* Astronomy

Members Login
Username 
 
Password 
    Remember Me  
Post Info TOPIC: Sleeping Dinosaur


L

Posts: 131433
Date:
Fossilised dinosaurs
Permalink  
 


Fossilised dinosaurs often have wide-open mouths, heads thrown back and tails that curve toward the head. Palaeontologists have long assumed the dinosaurs died in water and the currents drifted the bones into that position, or that rigor mortis or drying muscles, tendons and ligaments contorted the limbs.

"I'm reading this in the literature and thinking, 'This doesn't make any sense to me as a veterinarian'" - Cynthia Marshall Faux, a veterinarian-turned-palaeontologist at the Museum of the Rockies.

Faux and a colleague say brain damage and asphyxiation are the more likely culprits.
A classic example of the posture, which has puzzled palaeontologists for ages, is the 150-million-year-old Archaeopteryx, the first-known example of a feathered dinosaur and the proposed link between dinosaurs and present-day birds.

"Virtually all articulated specimens of Archaeopteryx are in this posture, exhibiting a classic pose of head thrown back, jaws open, back and tail reflexed backward and limbs contracted" -  Kevin Padian, professor of integrative biology and curator in the Museum of Palaeontology at the University of California, Berkeley. He Faux (pronounced "Fox") published their findings this week in the journal Palaeobiology.

Some animals found in this posture may have suffocated in ash during a volcanic eruption, consistent with the fact that many fossils are found in ash deposits, Faux and Padian said. But many other possibilities exist, including disease, brain trauma, severe bleeding, thiamine deficiency or poisoning.

Read more

__________________


L

Posts: 131433
Date:
Xianglong zhaoi
Permalink  
 


An ancient treetop-living lizard that lived during the Early Cretaceous period about 150 million years ago glided through the air using a wing-like membrane stretched across elongated ribs, a new fossil found in China reveals.
Named Xianglong zhaoi, the specimen is about 15.5 cm long and its immature features suggest it died at a young age, according to details in the March 19 issue of the journal for the Proceedings of the National Academy of Sciences.
The fossil, described by Xing Xu of Shenyang Normal University and his colleagues, was discovered in the Liaoning Province in northeastern China, a site that has yielded a treasure trove of feathered dinosaurs and early bird remains in recent years.
Xianglong's gliding membrane, called a "patagium," is stretched across eight elongated dorsal ribs. Fully expanded, the layer of stretchy skin would have spanned about 4.5 inches across.
Xianglong had curved claws that would have enabled it to dwell in treetops, from whose high perch it could launch into the air. Once airborne, the little lizard could probably glide farther than modern flying lizards, perhaps as far as half a football field at a time.
The lizard's "wings" share several similarities with the wings of modern fast-flying birds, suggesting it might have been more nimble in the air than other gliding lizards.
Most gliding animals, such as "flying" frogs and squirrels, use a membrane spread between their toes or between their body and legs to stay airborne. A gliding membrane spread between elongated ribs is only known to occur in an ancient lizard-like animal that lived during the Late Triassic era and certain living dragon lizards in Southeast Asia.

"It is really amazing to see evolution making nearly identical structures in animals of different origins spanning such a long history" - Xing Xu.

Read more

-- Edited by Blobrana at 20:08, 2007-03-20

__________________


L

Posts: 131433
Date:
Dinosaur
Permalink  
 


A lifelong obsession with fossils led to Natural Sciences and Engineering Research Council grantee Robert Reisz discovering the oldest known dinosaur embryos and the oldest known reptile that stands on two legs.
Now, he is being honoured for more than 35 years of research excellence by joining the ranks of the American Association for the Advancement of Science (AAAS). The society will induct him as a fellow during its annual conference, being held from Feb. 15 to 19 in San Francisco.

"I am humbled that they chose me, and I think it was because my research has had an impact in my field.  I like to look at the very beginnings of major evolutionary events – to that time when mammals and reptiles and birds were just becoming separate from each other. It was an exciting time in history, about 270 million years ago – it was between ice ages, just like the time we are living in now – and I think my work has led to a greater understanding of what happened then" - Robert Reisz, palaeontologist at the University of Toronto.

Reisz earned three degrees in zoology at McGill University during the 1960s and 1970s, culminating in a doctorate in 1975. After spending a year at UCLA, he began research at the University of Toronto under an NSERC grant. He has remained at the university, continually funded by NSERC, ever since.
His research has spanned several countries, including Russia, Germany, the United States and Canada. His most recent discovery – finding 190-million-year-old dinosaur embryos in South Africa in 2005 – is part of a time period that is about 100 million years younger than the one he usually studies.

"I had a special research opportunity through NSERC to pursue this, and never expected it would be that successful. In fact, there will soon be an interpretive centre at the site where we found the embryos – the Golden Gate Highlands National Park in South Africa. It certainly is an honour to be recognised for my work."

