Welcome Guest [Log In] [Register]
Welcome to Carnivora. We hope you enjoy your visit.


You're currently viewing our forum as a guest. This means you are limited to certain areas of the board and there are some features you can't use. If you join our community, you'll be able to access member-only sections, and use many member-only features such as customizing your profile and voting in polls. Registration is simple, fast, and completely free.


Join our community!


If you're already a member please log in to your account to access all of our features:

Username:   Password:
Add Reply
Archaeopteryx lithographica
Topic Started: Jan 8 2012, 02:01 PM (12,868 Views)
Taipan
Member Avatar
Administrator

Archaeopteryx lithographica

Posted Image

Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Archaeopterygiformes
Family: Archaeopterygidae
Genus: Archaeopteryx
Species: Archaeopteryx lithographica

Archaeopteryx, from the late Jurassic Period (Kimmeridgian stage, 155-150 million years ago) of what is now Germany, is the earliest and most primitive known avian. Archaeopteryx was similar in size and shape to a magpie, with broad, rounded wings and a long tail, and reached up to 0.5 meters (1.6 feet) in length. Its feathers resembled those of modern birds but Archaeopteryx was rather different from any bird known today, in that it had jaws lined with sharp teeth, three 'fingers' ending in curved claws and a long bony tail. In 1862, the description of the first intact specimen of Archaeopteryx, just two years after Charles Darwin published The Origin of Species, set off a firestorm of debate about evolution and the role of transitional fossils that endures to this day.

Archaeopteryx and the origins of birds

In the 1970s, John Ostrom argued that the birds evolved from theropod dinosaurs (see Dinosaur-bird connection). Archaeopteryx provides a critical piece of this argument, as it preserves a number of avian features (a wishbone, flight feathers, wings, a partially reversed first toe) and a number of dinosaur and theropod features (for instance, a long ascending process of the astragalus, interdental plates, an obturator process of the ischium, and long chevrons in the tail). In particular, Ostrom found that Archaeopteryx was remarkably similar to the theropod family Dromaeosauridae. Further research on dinosaurs from the Gobi Desert and China has since provided more evidence of a link between Archaeopteryx and the dinosaurs, such as Chinese feathered dinosaurs.

Archaeopteryx is probably close to the ancestry of modern birds - it shows most of the features one would expect in an ancestral bird - but it may not be the direct ancestor of living birds, and it is arguable how much divergence was already present in the early birds at its time.

Posted Image

Plumage

Archaeopteryx specimens were most notable for their well-developed remiges (flight feathers). These are markedly asymmetrical and show the structure of flight feathers of modern birds, with vanes given stability by a barb-barbule-barbicel arrangement. The tail feathers are less asymmetrical, again in line with the situation in modern birds, and also have firm vanes. The thumb did not bear a separately movable tuft of stiff feathers (alula) yet.

Body plumage is less well documented, and only properly researched in the well-preserved Berlin specimen. Thus, as more than one species seems to be involved, the following does not necessarily hold true for all of them. In the Berlin specimen, there are "trousers" of well-developed feathers on the legs; some of these feathers seem to have a basic contour feather structure but are somewhat decomposed (i.e., lack barbicels as in ratites: Christiansen & Bonde, 2004), but at least in part they are firm and thus capable of supporting flight (Longrich, 2006).

There was a patch of pennaceous feathers running along the back which was quite similar to the contour feathers of the body plumage of modern birds in being symmetrical and firm (though not as stiff as the flight-related feathers). Apart from that, the feather traces in the Berlin specimen are limited to a sort of "proto-down" not dissimilar to that found in the dinosaur Sinosauropteryx, being decomposed and fluffy, and possibly even appeared more like fur than like feathers in life (though not in their microscopic structure). These occur on the remainder of the body, as far as such structures are both preserved and not obliterated by preparation, and the lower neck (Christiansen & Bonde, 2004).

On the other hand, there is no indication of feathering on the upper neck and head; while these may conceivably have been nude as in many closely related feathered dinosaurs for which good specimens are available, this may still be an artifact of preservation: it appears that most Archaeopteryx specimens became embedded in anoxic sediment after drifting some time on their back in the sea - the head and neck and the tail are generally bent downwards which suggests that the specimens had just started to rot when they were embedded, with tendons and muscle relaxing so that the characteristic shape of the fossil specimens was achieved. This would mean that the skin was already softened and loose (further evidence is provided by the fact that in some specimens, the flight feathers were starting to detach at the point of embedding in the sediment), and in specimens moving along the ground in shallow water, this would cause the head and upper neck, but not the more firmly attached tail feathers to slough off (Elżanowski, 2002).

It must be mentioned that the feather, the initial specimen described, does not agree too well with the flight-related feathers of Archaeopteryx. It certainly is a remix of a contemporary species, but its size and proportions indicate that it probably belongs to an as of yet undiscovered species of primitive bird or possibly bird-like dinosaur. As the feather was the original type specimen, this has created quite some nomenclatorial confusion.

Posted Image

Flight ability

The flight feathers of Archaeopteryx were highly asymmetrical, as in the wings of modern birds, and the tail feathers are rather broad. This implies that the wings and tail were used for lift generation, but it is unclear whether Archaeopteryx was simply a glider, or capable of flapping flight. The lack of a bony breastbone suggests that Archaeopteryx was not a very strong flier, but flight muscles might have attached to the thick, boomerang-shaped wishbone, the platelike coracoids, or perhaps to a cartilagenous sternum. The sideways orientation of the glenoid (shoulder) joint between scapula, coracoid and humerus - instead of the dorsally angled arrangement found in modern birds - suggests that Archaeopteryx was unable to lift its wings above its back, a requirement for the upstroke found in modern flapping flight. Thus, it seems likely that Archaeopteryx was indeed unable to use flapping flight as modern birds do, but it may well have utilized a downstroke-only flap-assisted gliding technique (Senter, 2006).

Archaeopteryx wings were relatively large, which would have resulted in a low stall speed and reduced turning radius. The short and rounded shape of the wings would have increased drag, but could also have improved Archaeopteryx' ability to fly through cluttered environments such as trees and brush (similar wing shapes are seen in birds which fly through trees and brush, such as crows and pheasants). The presence of "hind wings", asymmetrical flight feathers stemming from the legs similar to those seen in dromaeosaurids such as Microraptor, would also have added to the aerial mobility of Archaeopteryx. The first detailed study of the hind wings by Longrich (2006) suggested that the structures formed up to 12% of the total airfoil. Considering that it is not certain to what extent such feathers capable of supporting flight were present on the legs, this would have reduced stall speed by up to 6% and turning radius by up to 12%, in addition to the stall and turning radius reduction provided by the primary wing and tail feathers.

In 2004, scientists analyzing a detailed CT scan of Archaeopteryx's braincase, concluded that its brain was significantly larger than that of most dinosaurs, indicating that it possessed the brain size necessary for flying. The overall brain anatomy was reconstructed using the scan. The reconstruction showed that the regions associated with vision took up nearly one-third of the brain. Other well-developed areas involved hearing and muscle coordination (Winter, 2004). The skull scan also revealed the structure of the inner ear. The structure more closely resembles that of modern birds than the inner ear of reptiles. These characteristics taken together suggest that Archaeopteryx had the keen sense of hearing, balance, spatial perception and coordination needed to fly (Alnso et al., 2004).

Archaeopteryx continues to play an important part in scientific debates about the origin and evolution of birds. Some scientists see Archaeopteryx as a semi-arboreal climbing animal, following the idea that birds evolved from tree-dwelling gliders (the "trees down" hypothesis for the evolution of flight proposed by O.C. Marsh). Other scientists see Archaeopteryx as running quickly along the ground, supporting the idea that birds evolved flight by running (the "ground up" hypothesis proposed by Samuel Wendell Williston). Still others suggest that Archaeopteryx might have been at home both in the trees and on the ground, like modern crows, and this latter view is what today is considered best-supported by morphological characters. Altogether, it appears that it was a species which was neither particularly specialized for running on the ground, nor for perching. Considering the current knowledge of flight-related morphology, a scenario as outlined by Elżanowski (2002), namely that Archaeopteryx used its wings mainly to escape predators by glides punctuated with shallow downstrokes to reach successively higher perches, and alternatively to cover longer distances by (mainly) gliding down from cliffs or treetops, appears quite reasonable.

