Top 5 Fastest Dinosaurs

Concavenator attacking another dinosaur, Pelecanimimus.

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."

Carnotaurus

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."

Deltadromeus

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."

Guanlong

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."