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ramonmercado Psycho Punk
Joined: 19 Aug 2003 Total posts: 17933 Location: Dublin Gender: Male |
 Posted: 15-08-2013 13:06 Post subject: |
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| Quote: | Ostrich necks give clues to dinosaur flexibility
By Melissa Hogenboom
http://www.bbc.co.uk/news/science-environment-23679932
Science reporter, BBC News
Artwork of four Brachiosaurus dinosaurs feeding in a forest of tree ferns next to snow-capped mountains
A thick mass of neck muscle restricted the range over which the dinosaurs could reach
The familiar view of sauropod dinosaurs reaching out for vegetation using their long, graceful necks may not be entirely accurate, say scientists.
A study of modern-day ostriches suggests the ancient animals were probably quite stiff in their movement.
Sauropod dinosaurs had a thick mass of muscle in their necks and the researchers say this would probably have restricted the range over which the beasts could move their heads.
The study is published in Plos One.
Its authors say the findings have implications for the way we display the dinosaurs in museum exhibits and in the media.
Computer modelling that has been used to simulate sauropod movements will not have portrayed the lack of neck flexibility accurately, the team adds.
For example, the BBC's landmark TV series Walking with Dinosaurs modelled the neck movement using the position of the vertebrae.
But this did not account for the effects of soft tissues like muscle and cartilage, which this new study tries to incorporate by looking at ostriches.
The team, led by Matthew Cobley from the University of Utah, US, has shown that muscle mass reduces the maximum flexibility of ostrich necks.
The researchers measured the flexibility of the flightless birds with all their muscle tissue intact, and then slowly removed the muscles to test how this changed the situation.
As they are the largest birds to exhibit elongated necks, with vertebrae and musculature broadly comparable to those of sauropods, ostriches provide useful insights into the past.
"Previous studies looked at the skeleton on its own and the assumption was that flexibility is limited by the bones of the skeleton, but our study shows it's actually the soft tissue around it," said Mr Cobley.
He added that computer modelling of any biological system needed to be "ground-truthed" before it was accepted by the scientific community and presented to the public.
Ostrich
The long-necked ostrich gives scientists clues about its sauropod relative
"It's easy to be swayed by these beautifully reconstructed models of dinosaurs, but if these models aren't based on real, empirical data taken from living animals we can actually study, they only serve to confuse the general public."
The amount of cartilage in the neck and varying distances between vertebral joints could also have caused reduced flexibility, the research found.
A common sauropod picture in films and museums is a creature reaching from high tree-tops to food that's very low on the ground, but this new work could now change how the animals are depicted.
It suggest the lack of flexibility may have restricted the range of food to which the the dinosaurs had access. And they may have had to work harder for their food - the hefty herbivores needed about 400kg of plant-based material each day.
"Different sauropods were limited to different food types. It's why you don't see giraffes eating from bushes from the floor or goats eating from the tree-tops," Mr Cobley told BBC News.
"There was a better division of resources between dinosaurs, with the taller ones limited to taller trees and smaller ones to grazing bushes on the floor."
Michael Benton of Bristol University, UK, commenting on the research, said the study "provides food for thought" and a warning about reconstructing sauropod necks without considering the distribution of soft tissues.
"Formerly, people assumed a standard amount of soft tissue that would limit flexibility, but it is rather more complex, and some previous reconstructions of sauropod necks snaking around must be modified," Prof Benton told BBC News. |
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| rynner2 What a Cad!
Great Old One Joined: 13 Dec 2008 Total posts: 21365 Location: Under the moon Gender: Male |
| Posted: 10-09-2013 22:15 Post subject: |
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Science 'could lose' duelling dinos
By Simon Redfern, Science reporter, BBC News
Rare dinosaur remains could be forever lost to the scientific community when they go under the hammer in November.
The remarkably preserved fossils of two "duelling" dinosaurs frozen in a death clinch could fetch up to $10m.
