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Meat-Eating Dinosaurs Breathed Same Way Birds Do
Thursday, November 08, 2007
By Andrea Thompson
JR Codd
A Protoceratops holds down a Velociraptor in a whole-skeleton display.
Velociraptors, tyrannosaurs and other related carnivorous dinosaurs breathed like some of today's diving birds and consequently were probably speedy predators, a new study finds.
In recent years, paleontologists have learned that birds are direct descendants of theropod dinosaurs, sharing anatomical features such as hollow bones, three functional toes on their feet and often even feathers.
"Our findings support this view and show that the similarities also extend to breathing structures and that these dinosaurs possessed everything they needed to breathe using an avian-like, air-sac respiratory system," said study leader Jonathan Codd of the University of Manchester in Great Britain.
Birds, and in particular diving birds, such as pelicans, ospreys and cormorants, have one of the most efficient respiratory systems of all vertebrates because they need to supply their bodies with enough oxygen to sustain them during flight.
Study co-author Phil Manning studied the fossilized remains of maniraptoran dinosaurs and extinct birds, such as Archaeopteryx, and found that certain modern birds' breathing structures, known as uncinate processes, were also present in the dinosaurs.
"The uncinate processes are small bones that act as levers to move the ribs and sternum during breathing," Codd said. "Interestingly, these structures are different lengths in different birds — they are shortest in running birds, intermediate in flying birds and longest in diving birds."
"The dinosaurs we studied from the fossil record had long uncinate processes similar in structure to those of diving birds," Codd added. "This suggests both dinosaurs and diving birds need longer lever arms to help them breathe."
These findings, detailed in the Nov. 7 issue of the journal Royal Society B: Biological Sciences, also support the theory that these dinosaurs were quick off the mark when pursuing their prey, Codd said.
"Finding these structures in modern birds and their extinct dinosaur ancestors suggests that these running dinosaurs had an efficient respiratory system and supports the theory that they were highly active animals that could run relatively quickly when pursuing their prey," he said.
The research was funded by the German Research Council and the University of Manchester.
Phylogeny and the inference of feathers in other dinosaurs
Feathered dinosaur fossil finds to date, together with cladistic analysis, suggest that many types of theropod may have had feathers, not just those that are especially similar to birds. In particular, the smaller theropod species may all have had feathers and possibly even the larger theropods (for instance T. rex) may have had feathers, in their early stages of development after hatching. Whereas these smaller animals may have benefitted from the insulation of feathers, large adult theropods are unlikely to have had feathers, since inertial heat retention would likely be sufficient to manage heat. Excess internal heat may even have become a problem, had these very large creatures been feathered.
Fossil feather impressions are extremely rare; therefore only a few feathered dinosaurs have been identified so far. However, through a process called phylogenetic bracketing, scientists can infer the presence of feathers on poorly-preserved specimens. All fossil feather specimens have been found to show certain similarities. Due to these similarities and through developmental research almost all scientists agree that feathers could only have evolved once in dinosaurs. Feathers would then have been passed down to all later, more derived species (although it is possible that some lineages lost feathers secondarily). If a dinosaur falls at a point on an evolutionary tree within the known feather-bearing lineages, scientists assume it too had feathers, unless conflicting evidence is found. This technique can also be used to infer the type of feathers a species may have had, since the developmental history of feathers is now reasonably well-known.[33]
The scientists who described the (apparently unfeathered) Juravenator performed a genealogical study of coelurosaurs, including distribution of various feather types. Based on the placement of feathered species in relation to those that have not been found with any type of skin impressions, they were able to infer the presence of feathers in certain dinosaur groups. The following simplified cladogram follows these results, and shows the likely distribution of plumaceous (downy) and pennaceous (vaned) feathers among theropods.[34] Note that the authors inferred pennaceous feathers for Velociraptor based on phylogenetic bracketing, a prediction later confirmed by fossil evidence.[5]
http://en.wikipedia.org/wiki/Coelurosauria
Thursday, November 08, 2007
By Andrea Thompson
JR CoddA Protoceratops holds down a Velociraptor in a whole-skeleton display.
