A new study looking at the structure of feathers in bird-like dinosaurs has shed light on one of nature's most remarkable inventions – how flight might have evolved.
Academics at the Universities of Bristol, Yale and Calgary have shown that prehistoric birds had a much more primitive version of the wings we see today, with rigid layers of feathers acting as simple airfoils for gliding.
Close examination of the earliest theropod dinosaurs suggests that feathers were initially developed for insulation, arranged in multiple layers to preserve heat, before their shape evolved for display and camouflage.
As evolution changed the configuration of the feathers, their important role in the aerodynamics and mechanics of flight became more apparent.
Natural selection over millions of years ultimately modified dinosaurs' forelimbs into highly-efficient, feathered wings that could rapidly change its span, shape and area – a key innovation that allowed dinosaurs to rule the skies.
This basic wing configuration has remained more or less the same for the past 130 million years, with bird wings having a layer of long, asymmetrical flight feathers with short covert feathers on top. They are able to separate and rotate these flight feathers to gain height, change direction and even hover.
This formation allows birds to move in such a way as to produce both lift and thrust simultaneously – a capability that man, with the help of technology, is still trying to successfully imitate.
The research, published in Current Biology, looked at the dinosaur Anchiornis huxleyi and the Jurassic bird Archaeopteryx lithographica. The latter is 155 million years old and widely considered to be the earliest known bird, presenting a combination of dinosaur and bird characteristics.
Their wings differed from modern day birds in being composed of multiple layers of long feathers, appearing to represent early experiments in the evolution of the wing.
Although individual feathers were relatively weak due to slender feather shafts, the layering of these wing feathers is likely to have produced a strong airfoil.
The inability to separate feathers suggests that taking off and flying at low speeds may have been limited, meaning that wings were primarily used in high-speed gliding or flapping flight.
Jakob Vinther, from the Univ. of Bristol's Schools of Biological and Earth Sciences, says: "We are starting to get an intricate picture of how feathers and birds evolved from within the dinosaurs. We now seem to see that feathers evolved initially for insulation. Later in evolution, more complex vaned or pinnate feathers evolved for display.
"These display feathers turned out to be excellent membranes that could have been utilised for aerial locomotion, which only very late in bird evolution became what we consider flapping flight. This new research is shedding light not just on how birds came to fly, but more specifically on how feathers came to be the way they are today - one of the most amazing and highly specialised structures in nature."
Nicholas Longrich of Yale Univ. added: "By studying fossils carefully, we are now able to start piecing together how the wing evolved. Before, it seemed that we had more or less modern wings from the Jurassic onwards. Now it's clear that early birds were more primitive and represented transitional forms linking birds to dinosaurs. We can see the wing slowly becoming more advanced as we move from Anchiornis, to Archaeopteryx, to later birds."
Monday, November 26, 2012
Monday, March 05, 2012
Oxygen envelops Saturn's icy moon
A Nasa spacecraft has detected oxygen around one of Saturn's icy moons, Dione.
The discovery supports a theory that suggests all of the moons near Saturn and Jupiter might have oxygen around them.
Researchers say that their finding increases the likelihood of finding the ingredients for life on one of the moons orbiting gas giants.
The study has been published in Geophysical Research Letters.
According to co-author Andrew Coates of University College London, Dione has no liquid water and so does not have the conditions to support life. But it is possible that other moons of Jupiter and Saturn do.
"Some of the other moons have liquid oceans and so it is worth looking more closely at them for signs of life," Prof Coates said.
The discovery was made using the Cassini spacecraft, which flew by Dione nearly two years ago. Instruments on board the unmanned probe detected a thin layer of oxygen around the moon, so thin that scientists prefer to call it an "exosphere" rather than an atmosphere.
But the discovery is important because it suggests there is a process at work around the solar system's gas giants, Saturn and Jupiter, in which oxygen is released from their icy satellites.
It seems that highly charged particles from the planets' powerful radiation belts split the water in the ice into hydrogen and oxygen.
Dione's sister moon, Enceladus is thought to harbour a liquid ocean below its icy surface. The same is thought to be true of Europa, Callisto and Ganymede which orbit Jupiter.
Prof Coates is among a group of scientists lobbying the European Space Agency to send an orbiter to explore Jupiter's icy moons - known as the Juice mission.
"These are fascinating places to look for signs of life," he said.
As is Titan, Saturn's largest satellite. Its nitrogen and methane atmosphere is reminiscent of the early Earth, according to Prof Coates.
"It may be an Earth waiting to happen as the outer Solar System warms up," he said.
Nasa is developing a proposal to send a landing craft, or lander, to float on one of the planet's oily lakes.
The discovery supports a theory that suggests all of the moons near Saturn and Jupiter might have oxygen around them.
Researchers say that their finding increases the likelihood of finding the ingredients for life on one of the moons orbiting gas giants.
The study has been published in Geophysical Research Letters.
According to co-author Andrew Coates of University College London, Dione has no liquid water and so does not have the conditions to support life. But it is possible that other moons of Jupiter and Saturn do.
"Some of the other moons have liquid oceans and so it is worth looking more closely at them for signs of life," Prof Coates said.
The discovery was made using the Cassini spacecraft, which flew by Dione nearly two years ago. Instruments on board the unmanned probe detected a thin layer of oxygen around the moon, so thin that scientists prefer to call it an "exosphere" rather than an atmosphere.
But the discovery is important because it suggests there is a process at work around the solar system's gas giants, Saturn and Jupiter, in which oxygen is released from their icy satellites.
It seems that highly charged particles from the planets' powerful radiation belts split the water in the ice into hydrogen and oxygen.
Dione's sister moon, Enceladus is thought to harbour a liquid ocean below its icy surface. The same is thought to be true of Europa, Callisto and Ganymede which orbit Jupiter.