Source : Natural Sciences and Engineering Research Council


__________________


L

Posts: 131433
Date:
Dinosaur eggs
Permalink  
 


 A nearly perfectly preserved fossilised nest of dinosaur eggs that may have been illegally taken from China was seized at a Los Angeles-area auction house by agents who were tipped off by a newspaper article
Bonhams & Butterfields sold the fossil specimen -- which is believed to contain the eggs of a predatory raptor from the Cretaceous Period -- at auction last December, but the sale was subsequently cancelled, according to an affidavit signed by a U.S. Immigration and Customs Enforcement agent.
Investigators are now trying to trace the fossil's origins. Officials say the specimen is so well preserved that remains of the dinosaur embryos are still visible inside the eggs.

Source Xinhua

__________________


L

Posts: 131433
Date:
Titanis walleri
Permalink  
 


Early humans could never have come into contact with the giant carnivorous "terror bird" Titanis walleri, research suggests.
It had been thought the fearsome beasts became extinct as little as 10,000 years ago - a time when humans shared their North American habitat.
But a US team has now revised this date to about two million years earlier.
The study, published in Geology, also sheds light on the flightless birds' migration to North America.

Read more

__________________


L

Posts: 131433
Date:
Red Gulch dinosaurs
Permalink  
 


Squatting in a small corral in a picturesque Rocky Mountain valley, palaeontologist Brent Breithaupt points excitedly at a patch of mud containing a large, fresh, three-toed footprint.

"Everything that we see in this track here can be found in the fossil record"

Read more

__________________


L

Posts: 131433
Date:
Terror bird
Permalink  
 


A University of Florida-led study has determined that Titanis walleri, a prehistoric 7-foot-tall flightless “terror bird,” arrived in North America from South America long before a land bridge connected the two continents.
UF palaeontologist Bruce MacFadden said his team used an established geochemical technique that analyses rare earth elements in a new application to revise the ages of terror bird fossils in Texas and Florida, the only places in North America where the species has been found. Rare earth elements are a group of naturally occurring metallic elements that share similar chemical and physical properties.

“It was previously thought that Titanis immigrated to Texas across the Panamanian land bridge that formed about 3 million years ago connecting North and South America. But the rare earth element analysis of a fossil Titanis bone from Texas determines its age to be 5 million years old. This shows that the bird arrived 2 million years before the land bridge formed, probably across islands that formed what today is the Isthmus of Panama” -  Bruce MacFadden, a curator of vertebrate palaeontology at the Florida Museum of Natural History at University of Florida.

The study will be published Jan. 23 in the online version of the journal Geology and featured in its February print edition.

Read more

__________________


L

Posts: 131433
Date:
Feathered fossil
Permalink  
 


The first flying dinosaurs took to the air in a similar way to a World War I bi-plane, a study shows. A fresh analysis of an early feathered fossil dinosaur suggests that it dropped its hind legs below its body, adopting a bi-plane-like form. This contrasts with earlier reconstructions showing the dinosaur maintaining its wings in a tandem pattern, a bit like a dragonfly.

Read more 



__________________


L

Posts: 131433
Date:
Feathered dinosaurs
Permalink  
 


When the Wright Brothers first took to the sky in a biplane, they were using a design nature may have tried 125 million years earlier. A new study of one of the earliest feathered dinosaurs suggests it may have had upper and lower sets of wings, much like the biplanes of early aviation. Today, the biplane is widely considered an old-fashioned rarity.
And the design is no longer seen in birds, though it's not clear if it was a step on the way to modern birds or a dead end, tested by nature and discarded.
The intriguing possibility of a biplane dinosaur - Microraptor gui - is suggested by Sankar Chatterjee of Texas Tech University in this week's online issue of Proceedings of the National Academy of Sciences.
Microraptor was described by Xing Xu of the Chinese Academy of Sciences in 2003 as having aerodynamic feathers on both its arms and legs. Xu suggested at the time that it glided, extending its legs backward so its wings were arranged one behind the other, like a dragonfly.
But that would be aerodynamically inefficient for a feathered creature, Chatterjee concluded, noting that the feathers on the legs would not face forward.
Instead, he suggested, the legs of the two-pound creature could have been held below the body in flight, creating two staggered wing sections, the upper one slightly ahead of the lower one.
One other flying dinosaur, Pedopenna, also had feathers on its legs, and modern raptors such as falcons have short feathers on their upper legs which reduce air resistance as they fly.
Matthew Carrano, curator of dinosaurs at the Smithsonian's National Museum of Natural History, said the question focuses on what the legs can do, and it's a difficult problem because the fossils are flat and require interpretation as to what they would have looked like in three dimensions.
Carrano, who also was not part of Chatterjee's research team, said this creature was probably a side branch rather than a stage evolution had to pass through on the way to today's birds.

Source: PNAS

__________________


L

Posts: 131433
Date:
Terror bird
Permalink  
 


Palaeontologists have finally found out how the giant phorusrhacids moved about swiftly despite its large body and head size.
Luis Chiappe of the Natural History Museum of Los Angeles County, California says a study of the foot bones of a new fossil unearthed in northern Patagonia has revealed that the killer birds had long, slender feet like those of modern fast-runners such as the emu or ostrich.

Read more

__________________
«First  <  18 9 10 11  >  Last»  | Page of 11  sorted by
Quick Reply

Please log in to post quick replies.



Create your own FREE Forum
Report Abuse
Powered by ActiveBoard