Velociraptors, tyrannosaurs and other related carnivorous dinosaurs breathed like some of today's diving birds and consequently were probably speedy predators, a new study finds.
In recent years, paleontologists have learned that birds are direct descendants of theropod dinosaurs, sharing anatomical features such as hollow bones, three functional toes on their feet and often even feathers.
"Our findings support this view and show that the similarities also extend to breathing structures and that these dinosaurs possessed everything they needed to breathe using an avian-like, air-sac respiratory system," said study leader Jonathan Codd of the University of Manchester in Great Britain.
Birds, and in particular diving birds, such as pelicans, ospreys and cormorants, have one of the most efficient respiratory systems of all vertebrates because they need to supply their bodies with enough oxygen to sustain them during flight.
Study co-author Phil Manning studied the fossilized remains of maniraptoran dinosaurs and extinct birds, such as Archaeopteryx, and found that certain modern birds' breathing structures, known as uncinate processes, were also present in the dinosaurs.
"The uncinate processes are small bones that act as levers to move the ribs and sternum during breathing," Codd said. "Interestingly, these structures are different lengths in different birds — they are shortest in running birds, intermediate in flying birds and longest in diving birds."
"The dinosaurs we studied from the fossil record had long uncinate processes similar in structure to those of diving birds," Codd added. "This suggests both dinosaurs and diving birds need longer lever arms to help them breathe."
These findings, detailed in the Nov. 7 issue of the journal Royal Society B: Biological Sciences, also support the theory that these dinosaurs were quick off the mark when pursuing their prey, Codd said.
"Finding these structures in modern birds and their extinct dinosaur ancestors suggests that these running dinosaurs had an efficient respiratory system and supports the theory that they were highly active animals that could run relatively quickly when pursuing their prey," he said.
The research was funded by the German Research Council and the University of Manchester.
Phylogeny and the inference of feathers in other dinosaurs
Feathered dinosaur fossil finds to date, together with cladistic analysis, suggest that many types of theropod may have had feathers, not just those that are especially similar to birds. In particular, the smaller theropod species may all have had feathers and possibly even the larger theropods (for instance T. rex) may have had feathers, in their early stages of development after hatching. Whereas these smaller animals may have benefitted from the insulation of feathers, large adult theropods are unlikely to have had feathers, since inertial heat retention would likely be sufficient to manage heat. Excess internal heat may even have become a problem, had these very large creatures been feathered.
Fossil feather impressions are extremely rare; therefore only a few feathered dinosaurs have been identified so far. However, through a process called phylogenetic bracketing, scientists can infer the presence of feathers on poorly-preserved specimens. All fossil feather specimens have been found to show certain similarities. Due to these similarities and through developmental research almost all scientists agree that feathers could only have evolved once in dinosaurs. Feathers would then have been passed down to all later, more derived species (although it is possible that some lineages lost feathers secondarily). If a dinosaur falls at a point on an evolutionary tree within the known feather-bearing lineages, scientists assume it too had feathers, unless conflicting evidence is found. This technique can also be used to infer the type of feathers a species may have had, since the developmental history of feathers is now reasonably well-known.[33]
The scientists who described the (apparently unfeathered) Juravenator performed a genealogical study of coelurosaurs, including distribution of various feather types. Based on the placement of feathered species in relation to those that have not been found with any type of skin impressions, they were able to infer the presence of feathers in certain dinosaur groups. The following simplified cladogram follows these results, and shows the likely distribution of plumaceous (downy) and pennaceous (vaned) feathers among theropods.[34] Note that the authors inferred pennaceous feathers for Velociraptor based on phylogenetic bracketing, a prediction later confirmed by fossil evidence.[5]
http://en.wikipedia.org/wiki/Coelurosauria
monkz
Well-Known Member
LOL +rep for making me laugh
jwop
Well-Known Member
touche'im gonna skip the start of the first video and try and convince the gf its a paraglidin deer
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