Posted Image

Given that it is now well established that several lineages of theropods evolved feathers and flight independently, the question of how precisely the ancestors of Archaeopteryx became able to fly has lost dramatically in importance for the time being. Since it is quite likely that this species belongs to a lineage of birds unrelated to the Neornithes (the Jurassic ancestor of which remains unknown), how exactly flying ability was gained in Archaeopteryx may be a moot point, having little bearing on how this happened in the ancestors of modern birds.

Taxonomy

The relationships of the specimens are problematic. Most specimens have been given their own species at one point or another. The Berlin specimen has been designated as Archaeornis siemensii, the Eichstätt specimen as Jurapteryx recurva, the Munich specimen as Archaeopteryx bavarica and the Solnhofen specimen was designated as Wellnhoferia grandis.

Recently, it has been argued that all the specimens belong to the same species (New Scientist, 17 April 2004, p.17). However, significant differences exist among the specimens. In particular, the Munich, Eichstätt, Solnhofen and Thermopolis specimens differ from the London, Berlin, and Haarlem specimens in being smaller or much larger, having different finger proportions, having more slender snouts, lined with forward-pointing teeth and possible presence of a sternum. These differences are as large as or larger than the differences seen today between adults of different bird species. However, it is also possible that these differences could be explained by different ages of the living birds.

Fossils

Over the years, ten body fossil specimens of Archaeopteryx and a feather that may belong to it have been found. All of the fossils come from the limestone deposits near Solnhofen, Germany. [1]

The feather: Discovered in 1860 near Solnhofen, Germany, and described in 1861 by Hermann von Meyer. Currently located at the Humbolt Museum für Naturkunde in Berlin. This is generally referred to Archaeopteryx and was the initial holotype, but whether it actually is a feather of this species or another, as yet undiscovered, proto-bird is unknown. There are some indications it is indeed not from the same animal as most of the skeletons (the "typical" A. lithographica) (Griffiths, 1996).

London Specimen (BMNH 37001): Discovered in 1861 near Langenaltheim, Germany and described in 1863 by Richard Owen as Archaeopteryx macrura, assuming it did not belong to the same species as the feather. Currently located at the British Museum of Natural History in London, it is missing its head. In a subsequent edition of his Origin of Species (chap. 10, pp.335-336), Charles Darwin acclaimed Owen's discovery as linking lizard-like reptiles with modern birds.

Berlin Specimen (HMN 1880): Discovered in 1876 or 1877 on the Blumenberg near Eichstätt, Germany, by Jakob Niemeyer. He exchanged this precious fossil for a cow, with Johann Dörr. It was described in 1884 by Wilhelm Dames. Currently Located at the Humbolt Museum für Naturkunde, it is the best specimen, and the first with a complete head. Once classified as a new species, A. siemensii, but a recent evaluation supports the A. siemensii species definition [Elzanowski, 2002].

Maxberg Specimen (S5): Discovered in 1956 or 1958 near Langenaltheim and described in 1959 by Heller. Currently missing, though it was once exhibited at the Maxberg Museum in Solnhofen. It belonged to Eduard Opitsch, who loaned it to the museum. After his death in 1991, the specimen was discovered to be missing and may have been stolen or sold. It is composed of a torso.

Haarlem Specimen (TM 6428, also known as the Teyler Specimen): Discovered in 1855 near Riedenburg, Germany and described as a Pterodactylus crassipes in 1875 by von Meyer, it was reclassified in 1970 by John Ostrom. Currently located at the Teyler Museum in Haarlem, the Netherlands. It was the very first specimen, despite the classification error.

Eichstätt Specimen (JM 2257): Discovered in 1951 or 1955 near Workerszell, Germany and described by Peter Wellnhofer in 1974. Currently located at the Jura Museum in Eichstätt, Germany. It is the smallest specimen and has the second best head. Possibly a separate genus, Jurapteryx recurva or species A. recurva.

Solnhofen Specimen (BSP 1999): Discovered in the 1960s near Eichstätt, Germany and described in 1988 by Wellnhofer. Currently located at the Bürgermeister-Müller-Museum in Solnhofen. It was originally classified as a Compsognathus by an amateur collector. It is the largest specimen known and may belong to a separate genus and species, Wellnhoferia grandis.

Munich Specimen (S6, formerly known as the Solnhofen-Aktien-Verein Specimen): Discovered in 1991 near Langenaltheim and described in 1993 by Wellnhofer. Currently located at the Paläontologische Museum München in Munich. What was initially believed to be a bony sternum turned out to be part of the coracoid (Wellnhofer & Tischlinger, 2004), but a cartilaginous sternum may have been present. May be a new species, A. bavarica.

Bürgermeister-Müller Specimen: An eighth, fragmentary specimen, was discovered in 1997. It is kept at the Bürgermeister-Müller Museum.
A further fragmentary fossil was found in 2004.

Thermopolis Specimen Discovered in Germany. Long in a private collection, described in 2005 by Mayr, Pohl, and Peters. Donated to the Wyoming Dinosaur Center in Thermopolis, Wyoming, it has the best-preserved head and feet. The "Thermopolis" specimen, was described in the December 2, 2005 Science journal article as "A well-preserved Archaeopteryx specimen with theropod features", shows that the Archaeopteryx lacked a reversed toe—a universal feature of birds—limiting its ability to perch in trees and implying a terrestrial lifestyle. This has been interpreted as evidence of theropod ancestry. The specimen also has a hyperextendible second toe. "Until now, the feature was thought to belong only to the species' close relatives, the deinonychosaurs."

Posted Image





Edited by Taipan, Jul 3 2014, 04:06 PM.
Offline Profile Quote Post Goto Top
 
Taipan
Member Avatar
Administrator

High-tech Imaging Of Inner Ear Sheds Light On Hearing, Behavior Of Oldest Fossil Bird

ScienceDaily (Jan. 14, 2009) — The earliest known bird, the magpie-sized Archaeopteryx, had a similar hearing range to the modern emu, which suggests that the 145 million-year-old creature — despite its reptilian teeth and long tail — was more birdlike than reptilian, according to new research.

Using innovative modern technology, a team of paleontologists and biologists from London, Munich and Ohio have shown for the first time how the length of the inner ear of birds and reptiles can be used to accurately predict their hearing ability and even aspects of their behavior.

"In modern living reptiles and birds we found that the length of the bony canal containing the sensory tissue of the inner ear is strongly related to their hearing ability," said study co-author Paul Barrett, a palaeontologist at London's Natural History Museum. "We were then able to use these results to predict how extinct birds and reptiles may have heard and found that Archaeopteryx had an average hearing range of approximately 2000 Hz. This means it had similar hearing to modern emus, which have some of the most limited hearing ranges of modern birds."

Researchers previously have only been able to estimate how prehistoric animals heard by examining the skulls of damaged fossils and relating brain region size to hearing ability, based on comparisons to the animals' modern relatives. Computed tomography or CT imaging, however, allowed the team to accurately reconstruct the inner ear anatomy of various intact bird and reptile specimens. Fifty-nine species were studied, including turtles, crocodiles, snakes and birds.

"By examining the three dimensional CT scans we were able to see for the first time the real relationship between hearing ability and behavior in extinct reptiles and birds," said Stig Walsh, Natural History Museum palaeontologist and lead author on the study. "The size of the cochlea duct (the bony part of the inner ear housing the hearing organ) in living birds and reptiles accurately predicts the hearing ranges of these animals. This simple measurement can therefore provide a direct means for determining hearing capabilities, and possibly behavior, in their extinct relatives, including Archaeopteryx."

