Films like Jurassic Park have led us to believe that Tyrannosaurus rex was capable of chasing down its prey at full tilt. New research done with simulations suggest this dino was no sprinter, and that it couldn’t move any faster than a brisk walk. Well, a brisk walk for a nine ton carnivore. At a top speed of 12 miles per hour, you’d still be hard pressed to outrun this prehistoric beast. 
 
 
 
 New research published in PeerJ suggests the size and weight of a T. rex would have prevented it from running, and that it couldn’t move any faster than 5.4 meters per second, or 12 miles per hour. Any faster, and the leg bones of this biped would have collapsed and buckled under the tremendous weight. This means that T. rex was unable to pursue its prey at high speeds—but high speed is a relative term. For reference, typical humans can sprint anywhere between eight to 15 miles per hour (elite athletes can exceed 20 mph). So to outrun a T. rex, many animals—or fictional humans—would still have to run like hell. 
 
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 Paleontologists have been debating T. rex’s running ability for decades. At the high end, some research has suggested that T. rex could run a blistering 20 meters per second (45 mph), while more recent research has suggested a more manageable pace around five to 11 meters per second (11 to 18 mph). This latest study, led by William Sellers from Manchester University’s School of Earth and Environmental Sciences, affirms the low end of these estimates, while also demonstrating, through the use of computer simulations, that T. rex was incapable of running. Instead, the study suggests it walked briskly in a “bird-like” manner. 
 
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 For the analysis, Sellers combined two established techniques used to study the biomechanical properties of animals, namely multibody dynamic analysis (MBDA) and skeletal stress analysis (SSA). This is the first time paleontologists have combined the two approaches, and it’s creating a more accurate portrait of dinosaur physiology. Previous simulations failed to consider the effect of “skeletal loading,” that is, the limits to how much pressure bones can bear before snapping. For the new study, the simulations calculated all the forces in the T. rex’s limb bones, and then produced an estimate of the bone loading on impact. 
 
 Results indicated that any running gaits for T. rex would have undoubtedly led to “unacceptably high skeletal loads.” In other words, any kind of running would have broken this dinosaur’s legs. 
 
 “The available herbivorous dinosaurs in its environment...were all much slower than an adult T. rex—it was just slaughter in the slow lane.” 
 
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 “I think this is an important contribution because the modeling is based directly on the intrinsic limits of physical properties of bone, which quickly circumscribes the types of forces that such large skeletons could tolerate,” Thomas Carr, a paleontologist at Carthage College in Kenosha, Wisconsin, told Gizmodo. “In this case, running is eliminated for T. rex because the loads would simply snap the bones; this inference is consistent with previous work, and it is encouraging that different studies are converging on the same answer.” 
 
 The new findings suggest that T. rex couldn’t pursue its prey in a high speed chase, and that it led a less athletic life than previously assumed. But it was still a predator to be feared. 
 
 “It doesn’t matter if adult T. rex couldn’t run: all it had to do was move more quickly than its prey,” explained Carr, who wasn’t involved in the new study. “The available herbivorous dinosaurs in its environment—Edmontosaurus, Triceratops, Ankylosaurus—were all much slower than an adult T. rex— it was just slaughter in the slow lane.” 
 
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 David A. Burnham, a paleontologist at the University Kansas, says this study doesn’t show the whole picture. 
 
 “I would like to see a similar analysis done for Edmontosaurus and Triceratops,” he told Gizmodo. “If the data fits with these [animals] as prey items then we have a reasonable picture. In other words, the speed of T. rex should overlap theirs—at least for the young, slow and sick individuals since we know they were hunted.” 
 
 Burnham says the authors relied on a basic assumption about T. rex’s running style, and that, without knowing the “precise concert of the skeletomusculature system,” it could very well be that T. rex utilized a different gait similar to fast walking. 
 
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 This latest finding also holds implications for other large bipedal carnivores, such as Giganotosaurus, Mapusaurus, and Acrocanthosaurus. Sellers says these large animals may have been bound by similar physical constraints, but that further research will have to bear this assumption out. 
 
 
 
 [PeerJ] ||||| LONDON (Reuters) - Line up Usain Bolt at the starting blocks with a Tyrannosaurus rex and the dinosaur would be left behind in the sprinter’s dust, according to computer-assisted research that turns long-held assumptions on their head. 
 
 While the running ability of T-rex has been hotly debated among palaeontologists for decades, the consensus from previous biomechanical models was that the Cretaceous-era carnivore could manage speeds of up to 45 mph (75 kmh). 
 
 That’s more than half as fast again as the quickest man in history. 
 
 But because of its size and weight, the predator would actually have broken its legs had it tried to break into a sprint, the University of Manchester research showed. 
 
