Top 10 Fastest Dinosaurs

The Usain Bolt of the dinosaur era has been identified, along with nine of the other fastest dinosaurs that ever lived.

Many dinosaurs had a need for speed, according to new research that is helping paleontologists figure out how fast, or slow, dinos once moved.

The findings, published in the journal Scientific Reports, show that to run faster, certain dinosaurs evolved longer legs. Concavenator certainly fits that model, and ranks 10th in dinosaur speed.

"Nicknamed the 'Cretaceous camel,' this bizarre humpbacked dinosaur has no shortage of strange anatomy, including its legs," Scott Persons, who led the study, told Discovery News.

"Concavenator has the long legs of a sprinter and also very tiny feet that suggest it may have pursued its prey only over firm dry ground," added Persons, who is a University of Alberta paleontologist. "Concavenator's great weight combined with its little toes might have made it prone to becoming mired if it tried to run across the soft soil of a marsh or swamp."

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For the study, Persons and co-author Philip Currie spent years collecting leg measurements from more than 50 different species of predatory dinosaurs from museum collections around the world. The dinosaurs ranged in size from being smaller than a chicken to being longer than a school bus.

The researchers used the data to develop an equation to determine a dinosaur's "cursorial limb proportion score," a measure of how strongly adapted for speed a particular dino species was. Each dinosaur's requirements for weight support were also taken into account.

As Persons explained, "You cannot just compare little dinosaurs to big dinosaurs; you have to factor out the influence of body mass."

Coming in at number nine is the South American predator Carnotaurus, which actually looked like a real speed demon, given that it was adorned with two devilish horns.

"Like all non-avian dinosaurs, it had a large muscle in its tail that was anchored to its thigh and provided extra power to its legs," Persons said. "But the skeletal anatomy of Carnotaurus' tail indicates that this muscle was supersized and so too was the locomotive power it provided."

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The authors pointed out that the relationship between speed and leg length is a general anatomical rule seen today in living animals. Cheetahs are faster and have proportionately longer legs than lions, which are faster and have proportionately longer legs than hyenas.

Deltadromeus, if it were still alive today, could have run down such modern animals. Its name means "Delta Runner," and analysis of its long legs indicates it lived up to this title.

"Racing across the costliness and floodplains of prehistoric Egypt, Deltadromeus was the fastest dinosaur in its ecosystem," Persons explained. "It probably needed to be, because it shared its environment with much larger, but slower, carnivores like the enormous Spinosaurus and Carcharodontosaurus."

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The "Jurassic Park" franchise needs some revising, especially when it comes to its scaly stars the velociraptors.

"Contrary to popular depiction, the dromaeosaurs, like the famous Velociraptor, were not highly adapted for speed, but the same cannot be said for their sickle-clawed cousins the troodontids," Persons said. "About the same size as Velociraptor, Troodon could have run circles around the 'Jurassic Park' star."

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Although we think of tyrannosaurs as the kings of dinosaurs, the group did not begin that way.

"Early wolf-sized tyrannosauroids, like Guanlong were both hunters and hunted," Persons said. "But they did start out fast. Speed was important to tyrannosauroids, as it let them both catch prey that other predators could not and also helped them to avoid being caught themselves."

David Evans of the Royal Ontario Museum has also considered dinosaurs' speediness, or lack thereof. In earlier work published in the Journal of Vertebrate Paleontology, Evans and his team speculated that fused lower leg bones could have enhanced running speed and agility in dinosaurs.

Evans and his colleagues recently discovered tiny plant-eating Albertadromeus syntarsus, which had such fused leg fossils. This scrappy dino was about the size of a modern turkey and appears to have been prey for many larger carnivorous species. Time will tell if it might push into this top 10 list as more is learned about the dino, whose name means "Alberta runner with fused foot bones."

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Just how fast the mighty T. rex could move is the subject of intense debate, but the researchers believe that it was speedy enough to land in the number five spot on this list.

"Tyrannosaurus has much longer legs than its fellow carnivorous heavyweights, like Allosaurus or Giganotosaurus, and it also has a specially adapted ankle and foot capable of absorbing the shock and springing back from high-speed impacts with the ground," Persons said.

"Other scientists would bet against me," he continued, "but at the dino racetrack, I think the smart money is usually on T. rex."

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More lightly built than T. rex and with proportionately longer legs, Gorgosaurus was a tyrannosaur with an even greater investment in speed.

The researchers added that, like most of the other dinosaurs on this list, Gorgosaurus could maintain a fast spring for only a short time since it was adapted for limited bursts of speed.

"Some herbivorous dinosaurs, like the duckbills, may have exploited this by adapting, not for speed, but for endurance," Persons said.

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Preserved stomach contents from this seven-foot-long dinosaur show that it preyed on early birds and small raptor dinosaurs.

"To catch such food, Sinocalliopteryx probably had to employ a combination of a stealth approach and a swift lunge," Persons said.

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Another troodontid and a close relative of birds, Sinornithoides was the roadrunner of the dinosaur world. Like a bird, it relied far less on the muscle power of its tail to help it run. To compensate for its reduced tail musculature, it had altered its center of gravity and limb mechanics.

"Zooming through Cretaceous China and Mongolia, Sinornithoides would have chased after small lizards, insects, and our own ancient mammalian relatives," Persons said.

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The researchers concluded that Nanotyrannus was the Usain Bolt of its era.

Persons said, "Of all the dinosaurs, Nanotyrannus is the one that I would least like to be chased by. Taking the characteristically long legs of tyrannosaurs to the extreme, Nanotyrannus had the stride to leave all other big carnivores in the dust."

Living alongside T. rex, Nanotyrannus may be an example of the evolutionary and ecological phenomenon known as niche partitioning. That means it may have become specialized to run down the smaller and quicker prey that T. rex could not catch. As a result, it could have avoided direct competition with its bigger relative.

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