The study, published in the latest issue of the journal Proceedings of the Royal Society B, also adds more information about how bird-like Archaeopteryx was, said Angela Milner, also from the Natural History Museum. "Our previous research has shown that the part of the ear that controls balance was just like that of modern birds, and now we know that Archaeopteryx had bird-like hearing too," she said.

Other team members included Geoff Manley from the Technical University of Munich, who is a leading scientist in the study of hearing in modern animals, and Lawrence Witmer of Ohio University's College of Osteopathic Medicine in Athens, Ohio. Witmer has studied the structure of the brain and inner ear in dozens of species of dinosaurs and modern and extinct birds, including Archaeopteryx.

"This delicate little inner ear has only recently become a player for those of us trying to interpret the past, because it's buried deep within the skull," said Witmer, whose research is funded by the National Science Foundation. "Thanks to CT scanning, we can now get a clear picture of its structure. It's turned out to be a pretty useful organ for deciphering the lives of extinct animals. My previous research has shown that inner ear structure also can tell us about eye movements, head posture, agility, and the relative importance of hearing, and this new study now shows that this sensory Swiss-army knife can tell us about sociality, vocal complexity and maybe even habitat preference."

Animals with a long cochlear duct tended to have the best hearing and vocal ability. Modern living bird species are known to possess relatively longer cochlear ducts than living reptiles. A long cochlear duct is also an indicator of an individual's complex vocal communication, living in groups and even habitat choice. This is true for both mammals and birds.

"Species that form large social groups have more complicated vocal communication, which is understandably influenced by an individual's ability to hear. Species living in a closed environment where visual communication is ineffective often posses more complex vocal abilities, so now we can more accurately predict the habitat types that extinct animals lived in by examining their ability to hear and communicate," Barrett said.

The research received funding from the Natural Environment Research Council and the National Science Foundation.

Posted Image

http://www.sciencedaily.com/releases/2009/01/090113201350.htm
Edited by Taipan, May 22 2014, 01:52 PM.
Offline Profile Quote Post Goto Top
 
Taipan
Member Avatar
Administrator

Archaeopteryx Was Not Very Bird-like: Inside The First Bird, Surprising Signs Of A Dinosaur

ScienceDaily (Oct. 9, 2009) — The raptor-like Archaeopteryx has long been viewed as the archetypal first bird, but new research reveals that it was actually a lot less "bird-like" than scientists had believed.

In fact, the landmark study led by paleobiologist Gregory M. Erickson of The Florida State University has upended the iconic first-known-bird image of Archaeopteryx (from the Greek for "ancient wing"), which lived 150 million years ago during the Late Jurassic period in what is now Germany. Instead, the animal has been recast as more of a feathered dinosaur -- bird on the outside, dinosaur on the inside.

That's because new, microscopic images of the ancient cells and blood vessels inside the bones of the winged, feathered, claw-handed creature show unexpectedly slow growth and maturation that took years, similar to that found in dinosaurs, from which birds evolved. In contrast, living birds grow rapidly and mature in a matter of weeks.

Also groundbreaking is the finding that the rapid bone growth common to all living birds but surprisingly absent from the Archaeopteryx was not necessary for avian dinosaur flight.

The study is published in the Oct. 9, 2009, issue of the journal PLoS ONE. In addition to Erickson, an associate professor in Florida State's Department of Biological Science and a research associate at the American Museum of Natural History, co-authors include Florida State University biologist Brian D. Inouye and other U.S. scientists, as well as researchers from Germany and China.

"Living birds mature very quickly," Erickson said. "That's why we rarely see baby birds among flocks of invariably identical-size pigeons. Slow-growing animals such as Archaeopteryx would look foreign to contemporary bird-watchers."

Erickson said evidence already confirms that birds are, in fact, dinosaurs. "But just how dinosaur-like -- or even bird-like -- was the first bird?" he asked. "Almost nothing had been known of Archaeopteryx biology. There has been debate as to how well it flew, if at all. Some have suggested that early bird physiology may have been very different from living birds, but no one had tested fossils that were close to the base of bird ancestry."

Fossilized remains of Archaeopteryx were found in Germany in 1860, one year after Charles Darwin's "Origin of Species" was published. With its combination of bird-like features, including feathers and a wishbone, and reptilian ones -- teeth, three-fingered hands, a long bony tail -- the skeleton made evolutionary theory more credible. The 1860s evolutionist Thomas Henry Huxley saw the Archaeopteryx as a perfect transition between birds and reptiles. Erickson calls it "the poster child for evolution."

"For our study, which required tremendous collaboration, we set out to determine how Archaeopteryx grew and compare its growth to living birds, closely related non-avian dinosaurs, and other early birds that came after it," Erickson said. "I went to Munich with my colleague Mark Norell from the American Museum of Natural History, and we met with Oliver Rauhut, curator of the Bavarian State Collection for Palaeontology and Geology, which houses a small juvenile Archaeopteryx that is one of 10 specimens discovered to date. From that specimen, we extracted tiny bone chips and then examined them microscopically."

Surprisingly, the bones of the juvenile Archaeopteryx were not the highly vascularized, fast-growing type, as in other avian dinosaurs. Instead, Erickson found lizard-like, dense, nearly avascular bone.

"It led us to ask, 'Did Archaeopteryx grow in a unique way?'" he said.

To explain the strange bone type, the researchers also examined different-size species of dinosaurs that were close relatives of Archaeopteryx, including Deinonychosaurs, the raptors of "Jurassic Park" fame. They then looked to colleagues in China for specimens of two of the earliest birds: Jeholornis prima, a long-tailed creature, and the short-tailed Sapeornis chaochengensi, which had three fingers and teeth.

"In the smallest dinosaur specimens, and in an early bird, we found the same bone type as in the juvenile Archaopteryx specimen," Erickson said.

Next, the research team plugged bone formation rates into the sizes of the Archaeopteryx femora (thigh bones) to predict its rate of growth.

"We learned that the adult would have been raven-sized and taken about 970 days to mature," Erickson said. "Some same-size birds today can do likewise in eight or nine weeks. In contrast, maximal growth rates for Archaeopteryx resemble dinosaur rates, which are three times slower than living birds and four times faster than living reptiles.

"From these findings, we see that the physiological and metabolic transition into true birds occurred millions of years after Archaeopteryx," he said. "But, perhaps equally important, we've shown that avians were able to fly even with dinosaur physiology."

Inouye added, "Our data on dinosaur growth rates and survivorship are bringing modern physiology and population biology to a field that has historically focused more on finding and naming fossil species."

Funding for the study came from the National Science Foundation (NSF); Germany's Deutsche Forschungsgemeinschaft (DFG); and The Major Basic Research Projects of the Ministry of Science and Technology of China.

In addition to Gregory Erickson (first author) and Brian Inouye of Florida State University's Department of Biological Science in Tallahassee, Fla., co-authors of the PLoS ONE paper are Oliver W. M. Rauhut, Bavarian State Collection for Palaeontology and Geology, LMU Munich, Munich, Germany; Zhonghe Zhou, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China; Alan Turner, Department of Anatomical Sciences, Stony Brook University, Stony Brook, N.Y.; Dongyu Hu, Paleontological Institute, Shenyang Normal University, Shenyang, China; and Mark Norell, Division of Paleontology, American Museum of Natural History, New York, N.Y.

Posted Image
This is the slab and counter slab of the Munich Archaeopteryx.

--------------------------------------------------------------------------------

Journal reference:

Erickson et al. Was Dinosaurian Physiology Inherited by Birds? Reconciling Slow Growth in Archaeopteryx. PLoS ONE, 2009; 4 (10): e7390 DOI: 10.1371/journal.pone.0007390

http://www.sciencedaily.com/releases/2009/10/091009090436.htm
Edited by Taipan, May 22 2014, 01:53 PM.
Offline Profile Quote Post Goto Top
 
Taipan
Member Avatar
Administrator

Fossil reveals early bird plumage

Page last updated at 23:46 GMT, Monday, 10 May 2010 0:46 UK
By Pallab Ghosh
Science correspondent, BBC News

Posted Image
Archaeopteryx fossils capture a snapshot of evolution

A new study of a 150-million-year-old fossil of an Archaeopteryx has shown that remnants of its feathers have been preserved.