Prof Coates is among a group of scientists lobbying the European Space Agency to send an orbiter to explore Jupiter's icy moons - known as the Juice mission.
"These are fascinating places to look for signs of life," he said.
As is Titan, Saturn's largest satellite. Its nitrogen and methane atmosphere is reminiscent of the early Earth, according to Prof Coates.
"It may be an Earth waiting to happen as the outer Solar System warms up," he said.
Nasa is developing a proposal to send a landing craft, or lander, to float on one of the planet's oily lakes.
Dinosaurs had fleas too _ giant ones, fossils show
Handout photo released by the Nature magazine and obtained on Feburary 28, 2012 shows a female flea from the early Cretaceous period. The giant dinosaurs that roamed the world some 150 million years ago shared the planet with equally daunting parasites: blood-gobbling fleas that were up two centimetres (almost an inch) long. –AFP PHOTO / Nature / D. Huang
WASHINGTON: In the Jurassic era, even the flea was a beast, compared to its minuscule modern descendants. These pesky bloodsuckers were nearly an inch (25 millimeters) long.
New fossils found in China are evidence of the oldest fleas _ from 125 million to 165 million years ago, said Diying Huang of the Nanjing Institute of Geology and Paleontology. Their disproportionately long proboscis, or straw-like mouth, had sharp weapon-like serrated edges that helped them bite and feed from their super-sized hosts, he and other researchers reported Wednesday in the journal Nature.
Scientists figure about eight or more of today’s fleas would fit on the burly back of their ancient ancestor.
‘‘That’s a beast,’’ said study co-author Michael Engel, entomology curator at the Natural History Museum at the University of Kansas. ‘‘It was a big critter. I can’t even imagine coming home and finding my miniature schnauzer with one or more of these things crawling around on it.’’
The ancient female fleas were close to twice the size of the males, researchers found, which fits with modern fleas.
Engel said it is not just the size, however, that was impressive about the nine flea fossils. It was their fearsome beak capable of sticking into and sucking blood from the hides of certain dinosaurs, probably those that had feathers.
These flea beaks ‘‘had almost like a saw running down the side,’’ Engel said. ‘‘This thing was packing a weapon. They were equipped to dig into something.’’
While the ancient fleas were big, they had one disadvantage compared to modern ones: Their legs were not well developed. Evolving over time, fleas went from crawling to jumping, Huang said.
‘‘Luckily for the land animals of the Mesozoic, these big flat fleas lacked the tremendous jumping capacity that our common fleas have,’’ said Joe Hannibal of the Cleveland Museum of Natural History. He was not involved in the study, but he praised it as useful and interesting.
Just finding the fleas was a stroke of luck, Huang said. He first found one in a Chinese fossil market and mentioned it to someone at his hotel. The other guest showed him a photo of another fossilized flea, telling him it was from Daohugou in northeastern China, where there is a famous fossil bed from about 165 million years ago. Huang went there and found fleas preserved in a brownish film of volcanic ash. The grains of rock were so fine you could see antennae and other details of the fleas, he said.
Modern fleas get engorged after they feast on blood, but these did not seem engorged, Engel said.
It should not seem very surprising that large fleas existed more than 100 million years ago. If you go back even farther in time, ancestors of dragonflies and damsel flies had 3-foot-long (1 meter-long) wingspans, Engel said.
WASHINGTON: In the Jurassic era, even the flea was a beast, compared to its minuscule modern descendants. These pesky bloodsuckers were nearly an inch (25 millimeters) long.
New fossils found in China are evidence of the oldest fleas _ from 125 million to 165 million years ago, said Diying Huang of the Nanjing Institute of Geology and Paleontology. Their disproportionately long proboscis, or straw-like mouth, had sharp weapon-like serrated edges that helped them bite and feed from their super-sized hosts, he and other researchers reported Wednesday in the journal Nature.
Scientists figure about eight or more of today’s fleas would fit on the burly back of their ancient ancestor.
‘‘That’s a beast,’’ said study co-author Michael Engel, entomology curator at the Natural History Museum at the University of Kansas. ‘‘It was a big critter. I can’t even imagine coming home and finding my miniature schnauzer with one or more of these things crawling around on it.’’
The ancient female fleas were close to twice the size of the males, researchers found, which fits with modern fleas.
Engel said it is not just the size, however, that was impressive about the nine flea fossils. It was their fearsome beak capable of sticking into and sucking blood from the hides of certain dinosaurs, probably those that had feathers.
These flea beaks ‘‘had almost like a saw running down the side,’’ Engel said. ‘‘This thing was packing a weapon. They were equipped to dig into something.’’
While the ancient fleas were big, they had one disadvantage compared to modern ones: Their legs were not well developed. Evolving over time, fleas went from crawling to jumping, Huang said.
‘‘Luckily for the land animals of the Mesozoic, these big flat fleas lacked the tremendous jumping capacity that our common fleas have,’’ said Joe Hannibal of the Cleveland Museum of Natural History. He was not involved in the study, but he praised it as useful and interesting.
Just finding the fleas was a stroke of luck, Huang said. He first found one in a Chinese fossil market and mentioned it to someone at his hotel. The other guest showed him a photo of another fossilized flea, telling him it was from Daohugou in northeastern China, where there is a famous fossil bed from about 165 million years ago. Huang went there and found fleas preserved in a brownish film of volcanic ash. The grains of rock were so fine you could see antennae and other details of the fleas, he said.
Modern fleas get engorged after they feast on blood, but these did not seem engorged, Engel said.
It should not seem very surprising that large fleas existed more than 100 million years ago. If you go back even farther in time, ancestors of dragonflies and damsel flies had 3-foot-long (1 meter-long) wingspans, Engel said.
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