First Birds Valued Fashion Over Flight
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.
Archaeopteryx, the iconic early bird that lived around 150 million years ago, sported feathered “trousers” on its hind limbs as well as other decorative feathers, and researchers now believe at least some non-avian dinosaur and bird feathers evolved for flashy display before they were later recruited for flight.
That's the conclusion of a new study, published in the journal Nature, which describes a remarkable new specimen of Archaeopteryx that includes extensive feather preservation.
“The excellent preservation of the feathers in the new specimen helps to clarify many contentious issues,” senior author Oliver Rauhut of Ludwig-Maximilians University Munich told Discovery News. “The specimen not only shows the wing and tail feathers in great detail, but also body plumage and feathers along the hind limbs…(which are) similar to the feather ‘trousers’ found in many modern birds of prey.”
The researchers determined that quill-like feathers covered Archaeopteryx’s entire body up to its head. Its hind limb feathers were symmetrical, indicating they didn't help with flight.
Its tail feathers were extremely long -- more than 60 percent of the length of its bony tail -- with some being asymmetrical and therefore useful in flight. Its wing feathers were also suitable for flight, and appear to have been just as strong as those seen in modern flying birds.
“There are a number of indications that Archaeopteryx was capable of aerial locomotion, but just how well it could fly remains debated,” Rauhut said, adding that the jury is still out as to whether Archaeopteryx was a non-avian dinosaur or a bird. That’s because the transition from one to the other happened gradually.
Current evidence does, however, suggest that Archaeopteryx was a representative of the main evolutionary lineage going toward birds. The evidence also suggests that Archaeopteryx and its dinosaur predecessors were colorful and flashy.
Rauhut shared that “it is very likely that dinosaurs could see colors, and many animals that have this capability tend to be colorful.” Prior studies support this theory.
He and his team suspect that, like modern birds, the colorful feathers likely were used in displays, such as for mating.
It appears that proto-feathers originally evolved for regulating body temperature. The quill-like contour feathers, on the other hand, could have first evolved for show.
“Once present, these feathers could then be adapted for many other functions, such as balance during fast running, protecting and shading the eggs during breeding, and flight,” Rauhut said.
“This is a fine and important piece of work on a great new specimen,” said Mark Norell, division chair and curator-in-charge of the American Museum of Natural History’s Division of Paleontology. “It clearly shows that the evolution of hind limb feathers is very complex and the evolution of feathers as a whole is de-coupled from flight.”
Lawrence Witmer, a professor of anatomy and paleontology at Ohio University, also believes that the new specimen “is a really important find.”
Witmer added, “When you combine the new information from Archaeopteryx with what we see in other bird-like dinosaurs and dinosaur-like birds, the picture that emerges is that maybe (quilled) feathers evolved more as ornaments for display and were later co-opted by evolution for flight … maybe multiple times. I think the authors make a good case. The display argument is very compelling.”