Archaeopteryx is regarded as a "missing link" that documents a fabulous transition from dinosaur to bird.

The researchers say that it may soon be possible to work out the colours of feathers sported by these creatures.

The new work is published in the journal Proceedings of the National Academy of Sciences (PNAS).

But the authors warn museum curators not to be overzealous in cleaning up fossils for display in case they destroy vital scientific data.

Archaeopteryx is the most iconic of fossils: Many of the specimens beautifully capture this snapshot of evolution - showing the creature's skeleton, feathers and teeth in great detail.

But now a new scanning technique has revealed that one fossil contains fragments of the original feathers - rather than just being an imprint of an animal whose remains had long ago disintegrated into the dust.

The bad news though is that museum curators have inadvertently chipped and scrubbed off a lot more fragments of the creature's feathers and skin fragments as they prepared the fossil for public display to highlight the bones.

But researchers are hopeful they'll be able to study other specimens and obtain more details of the chemistry of the creature's feathers and possibly learn more about their colour.

Dr Roy Wogelius, from University of Manchester, who was among those who made the discovery, is keen to alert curators that the new scanning techniques reveal that many precious fossils contain more than just the remnants of bone.

"One of the things we are very concerned about is that some of the original information has been lost forever," he said.

Posted Image
One fossil contains fragments of the original feathers

"The preparation and curation of (fossils) needs to take account of the fact that there may be very, very small quantities of chemical remains which curators can tend to remove."

The details were obtained by firing intense X-rays at the sample generated by a so-called synchrotron radiation source at the Stanford Linear Accelerator in California, US.

Dr Uwe Bergmann, who led the X-ray scanning experiment at SLAC, said: "People have never used a technique this sensitive on Archaeopteryx before.

"Because the beam is so bright, we were able to see the teeniest chemical traces that nobody thought were there."

Another member of the team, Dr Phil Manning, from Manchester University, believes that the study shows there's now a new way to study long-extinct creatures.

"I wouldn't be surprised if future excavations look more like CSI investigations where people look for clues at a scene of a crime," he said.

In the bones

As well as identifying the feathers the research team also found that the creature's bones have a chemical composition similar to those of birds lving today.

"To me that's quite exciting," said Dr Wogelius. "It establishes a nutrient link between a and modern birds. If you have a pet bird such as a budgie or a paraquet the key nutrients to get right for your pet's health are copper and zinc."

The researchers have learned all they can from this particular specimen. But they hope that their work shows there's more to be learned from fossils and that museum curators should now approach the process of preparing fossils for display with this in mind.

"We've shown that this kind of approach can resolve chemical information that no one has ever seen," according to Dr Wogelius.

"It's an extremely important result for looking at other fossils and it means that there's a lot more richness in chemical detail that in the past has been missed."

http://news.bbc.co.uk/2/hi/science_and_environment/10106530.stm
Offline Profile Quote Post Goto Top
 
Taipan
Member Avatar
Administrator

Prehistoric Birds Were Poor Flyers, Research Shows

ScienceDaily (May 26, 2010) — The evolution of flight took longer than previously thought with the ancestors of modern birds "rubbish" at flying, if they flew at all, according to scientists.

Archaeopteryx, the theropod dinosaur believed to be the earliest bird, was discovered 150 years ago but debates about how flight evolved still persist. The two theories are that flight evolved in running bipeds through a series of short jumps or that Archaeopteryx leapt from tree to tree using its wings as a balancing mechanism.

Dr Robert Nudds at The University of Manchester is carrying out a series of biomechanical investigations to shed light on the subject with his colleague Dr Gareth d**e at University College Dublin.

For their latest paper Dr Nudds and Dr d**e applied a novel biomechanical analysis to the flight feathers of the early birds Archaeopteryx and Confuciusornis to find out if they were strong enough to allow flight.

They found that the dinosaur feathers' much thinner central stem (rachis) must have been solid or they would have broken under the lift forces generated during flight or by gusts of wind. This solid structure is very different to modern birds, whose rachises are broader, hollow straws. If the dinosaurs' feathers had had hollow rachises, they would not have been able to fly at all.

"These are surprising results," says Dr Nudds, whose findings are published in Science.

"I thought the feathers would be strong enough with a hollow rachis to fly but they weren't. Even with a solid rachis, they were not very good. These dinosaurs were rubbish at flying.

"This pushes the origin of flapping flight to after Archaeopteryx and Confuciusornis. It must have come much later."

It is impossible to tell from fossils whether the rachises were solid or hollow. However Dr Nudds, at Manchester's Faculty of Life Sciences, believes the dinosaurs' feathers were solid and therefore they could fly, but very poorly.

"The fossilsof Confuciusornis and Archaeopteryx suggest flight and at this stage it would be a brave person to say they couldn't fly" he says.

"However their feathers must have been very different to modern birds and they were poor fliers. I believe the feathers were originally for insulation or display purposes then they found that by elongating them they had a parachuting surface, then a gliding surface.

"Archaeopteryx and Confuciusornis are still at a very early stage in the evolution of flight."

Dr Nudds' and Dr d**es' work builds on their previous paper, in the journal Evolution, which investigated how the movement of feathered dinosaur forelimbs evolved into flapping flight. Again they found the flight was a consequence of gradual changes in wing shape and movement -- a long, slow evolution.

Dr Nudds adds: "Our analysis also shows that Confuciusornis, which is younger by 25 million years, was worse at flying than Archaeopteryx. This raises the further question of lineage -- did the dinosaur-bird line branch off, giving rise to flying and flightless birds?"

He and Dr d**e plan to analyse other fossilized feathers to find out when flapping flight evolved. However such specimens are rare.

"I don't mind," says Dr Nudds. "It makes it more exciting and all the more intriguing."

Posted Image
Archaeopteryx.

http://www.sciencedaily.com/releases/2010/05/100526100612.htm
Edited by Taipan, May 22 2014, 01:54 PM.
Offline Profile Quote Post Goto Top
 
Taipan
Member Avatar
Administrator

Winged Dinosaur Archaeopteryx Dressed for Flight

ScienceDaily (Jan. 24, 2012) — Since its discovery 150 years ago, scientists have puzzled over whether the winged dinosaur Archaeopteryx represents the missing link in birds' evolution to powered flight. Much of the debate has focused on the iconic creature's wings and the mystery of whether -- and how well -- it could fly.

Some secrets have been revealed by an international team of researchers led by Brown University. Through a novel analytic approach, the researchers have determined that a well-preserved feather on the raven-sized dinosaur's wing was black. The color and parts of cells that would have supplied pigment are evidence the wing feathers were rigid and durable, traits that would have helped Archaeopteryx to fly.

The team also learned from its examination that Archaeopteryx's feather structure is identical to that of living birds, a discovery that shows modern wing feathers had evolved as early as 150 million years ago in the Jurassic period. The study, which appears in Nature Communications, was funded by the National Geographic Society and the U.S. Air Force Office of Scientific Research.

"If Archaeopteryx was flapping or gliding, the presence of melanosomes [pigment-producing parts of a cell] would have given the feathers additional structural support," said Ryan Carney, an evolutionary biologist at Brown and the paper's lead author. "This would have been advantageous during this early evolutionary stage of dinosaur flight."

The Archaeopteryx feather was discovered in a limestone deposit in Germany in 1861, a few years after the publication of Charles Darwin's On the Origin of Species. Paleontologists have long been excited about the fossil and other Archaeopteryx specimens, thinking they place the dinosaur at the base of the bird evolutionary tree. The traits that make Archaeopteryx an evolutionary intermediate between dinosaurs and birds, scientists say, are the combination of reptilian features (teeth, clawed fingers, and a bony tail) and avian features (feathered wings and a wishbone).

