonal environments, which lacked the other large animals, it seems to have been the top predator.
"The shallow seas of the late Jurassic would have been an exceptionally dangerous place to swim," Young said.
Artistic rendition of Mark Young
Fast forward 152 million years, and the D. maximus tooth was found in a collection of material that was dredged from the sea floor near Chesil Beach, Dorset. That’s unusual, because most fossilized teeth from prehistoric marine predators are discovered during excavations, or are found on the shore by experts or lucky individuals with a good eye.
The tooth wound up at an online auction, where a savvy fossil collector purchased it. Lorna Steel, a curator at the Natural History Museum in London, then received a nice surprise.
"I was sent a photo of the tooth by the UK fossil collector," Steel told Discovery News, "asking what did I think this tooth was, so I said, 'Dakosaurus,' and forwarded it to Mark for his opinion. Some of what he said is unrepeatable here, but the collector then offered to sell it to the museum for the price he paid online. We are very grateful to him for his generosity."
Dakosaurus was unlike anything alive today, and what is now Europe was certainly a very different place during the marine creature's lifetime.
"At a time when Archaeopteryx was flying around Germany and Diplodocus (a huge dinosaur) walked the plains of America, Earth’s seas were busy with the giant pliosaurs dominating the food chains," Steel said.
As for Dakosaurus and its kin, she said, "With front limbs modified into flippers and a shark-like tail fin, metriorhynchids were so weird and different from living crocodiles today, it is hard to properly compare them."
Dakosaurus, which sported a bullet-shaped snout, has been nicknamed “Sucker Croc.”
The researchers explained that it could suck in large fish and swallow them whole, in addition to biting off chunks of flesh from larger prey with its impressively big teeth.