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The jumbo killer claws of dinosaur such asVelociraptormight have been employ much as birds of quarry use similar talons — as draw to keep victims from escaping , researchers say .
The discovery could also shed visible radiation on the origin of escape in birds , investigator added .
This picture shows a small dromaeosaur in side view. The forelimbs are wrapped around the prey, preventing escape as the dinosaur dispatches its victim with its teeth.
Theraptor dinosaur , made famous by the book and picture " Jurassic Park " all possess remarkably big , curving talonson the second toes of each fundament , which they held off the soil likefolded flick-knife . Known more officially as dromaeosaurids , they included the famousVelociraptorand its big relativeDeinonychus , and were intimately related to chick .
Past studies had proposed that the sickle claws of these raptors were used to slash at quarry or to help climb onto victims . Now research into advanced - daybirds of preysuggests a fresh possible killing technique — as hooks to mesh onto mark .
The 2d toe
A dromaeosaurid dinosaur stands atop its prey, using the enlarged sickle claw of the foot to maintain its position.
scientist noted that modern hawks and bird of Jove own similar enlarged claws on their 2nd toe — the " digit twos " or " D-2s . " These claws " are used as anchorperson , latching into the prey , preclude their leakage , " said investigator Denver Fowler , a paleobiologist at the Museum of the Rockies in Bozeman , Mont. " We interpret the sickle claw of dromaeosaurids as having evolved to do the same thing — latch in and holding on . " [ In picture : wench of Prey ]
" This strategy is only really needed for prey that are about the same size of it as the predatory animal — large enough that they might struggle and break loose from the feet , " Fowler say . " Smaller quarry are just squeeze to death , but with big prey all the vulture can do is hold up on and stop it from escaping , then basically just eat it live . "
" Dromaeosaurs lack any obvious adaptations for dispatch their victims , so just like hawk and eagles , they probably ate their prey awake too , " Fowler enounce .
Dinosaur feet are adapted for different purposes. Dinos adapted for running and walking tend to have a large middle toe with side toes that are shorter and about equal in length, like A (Gallimimus) and B (Allosaurus).Deinonychus(C) has an unusually long outer toe and a short inner toe, more suitable for grasping.
Other features of the feet of these dinosaurs suggest they followed what Fowler and his fellow call " Raptor Prey Restraint " — RPR , or " ripper . " For instance , the toe proportions of raptors seem more suited for grasping than running , and the metatarsus — which includes the bone between the ankles and the toes — is more adapted for strength than speeding .
" Unlike human , most dinosaurs and bird only walk on their toe , so the metatarsus form part of the branch itself , " Fowler aver . " A long metatarsus Lashkar-e-Tayyiba you take bigger strides to run faster , but in dromaeosaurids , the metatarsus is very short . "
All in all , Velociraptorand its kin do not seem adapted to simply run after prey .
" When we appear at modern birds of prey , a relatively little metatarsus is one feature that yield the chick additional potency in its foot , " Fowler say . " VelociraptorandDeinonychusalso have a very scant , stout metatarsus , propose that they had great strength but would n’t have been very libertine runners . "
Such behavior intriguingly contrasts with that of their closest known relatives , a very similar radical of small carnivorous dinosaurs called troodontids .
" Troodontids and dromaeosaurids started out looking very similar , but over about 60 million years , they evolved in diametrical direction , adapting to different niches , " say Fowler . " Dromaeosaurids evolve towards stronger , slower feet , suggest a stealthy ambush predatory scheme , adapted for relatively big prey . By contrast , troodontids evolved a long metatarsus for upper and a more exact , but weaker bag , suggesting they were fleet but in all probability took relatively small prey . "
Evolution of flapping
These determination could shed light on theevolution of flight of steps in bird , researcher said . Such pes could have lead to the evolution of flapping .
" When a New hawk has latched its magnified claw into its prey , it can no longer habituate the feet for stabilisation and placement , " Fowler said . " Instead , the predator flaps its wing so that the prey stay underneath its feet , where it can be pinned down by the predator ’s trunk weightiness . The predator ’s flap just maintains its place , and does not necessitate to be as powerful or vigorous as full flight would ask . Get on top , delay on top — it ’s not seek to fly off . "
In much the same way , raptor dinosaurs might have dither their feathery tree branch to keep stable . [ Photos of Fossil Feathers ]
" We see in full formed wing in exquisitely preserved dromaeosaurid fossils , and from biomechanical studies we can show that they were also able to perform a rudimentary wave stroke , " Fowler say . " Most research worker think that they were n’t sinewy enough to take flight — we advise that the less demanding stability - flapping would be a viable consumption for such a wing , and this behavior would be reproducible with the unusual adaptations of the foot . "
" There ’s an onetime question on the evolution of flight — ' what use of goods and services is half a wing ? ' " Fowler told LiveScience . " I think we have offer the most complete and defendable answer . "
Eventually , grasping metrical unit could have become perching feet .
" A grasp foot is present in the close relatives of birds , but also in the earliest chick likeArchaeopteryx , " Fowler tell . " We suggest that this in the beginning evolve for predation , but would also have been available for economic consumption in perching . This is what we call ' exaptation ' — a structure develop in the beginning for one purpose that can afterwards be appropriated for a different use . "
This enquiry could help explain the anatomy of some recently describedpeculiar dinosaur . For illustration , the dromaeosaurBalaur , recently unearth in Romania , " has a very short fused - up metatarsus and a apparently expatiate claw , not only on the second toe , as in other dromaeosaurs , but the first toe as well , " Fowler tell . " This is jolly unusual , but base on our model , this make sense . "
The scant meld - up metatarsus can be seen as an uttermost form of the short extensive metarsus of other dromaeosaurids , while the blown-up pincer on the first toes might function the same anchoring function as the ones on the 2d toe do . " Balaurlooks like it was a super - dromaeosaur , with the predatory features of normal dromaesaurs taken to extreme bill , " Fowler said .
The researchers believe their melodic theme will afford unexampled lines of investigating into dinosaur biology . New ways of look at old anatomic social organisation could help solve the enigma of why the feature develop and how they were used .
" Just as you have to get beyond the musical theme that invertebrate foot are used just for walk , so we are hail to realize that many strange structure in modern animals primitively evolved for quite different purpose , " Fowler said .
The scientists detail their findings onlineDec . 14 in the daybook PLoS ONE .