The lack of knowledge of Archaeopteryx's feather structure and color bedeviled scientists. Carney, with researchers from Yale University, the University of Akron, and the Carl Zeiss laboratory in Germany, analyzed the feather and discovered that it is a covert, so named because these feathers cover the primary and secondary wing feathers birds use in flight. After two unsuccessful attempts to image the melanosomes, the group tried a more powerful type of scanning electron microscope at Zeiss, where the group located patches of hundreds of the structures still encased in the fossilized feather.

"The third time was the charm, and we finally found the keys to unlocking the feather's original color, hidden in the rock for the past 150 million years," said Carney, a graduate student in the Department of Ecology and Evolutionary Biology, studying with Stephen Gatesy.

Melanosomes had long been known to be present in other fossil feathers, but had been misidentified as bacteria. In 2006, coauthor Jakob Vinther, then a graduate student at Yale, discovered melanin preserved in the ink sac of a fossilized squid. "This made me think that melanin could be fossilized in many other fossils such as feathers," said Vinther, now a postdoctoral researcher at the University of Texas-Austin. "I realized that I had opened a whole new chapter of what we can do to understand the nature of extinct feathered dinosaurs and birds."

The team measured the length and width of the sausage-shaped melanosomes, roughly 1 micron long and 250 nanometers wide. To determine the melanosomes' color, Akron researchers Matthew Shawkey and Liliana D'Alba statistically compared Archaeopteryx's melanosomes with those found in 87 species of living birds, representing four classes: black, gray, brown, and a type found in penguins. "What we found was that the feather was predicted to be black with 95 percent certainty," Carney said.

Next, the team sought to better define the melanosomes' structure. For that, they examined the fossilized barbules -- tiny, rib-like appendages that overlap and interlock like zippers to give a feather rigidity and strength. The barbules and the alignment of melanosomes within them, Carney said, are identical to those found in modern birds.

What the pigment was used for is less clear. The black color of the Archaeopteryx wing feather may have served to regulate body temperature, act as camouflage or be employed for display. But it could have been for flight, too.

"We can't say it's proof that Archaeopteryx was a flier. But what we can say is that in modern bird feathers, these melanosomes provide additional strength and resistance to abrasion from flight, which is why wing feathers and their tips are the most likely areas to be pigmented," Carney said. "With Archaeopteryx, as with birds today, the melanosomes we found would have provided similar structural advantages, regardless of whether the pigmentation initially evolved for another purpose."

Contributing authors include Vinther, Shawkey, D'Alba, and Jörg Ackermann from Carl Zeiss.

Posted Image
Berlin specimen of Archaeopteryx: Paleontologists have long thought that Archaeopteryx fossils, including this one discovered in Germany, placed the dinosaur at the base of the bird evolutionary tree.

Journal Reference:

Ryan M. Carney, Jakob Vinther, Matthew D. Shawkey, Liliana D'Alba, Jörg Ackermann. New evidence on the colour and nature of the isolated Archaeopteryx feather. Nature Communications, 2012; 3: 637 DOI: [url]10.1038/ncomms1642[/url]
Offline Profile Quote Post Goto Top
 
Taipan
Member Avatar
Administrator

Birdlike Dinos Had Tough Time Flying

by LiveScience StaffDate: 21 November 2012 Time: 03:34 PM ET

Posted Image
An Archaeopteryx fossil discovered in Germany

Some of the first birdlike creatures to emerge during the age of the dinosaurs probably couldn't get their heavy wings to take them off the ground and likely opted for gliding over flying, new research shows.

Modern flying birds have a single primary layer of easily separated long feathers covered with short ones — a design that helps them overcome drag when taking flight. A new analysis of the fossils of two of their ancestors shows that the arrangement of feathers for primitive birds was quite different.

The birdlike dinosaurs Anchiornis huxley and Archaeopteryx lithographica had dense overlapping layers of wing feathers that were likely difficult to separate, the researchers found. Instead of lifting off from the ground, these creatures probably climbed trees and used their wings to glide from a height, the scientists said.

What's more, differences in the wing feathers of Archaeopteryx and Anchiornis appear to represent early evolutionary experiments in wing design, according to the researchers. For example, Archaeopteryx had multiple layers of long feathers, while Anchiornis had an abundance of simple feathers that overlap like a penguin's, said study researcher Nicholas R. Longrich, a postdoctoral fellow at Yale.

Longrich's colleague Jakob Vinther, a former Yale doctoral student, now with the University of Bristol in the United Kingdom, said the fossil analyses add to an intricate picture of how feathers and modern birds evolved.

"We now seem to see that feathers evolved initially for insulation," Vinther explained in a statement. "More complex vaned or pinnate feathers evolved for display. These display feathers turned out to be excellent membranes that could have been utilized for aerial locomotion, which only very late in bird evolution became what we consider flapping flight."

The research was detailed today (Nov. 21) online in the journal Current Biology.

http://www.livescience.com/24982-birdlike-dinos-had-tough-time-flying.html
Offline Profile Quote Post Goto Top
 
Taipan
Member Avatar
Administrator

True Color of Dinosaur Feathers Debated

Megan Gannon, News Editor
Date: 28 March 2013 Time: 11:41 AM ET

Posted Image
Artist's illustration of two Microraptor with iridescent plumage.

The discovery of microscopic color-making structures in fossilized feathers has recently made it possible for scientists to picture dinosaurs and ancient birds in their natural hues.

But a group of researchers warns we might not be able to paint a Microraptor shimmery black or give the giant penguin a maroon and gray coat just yet.

To reconstruct the elusive color of feathered dinosaurs, scientists have zeroed in on melanosomes, melanin-loaded organelles typically present in the cells of the skin, hair and feathers whose colors (which range from black to brown to reddish) are each associated with a specific geometry. Though the visible color of melanosomes often degrades over time, their preserved size, shape and arrangement and can give some hints about their original color.

But the melanosomes encased in feather fossils today could have a distorted shape that leads scientists to the wrong conclusion about their true color, according to the new study.

Since scientists don't have hundreds of millions of years to watch how feather fossilization takes place from start to finish, Maria McNamara, of the University of Bristol, and her colleagues simulated a long burial by popping bird feathers into an autoclave, subjecting them to temperatures up to 482 degrees Fahrenheit (250 degrees Celsius) and intense pressure, about 250 times that of the atmosphere. The researchers found that the melanosomes shrank under these harsh conditions.

Some scientists who have studied the color of fossilized feathers say they took this shrinkage into consideration and don't believe revisions are in order.

Ryan Carney, a researcher at Brown University, worked on a study of the feathers of Archaeopteryx, a species once considered to be the earliest bird that lived about 150 million years ago in what is now Bavaria in Germany. Carney and his colleagues, who published their findings last year, concluded that Archaeopteryx had a black plumage based on an electron microscope-view of hundreds of melanosomes found within a fossil.

Carney told LiveScience that although the melanosomes shrink over time, their original shape leaves an imprint in the rock.

"In the Archaeopteryx feather for example, we found that length and width of melanosomes were significantly smaller compared to those of imprints, and the shrinkage was actually quite similar to that of the McNamara et al experiment," Carney wrote in an email. Another researcher, Jakob Vinther, of the University of Bristol, who worked on the Archaeopteryx study — as well as feather-color reconstructions for the giant penguin Inkayacu paracasensis and the Microraptor — echoed Carney's remarks in comments to Nature.

Even so, McNamara said another important finding of her study was that melanosomes survive fossilization even after the disappearance other non-melanin color traces, such as carotenoids, which can create brilliant shades of orange. Yellow, red, green and blue feathers all turned black during the experiments because their non-melanin pigments were destroyed and only the melanosomes survived, McNamara told LiveScience. So finding melanosomes might not necessarily mean the feathers were originally black, brown, or reddish, she added.