 “The muscles need to be able to generate sufficient power to allow high-speed locomotion, but at the same time the skeleton has to be able to cope with the loads generated by the high speed,” said Professor William Sellers from the university’s School of Earth and Environmental Sciences 
 
 “...This is where it fails. T-rex’s skeleton is simply not strong enough for running locomotion,” he told Reuters. 
 
 Researchers used an engineering technique called multibody dynamic analysis, coupled with machine learning, to produce what they say is the most accurate simulation of T-rex’s gait and biomechanics to date. 
 
 They concluded that T-rex was limited to walking speeds of about 5 meters/second, equating to 12 mph (18 kmh) — less than half the speed of Usain Bolt’s personal best of 27.8 mph. 
 
 A study published in Royal Society journal Biological Sciences in 2007 suggested an at that time conservative top speed of 18 mph - still fast enough to chase down top runners over longer distances. 
 
 Sellers said his study had forced a re-think on how T-rex caught its prey. 
 
 “It certainly would not have been able to chase down faster-moving prey animals,” said Sellers. “That leaves other hunting options such as ambush, and of course it means that (discredited) ideas such as ‘T-rex the scavenger’ have to be reconsidered.” ||||| Image copyright Getty Images Image caption T. rex was a fierce carnivore 
 
 The size and weight of a T. rex would have prevented it from moving faster than 20km/h (12mph), research suggests. 
 
 University of Manchester scientists used a new computer simulation to assess the speed of the massive biped. 
 
 Based on T. rex's muscles alone, the model came up with a maximum speed of 30km/h, but this dropped to 20km/h when skeletal strength was assessed too. 
 
 Had it moved from a brisk walk to a sprint, the dinosaur's legs would have snapped under the weight of its body. 
 
 "T. rex is everyone's favourite dinosaur, and palaeontologists have been arguing for years about how fast it could run because this would tell us something about its hunting style and the way it caught its prey,'' said Prof William Sellers. 
 
 ''This project used a highly realistic computer simulation to predict how T. rex moved, and it shows that running would have been impossible because its skeleton just isn't strong enough. 
 
 ''That means that T. rex was actually quite slow and therefore not a pursuit predator.'' 
 
 Hollywood makeover 
 
 Fossil footprints had already hinted that the mighty dinosaur was not as agile as its Hollywood image suggests. 
 
 However, Dr Eric Snively, of UW-La Crosse, US, who was not involved in the research, said it would still have been a scary creature. 
 
 The top speeds calculated for T. rex ''are still beyond those of most fast human joggers or distance runners and would be rather frightening to behold'', he said. 
 
 Referring to a scene in the sci-fi film, he added: ''It might well have caught Jeff Goldblum in Jurassic Park, had he stayed outside the Jeep and in the slippery mud.'' 
 
 Image copyright University of Manchester Image caption The research used sophisticated methods and tremendous computing power to calculate speeds 
 
 Prof Sellers said: "We can basically say that running was unlikely in any of the big predatory dinosaurs, but that doesn't mean that the smaller ones were not fast. 
 
 "That means that as it grows up, T. rex would get larger and slower and we would expect to see the hunting behaviour change. 
 
 "This really helps fill out the picture of what life was like in the cretaceous [period], when we have large numbers of dinosaurs roaming around." 
 
 The study is published in the journal Peer J. 
 
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– Jurassic Park had us all fooled: Outstripping a Tyrannosaurus rex in a Jeep would've been easy-peasy because, well, T. rex couldn't run. After much debate about how fast T. rex moved—previous estimates suggested up to 45 miles per hour—scientists at the University of Manchester used advanced computer simulations to come up with the most accurate assessment yet. Taking into account the beast's muscles and skeleton, they discovered running would've been "impossible" without a T. rex's legs buckling under its 7-ton weight, per the BBC. Study author William Sellers says T. rex instead walked at a pace of up to 12 miles per hour—a fast jog for humans and less than half of Usain Bolt's top speed of 27.8mph, report Reuters and Buzzfeed. As a researcher not involved in the study tells National Geographic, there's "no way T. rex could have chased down that Jeep in Jurassic Park if it was going at highway speeds. Maybe if it was in first gear, but even that's a big if." While it's a welcome discovery for anyone who might find themselves transported back in time, it also provides insight into how T. rex hunted. Juveniles may have been faster moving, but an adult T. rex "certainly would not have been able to chase down faster-moving prey animals," Sellers says. That means T. rex might have hid in forested areas and launched ambush attacks, or it might have dined mostly on slow-moving dinosaurs like Triceratops, reports Gizmodo. (T. rex sure had a nasty bite.)