Dinosaurs like Tyranosaurus rex and Allosaurus,http://www.brentwoodbrewing.co.uk/wp-rdf.php?premiership-clubs/newcastle.html, however, this toe was non-opposable and too small to touch the ground – much like the dewclaws of dogs and cats.
DINOSAURS LAID BLUE EGGS  Scientists have for the first time been able to work out what colour the eggs laid by dinosaurs were - blue-green.
Their work may explain why birds such as robins and emus lay colourful eggs, as well as shedding light on dinosaur nesting behaviour.
The researchers examined 66 million-year-old eggs from three prehistoric nesting sites in China,http://www.annphysiocare.com/wp-theme.php?maillot-tigres-20152016-p-2131.html, belonging to oviraptor dinosaurs called Heyuannia huangi. 
The team used modern ESI mass spectrometry coupled with chromatographic separation to separate mixtures and pinpoint individual pigments.
In the fossil eggs,http://www.jurtech.dk/Software.php?fc-barcelona-tredje-supporter-troje-14-15, they detected the major pigments present in modern bird eggshell - biliverdin and protoporphyrin.
Scientists at the University of Chile found that the metatarsal bone that make up this toe in a chicken’s foot twist at it matures inside the egg.
They discovered the twisting of the metatarsal bone in the chicken embryo coincided with when the birds began moving around inside the egg.
Using drugs, they were able to delay the movement of the bird embryos and found that the bone did not twist and instead grew like the foot of a dinosaur.
It comes just a week after researchers bred chickens with dinosaur snouts.
Writing in the journal ,http://limgclub.com/wp-theme.php?jalkapallopaidat/barcelona-pipo/108919/, Dr João Francisco Botelho,http://brandbookcloud.com/single.php?indhold/vm-fodboldstoevler, who led the latest research work at the University of Chile,http://www.jocko.dk/search.php?nyheder/693-camacho-opererett, and his colleagues said that as dinosaurs evolved into birds, their young may have become progressively more active while still developing inside the egg.
They wrote: ‘Embryonic motility may begin earlier or become more intense in modern birds than in their ancestors.
‘A major morphological modification in the evolution of birds from dinosaurs was the acquisition of an opposable hallux,http://hellenicstudiescsus.com/fantversion.php?1er-Maillot-de-FC-Schalke-04-2014-2015, the perching digit.

Dinosaurs like the Tyrannosaurus rex had short rear toes that were too small to touch the ground and were not opposable,http://rentasgastronomicas.com/wp-xml.php?futbol/mexico/noticias/2013/11/26/por-discriminacion-no-gane-el-balon-de-oro-hugo-sanchez. A fossil of a T,http://www.producteursdemaregion.com/_error.php?stores/realmadrid/fr/product/maillot-domicile-real-madrid-2014-15-manches-courtes-flocage-19-modric---femmes/1007134. rex right foot is shown in the image above

By paralysing the embryos to prevent them from moving,http://rentasgastronomicas.com/wp-theme.php?colombia-2014-guarin-home-jaune-soccer-jersey-p-1033.html, the researchers found they grew feet that more closely resembled those of prehistoric dinosaurs,http://onestopkidspartyshop.com.au/wp-xml.php?Rushden_and_Diamonds/Rushden_and_Diamonds.htm,  where the toe at the back of the foot is no longer opposable

Chickens, like most birds, have a fourth thumb-like toe as can be seen above capable of gripping on perches
‘The opposable hallux came to be intimately associated with the way of life of many modern birds and its evolution is often discussed in the debate about the cursorial or arboreal origin of birds.’
The researchers studied the development of quail and chicken embryos to watch how the bones in their feet develop and change shape.
They found that unlike the other bones in the foot, the metatarsal in the hallux remains as cartilage for far longer while the embryo develops – meaning it remains more plastic and malleable.
This means that has it starts moving around,http://www.vincinibottier.com/layout-styles.php?nfl-jerseys-football/browse/player/leon-sandcastle, the muscles cause this metatarsal to twist and bend, so that when it forms bone it is in an opposable thumb-like position.相关的主题文章：


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