"The bottom line is that until we understand how the fossilisation process affects these colour-producing chemicals and structures, and until we know how to look for evidence of these in fossils, there's really no point in attempting to reconstruct colour of feathers based on melanosomes alone," McNamara wrote in an email.

The goal of figuring out the true color of dinosaur feathers goes beyond achieving better paleo-art; colors could offer a rare glimpse into the behavior of long-gone creatures.

As modern animals use their plumage in mating signals, warning signs and camouflage, body color "could yield unique insights into how ancient animals communicated with each other, and how the communication strategies used by modern animals have evolved," McNamara said.

Carney added that color could even give clues about the development of dinosaur flight.

"For example, the melanin in the Archaeopteryx wing feather would not only have provided black coloration, but also increased structural integrity that would have been advantageous during this early evolutionary stage of dinosaur flight," he wrote.

McNamara's results were published Wednesday (March 27) in the journal Biology Letters.

http://www.livescience.com/28262-dinosaur-feather-color-debated.html
Offline Profile Quote Post Goto Top
 
Taipan
Member Avatar
Administrator

Archaeopteryx restored in fossil reshuffle

By Jonathan Amos
Science correspondent, BBC News
29 May 2013 Last updated at 17:12 GMT

Posted Image
Features seen in the bones of Aurornis tell scientists they are looking at the beginning of the bird line

What may be the earliest creature yet discovered on the evolutionary line to birds has been unearthed in China.

The fossil animal, which retains impressions of feathers, is dated to be about 160 million years old.

Scientists have given it the name Aurornis, which means "dawn bird".

The significance of the find, they tell Nature magazine, is that it helps simplify not only our understanding for how birds emerged from dinosaurs but also for how powered flight originated.

Aurornis xui, to give it its full name, is preserved in a shale slab pulled from the famous fossil beds of Liaoning Province.

About 50cm tail to beak, the animal has very primitive skeletal features that put it right at the base of the avialans - the group that includes birds and their close relatives since the divergence from dinosaurs.

Posted Image
How it might have looked: Aurornis would have lived in forested environment

Pascal Godefroit from the Royal Belgian Institute of Natural Sciences is the lead author on the paper that describes Aurornis.

His Nature publication also reports details of an across-the-board re-analysis of how the many bird-like creatures living in Jurassic and Cretaceous times were related to each other.

This was done by comparing the detail in the shape of their bones.

The major consequence of this phylogenetic re-assessment is that it restores one of the most famous fossils ever found to the bird line.

Archaeopteryx, dubbed "the first true bird" when first identified in the 19th Century, was shunted recently into a pool of non-avian but bird-looking dinosaurs as a result of the many exquisite feathered creatures emerging in Liaoning. The skeletal features seen in these new specimens had appeared to make Archaeopteryx less pivotal.

However, this demotion caused some consternation because Archaeopteryx, which lived roughly 150 million years ago, could clearly fly; and by re-classifying the animal it had implied also that powered flight must have evolved at least twice - once on the real line to birds and again in this parallel pool of dinosaurs that merely shared some bird features.

But the re-analysis conducted following the discovery of Aurornis has once again simplified the picture.

Posted Image
The first Archaeopteryx fossils were discovered in the 1860s

"Previous phylogenetic investigations were based on maybe only 200 morphological characteristics. Here, we recognise almost 1,500 characteristics," explained Dr Godefroit.

"So it's a much bigger and more robust analysis, and according to this new investigation Archaeopteryx is again considered an ancestor of birds and the new creature we describe is also a basal bird; and in fact it is even more primitive than Archaeopteryx," he told BBC News.

As well as placing Archaeopteryx at one of the earliest points of divergence within the avialans, the study also re-shuffles the Troodontidae, a family of bird-like dinosaurs. Dr Godefroit and colleagues now consider these to be a sister group of the avialans.

"What we're arguing over here is actually very small, esoteric features of the anatomy," commented Dr Paul Barrett from the Natural History Museum, London, UK.

"We're looking at a nexus of animals around bird origins - birds themselves and a bunch of dinosaurs that are almost, but not quite, birds.

"There is a really grey, wobbly line between the two. Just one or two changes across a huge body of data can make the difference between an animal being on one side of this bird-dinosaur divide or the other.

Dr Barrett said the fossils now being unearthed were providing fascinating insights into the emergence of the bird line and the evolutionary "experimentation" that preceded it: "The beginnings of the bird line is all about fine-tuning parts of their anatomy - of their wings, of their hips, of their chest muscles and shoulder girdles, and so on - to make them flight-ready," he told BBC News.

http://www.bbc.co.uk/news/science-environment-22695914
Offline Profile Quote Post Goto Top
 
Jinfengopteryx
Member Avatar
Aspiring paleontologist, science enthusiast and armchair speculative fiction/evolution writer
[ *  *  *  *  *  *  *  * ]
This paper discusses the taxonomy of Archaeopteryx:

Archaeopteryx, which has often been considered the earliest avialan, is an iconic species, central to our understanding of bird origins. However, a recent parsimony-based phylogenetic study shifted its position from within Avialae, the group that contains modern birds, to Deinonychosauria, the sister-taxon to Avialae. Subsequently, probability-based methods were applied to the same dataset, restoring Archaeopteryx to basal Avialae, suggesting these methods should be used more often in palaeontological studies. Here we review two key issues: arguments recently advocated for the usefulness of probability-based methodologies in the phylogenetic reconstruction of basal birds and their close relatives, and support for different phylogenetic hypotheses. Our analysis demonstrates that Archaeopteryx represents a challenging taxon to place in the phylogenetic tree, but recent discoveries of derived theropods including basal avialans provide increased support for the deinonychosaurian affinities of Archaeopteryx. Most importantly, we underscore that methodological choices should be based on the adequacy of the assumptions for particular kinds of data rather than on the recovery of preferred or generally accepted topologies, and that certain probability methods should be interpreted with caution as they can grossly overestimate character support.

http://www.tandfonline.com/doi/abs/10.1080/14772019.2013.764357
Offline Profile Quote Post Goto Top
 
Taipan
Member Avatar
Administrator

Ancient Dinobird Wore Black and White

Tia Ghose, LiveScience Staff Writer
Date: 11 June 2013 Time: 07:06 PM ET

Posted Image
The mysterious dinobird archaeopteryx probably sported light-and-dark patterned plumage as illustrated here, new research suggests

A transitional species that represents a link between dinosaurs and birds may have sported pale feathers that were dark at the tips, a new study suggests.

For the study, detailed in the June 13 issue of the Journal of Analytical Atomic Spectrometry, researchers used an X-ray beam to identify ancient traces of pigment in fossils of Archaeopteryx, a winged creature that lived about 150 million years ago.

"This work refines our understanding of pigment patterning in perhaps the most important known fossil. Our technique shows that complex patterns were present even at the very earliest steps in the evolution of birds," said study co-author Roy Wogelius, an earth scientist at Manchester University in the United Kingdom, in a statement.

Rare bird

Archaeopteryx was a transitional species between dinosaurs and birds that lived in what is now Germany. Scientists believe birds evolved from theropods, a group of carnivorous dinosaurs taht includes the Tyrannosaurus rex, during the Jurassic Era, about 150 million years ago.

Only 11 fossils specimens of the elusive creature have been found, and scientists thought any traces of the dinobird's feathers had long since vanished.

But recently, researchers discovered that some fossilized feathers contained traces of melanosomes, pigment-making structures. Last year, researchers analyzed some of these melanosomes and determined that Archaeopteryx sported black feathers.

However, the team sampled just a few spots on the feather, meaning the dinobird's full plumage pattern was still unknown.

To get a more complete picture of the dinobird, Wogelius and his colleagues used an X-ray beam from a synchrotron radiation light source to do a complete scan of a fossilized Archaeopteryx feather, as well as pigmentation found in the surrounding rock.

The team discovered trace amounts of chemicals associated with pigments, which enabled a reconstruction of the animals' feather pattern.

