> My understanding is that a species' maximum speed depends simply on muscle mass If so, that doesn’t mean that they would get faster if only they got more mus

> My understanding is that a species' maximum speed depends simply on muscle mass If so, that doesn’t mean that they would get faster if only they got more muscle. I would expect that species evolve towards not having more muscle than they can effectively use. I think looking at elite human runners supports that. At longer distances, they get less muscular. > The reason elephants don't outrun cheetahs is that they […] run out of energy before hitting the top speed their muscles could produce. > Look up allometry for more. There are formulas for calculating top speed based on mass. I think our best knowledge is that adding more muscle only works for a limited time. https://news.cgtn.com/news/3d51544f7767444e/share.html https://news.cgtn.com/news/3d51544f7767444e/share.html: “If muscles were all that mattered "elephants would reach maximum speeds of about 600 kph (370 mph)," she told AFP. Instead, tuskers peak at about 34 kph (21 mph). Big beasts, in other words, run out of so-called anaerobic energy, supplied by the muscles, before being able to reach their theoretically maximum speed.“