As paleontologists increasingly unearth evidence of feathers in prehistoric fossils, our conceptions of what dinosaurs looked like when they roamed the earth has gradually evolved.
Instead of the reptilian appearance we all recognize from childhood toys and films like Jurassic Park, many dinosaurs in fact more closely resembled birds, kind of like this recently discovered little guy, Eosinopteryx brevipenna, a flightless theropod dinosaur that roamed China during the Middle/Late Jurassic period.
Archaeopteryx, also known as Urvogel, the German word for "original bird" or "first bird," was first discovered in 1860 and later fossils of this species presented some of the earliest evidence of flight in these prehistoric animals.
An intermediate creature that was not quite dinosaur but not exactly a bird either when it lived 150 million years ago, Archaeopteryx had teeth, a long tail, and wings capable of flight with claws at the end for grabbing prey.
A century after the discovery of Archaeopteryx, paleobiologists increasingly found anatomical connections between birds and dinosaurs. In the 1970s, artists began to portray dinosaurs with feathers based on accumulating evidence.
Megapnosaurus, shown here, was another species with whom researchers began early to identify with feathers. A lightweight animal that could reach up to 10 feet in length and roamed Jurassic Zimbabwe, Megapnosaurus, also known as Syntarsus, traveled in packs and preyed on small reptiles and fish.
Many of the fossils unearthed that provided evidence of feathers had deteriotated over the eons they remained buried. It wasn't until 2010 that researchers identified color pigments in feathers from dinosaurs and early birds.
Sinosauropteryx, illustrated here, was a theropod dinosaur that had "simple bristles -- precursors of feathers -- in alternate orange and white rings down its tail," according to a description of the study's findings.
Given that so many feathered dinosaurs were in fact flightless, the purpose of the feathers has been a subject of debate. Some dinosaurs may have evolved feathers for social signaling; others had plumage to provide insulation.
In the cases of some dinosaurs, such as the two oviraptors, herbivores related to T. rex that lived during the Cretaceous period, researchers believe the feathers were used for mating displays, similar to modern-day peacocks and turkeys.
Jason Brougham/University of Texas
You might be fooled into thinking the animals in this illustration are something between a murder of crows and a band of blue jays. In fact they are Microraptors that lives more than 130 million years ago.
These four-winged, plumed dinosaurs were no larger than modern-day pigeons and sported iridescent tail feathers.
Researchers believe the shimmering plumage was likely used in mating and other social interactions.
Like the diversity among birds today, not all feathered dinosaurs were lightweight, agile animals. A massive tyrannosaur that lived in China until about 65 million years ago, Yutyrannus huali, meaning "beautiful feathered tyrant," grew up to 30 feet long and could weigh more than 3,000 pounds.
This titanic tyrannosaur, as it was described, significantly increases the size range for feathered dinosaurs.
In a stunning find published in the journal Science in 2011, paleontologists uncovered dinosaur feather preserved in amber that dated back some 79 million years ago.
This discovery provided scientists a new window into the evolution of feathers in terms of structure in the evolutionary timeline from dinosaurs to birds. Even shades of color remained well preserved in the amber.
More than 50 million years ago, a giant flightless bird that weighed several hundred pounds lived in the Arctic.
Based on a single toe bone first found in the 1970s, researchers from the Chinese Academy of Sciences in Beijing and the University of Colorado Boulder determined that the bird, named Gastornis, lived in the Arctic Circle on Ellesmere Island.
“People thought there was a larger bird up there but the fossils had never been described,” CU-Boulder’s Jaelyn Eberle, a co-author of a study on the bird that appeared in Scientific Reports, told FoxNews.com of the bone which was in the collection of the Canadian Museum of Nature.
“There are lots of wonderful discoveries we can make in the field,” she said. “But I would say there are a lot of great discoveries that can be made in collections that have been hanging around for a while but, for whatever reason, hadn’t been described. We knew there were birds but nothing had been described until this paper.”
Eberle and the lead author on the study, Thomas Stidham, then compared the bone to those of similar bird fossils found in other parts of the world. They concluded it may be of the same genus as giant birds found in mid-latitude locations.
“Gastornis has been known from mid-latitudes for a long time, from Wyoming, Colorado, Europe. What we were able to do was compare that fossil from the Arctic to all of these mid-latitude specimens,” she said. “I think what is interesting is that the toe is virtually identifical to specimens from Wyoming. The difference is they are 4,000 kilometers (2,485 miles) apart. That is kind of strange.”
Coming upon this bird would have been a terrifying sight and researchers initially believed it was a fearsome carnivore. It would have stood 6 feet tall and been about the size of an adult male with a head about the size of a horse’s.
But more recently, other researchers had found that it was a vegan, using its huge beak to tear at foliage, nuts, seeds and hard fruit. And unlike the harsh conditions of Ellesmere Island today where temperatures can drop to minus 40 degrees in winter, the bird’s environment about 53 million years ago would have been similar to cypress swamps in the southeast, Eberle said.
“It was still formidable but it was the plants that had to be fearful,” Eberle said.
Fossil evidence indicates the island, which is adjacent to Greenland, hosted turtles, alligators, primates, tapirs and even large hippo-like and rhino-like mammals.
And unlike modern day ducks and geese that migrate through the Arctic, Eberle said Gastornis was most likely a year-around resident. It would have had enough to plant material eat, she said, and probably wouldn’t had the energy to migrate elsewhere.
“We would hyphosize that a large bird, just like large mammals up there, could overwinter in the Arctic,” she said. “Because this is a land dwelling bird, I think they were permanent residents. Part of it is because – this is the same argument we use for the mammmals up there - it’s energetically expensive for an animal that walks on land to travel from Ellesmere Island down the tree line each year.”
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