Instead of being all black, it turns out Archaeopteryx sported light-and-dark patterned plumage.

"The fact that these compounds have been preserved in-place for 150 million years is extraordinary," said study co-author Phillip Manning, a paleontologist at the University of Manchester, in a statement. "Together, these chemical traces show that the feather was light in color with areas of darker pigment along one edge and on the tip. Scans of a second fossilized Archaeopteryx, known as the Berlin counterpart, also show that the trace-metal inventory supported the same plumage pigmentation pattern."

Understanding the plumage patterns could provide insights into courtship rituals, as well as the health and eating habits of these ancient creatures.

http://www.livescience.com/37351-dino-bird-had-patterned-feathers.html
Offline Profile Quote Post Goto Top
 
Taipan
Member Avatar
Administrator

Feathered dinosaurs had 'flight-ready' brains

By Melissa Hogenboom
Science reporter, BBC News
1 August 2013 Last updated at 08:10 GMT

Posted Image
Archaeopteryx is no longer regarded as the only missing link for the transition from dinosaur to bird

Several ancient dinosaurs evolved the brainpower needed for flight long before they could take to the skies, scientists say.

Non-avian dinosaurs were found to have "bird brains", larger than that of Archaeopteryx, a 150 million-year-old bird-like dinosaur.

Once regarded as a unique transition between dinosaurs and birds, scientists say Archaeopteryx has now lost its pivotal place.

The study is published in Nature.

A recent discovery in China which unveiled the earliest creature yet discovered on the evolutionary line to birds, also placed Archaeopteryx in less of a transitional evolutionary place.

Bird brains tend to be more enlarged compared to their body size than reptiles, vital for providing the vision and coordination needed for flight.

Scientists using high-resolution CT scans have now found that these "hyper-inflated" brains were present in many ancient dinosaurs, and had the neurological hardwiring needed to take to the skies.

This included several bird-like oviraptorosaurs and the troodontids Zanabazar junior, which had larger brains relative to body size than that of Archaeopteryx.

This latest work adds to previous studies which found the presence of feathers and wishbones on ancient dinosaurs.

Posted Image
Dinosaurs like the troodontid Zanabazar junior had enlarged "bird brains"

"Archaeopteryx has always been set up as a uniquely transitional species between feathered dinosaurs and modern birds," said lead author Amy Balanoff, of the American Museum of Natural History and Stony Brook University.

By studying the brains of closely related dinosaurs, she said that Archaeopteryx "might not have been so special".

"Large forebrains are typically correlated with things like increased cognition and parental care of the young, while not flying, they were definitely doing other things with these enlarged brains.

"A lot of these characteristics that are distinctive within birds evolved much earlier in the history of Theropods . It's interesting that the brain followed this pattern as well. The large brain evolved before flight earlier than was previously thought," Dr Balanoff told BBC News.

By compiling CT scans, the scientists created 3D reconstructions of dinosaur skulls as well as modern bird brains. They also calculated the total volume of each digital brain and determined the size of major anatomical regions such as the olfactory bulbs, cerebrum, optic lobes and cerebellum.

"The story of brain size is more than its relationship to body size," said co-author Gabriel Bever, of the New York Institute of Technology.

"If we also consider how the different regions of the brain changed relative to each other, we can gain insight into what factors drove brain evolution as well as what developmental mechanisms facilitated those changes."

Adrian Thomas at the department of zoology at Oxford University, who was not involved with the study, said the picture now is much more complicated than "dinosaurs couldn't fly and Archaeopteryx could".

"There were a whole group of more or less distantly related feathered dinosaurs, some were gliding down from trees, some were flapping, and it all seemed to be happening at the same time.

"Rather than a straight [evolutionary] path that led Archaeopteryx to birds, the picture now is that there were lots of dinosaurs exploiting the advantages of gliding and flight. The birds are the ones that carried on successfully to the present day," Prof Thomas told BBC News.

But he added that the "processing power required for flight is relatively simple" compared to walking and running.

"So it is interesting, but not a great surprise, to see increased brain size in these dinosaurs associated with their highly agile lifestyles."

Other ancient birds

Posted Image
Epidexipteryx

  • Epidexipteryx - a very small feathered dinosaur discovered in China and first reported in 2008 (above). It had four long tail feathers but there is little evidence that it could fly.

  • Jeholornis - this creature lived 120 million years ago in the Cretaceous. It was a relatively large bird, about the size of a turkey. First discovered in China, and reported in 2002.

  • Sapeornis - lived 110 to 120 million years ago. Another small primitive bird about 33 centimetres in length. It was discovered in China and was first reported in 2002.

  • Xiaotingia, a chicken-sized dinosaur which dates back 155 million years to the Jurassic Period, reported in 2011.

  • Aurornis, which means "dawn bird" lived about 160 million years ago, about 50cm tail to beak reported in China in 2013.


http://www.bbc.co.uk/news/science-environment-23514985

_____________________________________________________________________________________

Evolutionary origins of the avian brain
Amy M. Balanoff, Gabe S. Bever, Timothy B. Rowe & Mark A. Norell
Nature (2013) doi:10.1038/nature12424
Received 10 March 2013 Accepted 24 June 2013 Published online 31 July 2013

Abstract
Features that were once considered exclusive to modern birds, such as feathers and a furcula, are now known to have first appeared in non-avian dinosaurs. However, relatively little is known of the early evolutionary history of the hyperinflated brain that distinguishes birds from other living reptiles and provides the important neurological capablities required by flight. Here we use high-resolution computed tomography to estimate and compare cranial volumes of extant birds, the early avialan Archaeopteryx lithographica, and a number of non-avian maniraptoran dinosaurs that are phylogenetically close to the origins of both Avialae and avian flight. Previous work established that avian cerebral expansion began early in theropod history and that the cranial cavity of Archaeopteryx was volumetrically intermediate between these early forms and modern birds. Our new data indicate that the relative size of the cranial cavity of Archaeopteryx is reflective of a more generalized maniraptoran volumetric signature and in several instances is actually smaller than that of other non-avian dinosaurs. Thus, bird-like encephalization indices evolved multiple times, supporting the conclusion that if Archaeopteryx had the neurological capabilities required of flight, so did at least some other non-avian maniraptorans. This is congruent with recent findings that avialans were not unique among maniraptorans in their ability to fly in some form.

http://www.nature.com/nature/journal/vaop/ncurrent/full/nature12424.html
Edited by Taipan, Aug 2 2013, 05:53 PM.
Offline Profile Quote Post Goto Top
 
Taipan
Member Avatar
Administrator

Archaeopteryx: X-rays shine new light on mystery 'bird'

By James Morgan
Science reporter, BBC News, Grenoble
22 May 2014

Posted Image
How the scanning process works

The feathered limbs of Archaeopteryx have fascinated palaeontologists ever since Charles Darwin's day.

Only 12 of these curious creatures have ever been found.

Now these precious fossils are going under the glare of a giant X-ray machine - to find out what lies buried beneath the surface.

Using a new "camera obscura" technique - inspired by Leonardo da Vinci - scientists have captured some of the clearest ever images of Archaeopteryx.

For the first time, they can see the complete skeleton in 3D. Not just the surface outlines, but all the hidden bones and feathers too.

They hope to discover how "the first true birds" evolved from feathered dinosaurs and took flight.

And what's more, to answer a riddle that has puzzled palaeontologists for 150 years. Could Archaeopteryx fly, or not?

Posted Image
Could Archaeopteryx really fly?

The new tests are taking place at the European Synchrotron Radiation Facility (ESRF) in Grenoble, at the foot of the French Alps.

In the past, large fossil slabs were too bulky to be scanned in a synchrotron light source - a type of particle accelerator which generates high-energy X-rays.

But now scientists here are experimenting with a clever new trick, inspired by a very ancient and simple idea - the pinhole camera.