But scientists want the opportunity to examine the specimens of the tyrannosaur, which appears to have bitten off more than it could chew.
Details of the discovery, from Montana, US, were discussed at the British Science Festival in Newcastle.
The large arms and thin head of this most complete tyrannosaur ever discovered suggest it is a new species, called Nanotyrannus, living alongside and related to T. rex.
The observations were made by Dr Phil Manning of Manchester University.
Some 65 to 67 million years ago, in an area that now lies the middle of Montana, T. rex was the top predator of the ecosystem. Dr Manning has just returned from an excavation of a new T. rex skeleton that he is preparing for a museum in Leiden, Germany.
Fossil fragments of T. rex are found throughout the rocks called the "Hell Creek Formation" in Montana, but never before has an entire tyrannosaur skeleton been found.
Only two T. rex skeletons that are more than half complete have been ever been recovered. The Fields Museum in Chicago has the most complete T. rex, at 85% of a skeleton, which was bought at auction for a record sum, and the Black Hills Museum in South Dakota has a 65% complete T. rex.
There has been great excitement, therefore, over the recent excavation of an entire and complete tyrannosaur predator from the Hell Creek Formation. More than that, it was found forever frozen in a linked death clasp with its prey, a complete Triceratops.
Dr Phil Manning from the University of Manchester explained at the British Science Festival in Newcastle how new observations show a tooth from the tyrannosaur embedded between the neck vertebrae of the Triceratops, while the skull of the tyrannosaur appears to have been shattered by a blow from the Triceratops.
"It was a bad day for both of them" quipped Dr Manning. "These animals could have been fighting on the banks of a river. They both became mortally injured." They were then rapidly buried and preserved as fossils.
But there is more to this remarkable death duelling pair than the preservation of their last moments as entire skeletons. The preservation also solves a longstanding scientific question.
In 1988, a similar skull bone from a predatory dinosaur was identified as a distinct species, which was then named Nanotyrannus, but the identification from one skull fossil was not widely accepted, with many suggesting that this was simply a young T. rex.
The dispute over whether a second large predator lived alongside T. Rex has rumbled on over the last decades, but Dr Manning's observations of the new entire skeleton help resolve the issue.
T. rex has some notable distinctive features, one of which is its very small arms. Dr Phil Manning has just returned from a visit to inspect the new specimen from Montana, and described its very large fore arms. Despite being about half the body size of an adult T. rex the arms of Nanotyrannus are noticeably larger than those of T. rex.
Nanotyrannus is characterised by Dr Manning as having its own ecological niche, with a long swan-like neck, relatively large fore arms, and a narrower gracile skull. "If you think of the savannah of Africa today, the lion is taking down the big prey and the cheetah is maybe taking down the small prey. Maybe we are looking at the cheetah of the Cretaceous here: we've got similar niche partitioning of the ecosystem that existed 65 to 67 million years ago".
"When you have a big predator, like T. rex, it means that you have a healthy established ecosystem. So it's not surprising to find a more complex system in place at the end of the Cretaceous" Dr Manning explained.
Dr David Norman of the University of Cambridge was not involved in the study. He commented to the BBC "A really nice skull has been described previously, and looks rather low and long compared to a classic T. rex skull, which led to the suggestion of Nanotyrannus.
"If this new specimen has larger forelimbs and a gracile skull on a more slender swan-like neck, it provides plausible reasons to substantiate the idea that this is a new genus."
The remarkable specimen was discovered on private land by an independent fossil collector, and is now being offered for sale by auction. It is expected to fetch as much as $10m dollars when it goes under the hammer in November.
The scientific community demands that original research material like this sample be deposited in accessible museum collections if the description or discoveries of new species or genus are to be accepted, to allow observations to be verified and studied openly by others.
The auction of the Nanotyrannus - Triceratops pair may yet stymie the acceptance of Nanotyrannus as a new species. If it goes to a private collection it will no longer be available to science, and the unique observations made thus far will never be subject to peer-scrutiny.
