total of 30 teeth; the dental formula is . The sharp, narrow carnassials are larger than those of leopards and lions, suggesting the cheetah can consume larger amount of food in a given time period. The small, flat canines are used to bite the throat and suffocate the prey. A study gave the bite force quotient (BFQ) of the cheetah as 119, close to that for the lion (112), suggesting that adaptations for a lighter skull may not have reduced the power of the cheetah's bite. Unlike other cats, the cheetah's canines have no gap behind them when the jaws close, as the top and bottom cheek teeth show extensive overlap; this equips the upper and lower teeth to effectively tear through the meat. The slightly curved claws, shorter and straighter than those of other cats, lack a protective sheath and are partly retractable. The claws are blunt due to lack of protection, but the large and strongly curved dewclaw is remarkably sharp. Cheetahs have a high concentration of nerve cells arranged in a band in the centre of the eyes, a visual streak, the most efficient among felids. This significantly sharpens the vision and enables the cheetah to swiftly locate prey against the horizon. The cheetah is unable to roar due to the presence of a sharp-edged vocal fold within the larynx. Speed and acceleration The cheetah is the world's fastest land animal. Estimates of the maximum speed attained range from . A commonly quoted value is , recorded in 1957, but this measurement is disputed. In 2012, an 11-year-old cheetah (named Sarah) from the Cincinnati Zoo set a world record by running in 5.95 seconds over a set run, recording a maximum speed of . Contrary to the common belief that cheetahs hunt by simply chasing its prey at high speeds, the findings of two studies in 2013 observing hunting cheetahs using GPS collars show that cheetahs hunt at speeds much lower than the highest recorded for them during most of the chase, interspersed with a few short bursts (lasting only seconds) when they attain peak speeds. In one of the studies, the average speed recorded during the high speed phase was , or within the range including error. The highest recorded value was . The researchers suggested that a hunt consists of two phases—an initial fast acceleration phase when the cheetah tries to catch up with the