The basic concept has been around since at least 400 BC. But it was Leonardo da Vinci who made the first detailed drawings of a camera obscura in his 1485 sketchbook, Codex Atlanticus.

Light entering through a tiny hole is magnified and projected onto a screen wall.

Leonardo's camera allowed artists inside a tent to accurately trace and paint panoramic landscapes.

In a synchrotron, the pinhole system allows large fossils - too bulky to be rotated and scanned via conventional techniques (such as tomography) - to be captured in full by an extremely narrow X-ray beam.

"It's a beam that's only the thickness of a human hair. But extremely powerful. If you stood in front of it you would be killed," says Dr Paul Tafforeau, a palaeontologist at ESRF.

"As the beam goes through the sample you have diffusion of the X-rays and this diffusion pattern can be detected via the camera obscura - a very small hole in a piece of lead. Afterwards, you can reconstruct the images in 3D."

If their pinhole trick works as well on all dinosaur fossils as initial tests on Archaeopteryx suggest, it could open up new avenues in fossil research. The world's biggest, most famous dinosaur skeletons could be seen in a whole new light.

And so to demonstrate their proof of principle, the ESRF team began by summoning a very famous specimen.

Archaeopteryx caused a major stir when the first fossil was unearthed in 1861 - just two years after Charles Darwin published On The Origin of Species.

With the claws and teeth of a dinosaur, but the feathers of a bird, it was immediately recognised as a transitional form - proof of Darwin's theory.

Hailed as "the first true bird", the discovery shook the scientific community. Not bad for an animal as small as a magpie - only 20 inches from head to tail.

In recent years, more primitive bird ancestors have been unearthed in Liaoning, China. But the fascination with Archaeopteryx has endured - driven by the unsolved mystery over its ability to fly.

Around 150 million years ago, the modern-day region of Germany where Archaeopteryx lived was an archipelago of islands in a shallow tropical sea, covered in lush vegetation.

Posted Image
Archaeopteryx may have been a flightless predator scurrying among tropical trees

"We want to know how Archaeopteryx lived," says Martin Roeper, curator of the Solnhofen Museum, which houses one of the specimens.

"Was he a little dinosaur running, climbing trees - or was he flying? That's the most important question. Could Archaeopteryx fly or not?"

The answer grows closer as new, microscopic details of its anatomy emerge from ever more precise scans.

Blood vessels within the bones, for example, can be compared to modern birds.

Posted Image
Full scan of 'first bird' fossil

One by one, the 12 fossils have been arriving at the ESRF. And very soon there may be a major breakthrough to announce.

In the meantime: "What is really remarkable are the feathers - they are far more visible by this new scan than by looking at the original specimen," says Paul Tafforeau.

"But that's not all, because this technique reveals a lot about the anatomy that's not visible below the surface.

"You can see many hidden details inside the stone. With these we can better understand what Archaeopteryx really was."

If this X-ray spectacle can be repeated with other famous fossils, there may be other discoveries that ruffle the feathers of established wisdom.

And not only scientists will see the benefit, says Martin Roeper.

"In former times the visitors to our museum cannot easily understand the fossil - because they cannot see the feathers.

"But now that we see the whole wings - now everyone can see that Archaeopteryx really is a very fine specimen."

Posted Image

http://www.bbc.com/news/science-environment-27502354
Offline Profile Quote Post Goto Top
 
Taipan
Member Avatar
Administrator

Early bird Archaeopteryx 'wore feather trousers' for display

By James Morgan
Science reporter, BBC News
3 July 2014

Posted Image
Archaeopteryx


An ancient creature halfway between a dinosaur and a bird had feathered "trousers" on its hindlimbs.

Archaeopteryx had pennaceous (quill-like) feathers all over its body, not only its wings, a new fossil - only the 11th of the creature found - reveals.

These "trousers" were probably used for display, say scientists from Germany, writing in Nature journal.

Their discovery adds weight to the theory that feathers originally evolved for purposes other than flight.

Flight mystery

Archaeopteryx caused a major stir when the first fossil was unearthed in Germany in 1861 - just two years after Charles Darwin published On The Origin of Species.

With the claws and teeth of a dinosaur, but the feathers of a bird, it was clearly a transitional form - apparent proof Darwin's theory.

Its German name "Urvogel" means "first bird".

And though earlier bird-like dinosaurs have been unearthed since, many scientists still believe Archaeopteryx was the first capable of "flight" as we know it today.

The 11th fossil specimen was announced in 2011 and is remarkably well preserved, with detailed impressions of feathers all over its skeleton. The feathers are long and symmetrical on its upper leg and shorter lower down.

Posted Image
The skeleton is remarkably well preserved, showing detailed impressions of feathers

Previous specimens had shown some evidence of feathered hind legs but this "completes the picture", according to Dr Oliver Rauhut and colleagues at the Bavarian State Collection for Palaeontology and Geology.

These "trousers", as he describes them, may have been used for display, camouflage, insulation, brooding and manoeuvring while on the ground.

They were not primarily designed for flight but might have helped steady the bird during landing, similar to the hindlimb feathers of hawks, eagles and other modern raptors.

The wing feathers of the new specimen show robust shafts - further evidence that the "first bird" really could fly.

Recent studies assuming limited flight ability in Archaeopteryx "might be in error owing to the poorer preservation quality of the feathers," said Dr Rauhut.

"I'm pretty sure it could fly. Though of course there is still a debate about how well it could fly," he told BBC News.

The trousers are also a new clue to the mystery of how flight evolved in modern birds.

Traditionally it was thought that feathers and flight evolved hand in hand.

But the wide variation of plumages in early birds and feathered dinosaurs suggests that feathers first arose for a different purpose, said Dr Rauhut.

"Given the great diversity of pennaceous feathers found within different body regions and across the phylogeny, it seems plausible that the evolution of this feather type (especially in the wing, hindlimbs and tail) was primarily driven by display functions," he wrote in Nature.

Only later were these feathers recruited for flight - which may have arisen many times in parallel in different feathered species, he said.

Posted Image
The feathered "trousers" on the hind legs are clearly visible

http://www.bbc.com/news/science-environment-28129078




New specimen of Archaeopteryx provides insights into the evolution of pennaceous feathers

Christian Foth, Helmut Tischlinger & Oliver W. M. Rauhut
Nature 511, 79–82 (03 July 2014) doi:10.1038/nature13467
Received 30 January 2014 Accepted 12 May 2014 Published online 02 July 2014

Article metrics
Discoveries of bird-like theropod dinosaurs and basal avialans in recent decades have helped to put the iconic ‘Urvogel’ Archaeopteryx1 into context2, 3, 4, 5, 6 and have yielded important new data on the origin and early evolution of feathers7. However, the biological context under which pennaceous feathers evolved is still debated. Here we describe a new specimen of Archaeopteryx with extensive feather preservation, not only on the wings and tail, but also on the body and legs. The new specimen shows that the entire body was covered in pennaceous feathers, and that the hindlimbs had long, symmetrical feathers along the tibiotarsus but short feathers on the tarsometatarsus. Furthermore, the wing plumage demonstrates that several recent interpretations8, 9 are problematic. An analysis of the phylogenetic distribution of pennaceous feathers on the tail, hindlimb and arms of advanced maniraptorans and basal avialans strongly indicates that these structures evolved in a functional context other than flight, most probably in relation to display, as suggested by some previous studies10, 11, 12. Pennaceous feathers thus represented an exaptation and were later, in several lineages and following different patterns, recruited for aerodynamic functions. This indicates that the origin of flight in avialans was more complex than previously thought and might have involved several convergent achievements of aerial abilities.

Posted Image

http://www.nature.com/nature/journal/v511/n7507/full/nature13467.html
Offline Profile Quote Post Goto Top
 
1 user reading this topic (1 Guest and 0 Anonymous)
ZetaBoards - Free Forum Hosting
Create your own social network with a free forum.
« Previous Topic · Extinct Animals · Next Topic »
Add Reply

Skin created by Crash-Cheetah of Forum Chat