The whole issue of the commercialisation of fossil discovery is raising concerns among palaeontologists and other scientists, and may hinder future discovery, they say.
Discussing the issue, Dr Norman commented: "This is the most distasteful part of it. Ever since the T. rex was sold to the Fields Museum in Chicago for $8m, the commercial value of fossils has been hyped.
"This spiralling effect means that more and more scientifically important objects risk being removed from the community for scientific study. They fall into private hands because they become objects d'art.
"It destroys the whole ethos of the availability of specimens. These fossils were left by Nature, shouldn't they be available to be appreciated and studied by everybody, rather than falling into private hands?
"There are national issues about how fossils are sold and valued that vary from country to country. It is becoming a minefield now that fossils can have a high value, and makes it a curatorial nightmare for museums."
http://www.bbc.co.uk/news/science-environment-24033966 |
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| ramonmercado Psycho Punk
Joined: 19 Aug 2003 Total posts: 17933 Location: Dublin Gender: Male |
| Posted: 19-09-2013 15:38 Post subject: |
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| Quote: | Dinosaur in a wind tunnel tests feathered flight
http://www.newscientist.com/article/dn24218-dinosaur-in-a-wind-tunnel-tests-feathered-flight.html#.UjsMJcZ6ZvI
10:00 18 September 2013 by Alyssa Botelho
Video: Microraptor in wind tunnel reveals flight secrets
A life-sized model of a dinosaur has been suspended in a wind tunnel to help test how feathered dinosaurs might have taken to the air roughly 125 million years ago.
The results suggest that the small, four-winged creatures of the genus Microraptor would have been efficient gliders even without feathers. This supports the idea that plumage might not have evolved for flight but may instead have been a key aspect of sexual-selection displays.
The creatures lived during the early Cretaceous period and are a genus of dromaeosaurs – two-legged predatory dinosaurs that are related to birds. The first microraptor with preserved feathers was unearthed in China in 2003, showing long plumes on all four of its limbs. This set off a firestorm of debate about how the animal might have moved through the air, since this could offer clues to how bird ancestors first put their limbs to the task of gliding and flapping.
Model flyer
One of the fiercest points of contention was microraptors' leg positioning: were the legs splayed parallel to the forearms to form two pairs of wings, like a biplane? Or were they folded beneath its body, like the legs of modern raptors catching prey?
"For years scientists thought microraptors could fly but weren't sure how," says Gareth Dyke at the University of Southampton in the UK. For their tests, Dyke and his colleagues fashioned the first full-scale, anatomically accurate model of a microraptor from balsa wood, aluminium and mallard feathers. The model, dubbed Maurice, weighs in at about half a kilogram and has a 60-centimetre wingspan.
Maurice was suspended in a wind tunnel by piston-tipped poles, which allowed the team to alter the legs and tail mid-flight (see video, above). The model was then exposed to gusts of up to 20 metres per second. Airflow analysis suggests that the dinosaur probably could have switched between its possible leg configurations mid-air, and that either one would have allowed it to glide in roughly the same way.
Squirrely dino
Overall, microraptors would have been most stable in a slow glide that is less aerodynamically efficient but would have resulted in minimal height loss and longer flight distances. That kind of movement would have been ideal for an animal that combined arboreal and ground-based foraging by scampering up trunks and gliding between trees, like a modern-day flying squirrel, says Dyke.
What's more, Maurice's flight capabilities did not change when his feathers were removed. "The most important thing for this dinosaur was maximising wing surface rather than the presence of feathers," says Dyke.
"That's a key thing, because for many years scientists thought feathers were unique to birds as a great adaption for generating flight. But it seems almost 100 per cent certain that feathers evolved for something else. We just have to figure out what for."
Journal reference: Nature Communications, DOI: 10.1038/ncomms3489 |
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