When I saw Godzilla a few years ago (the new one, based in New York), as we left the theatre, I commented to a friend on the physical improbability of it. The beast was made out of flesh and bone, yet when it brushed skyscrapers as it ran through the canyons of New York City, it tore off huge chunks of concrete and steel from them, with no apparent damage to its own body.

But even more of a problem is the thermodynamics. When you consider how much power it would take to move that much mass at those speeds, and then consider how large the body was, with a very high mass-to-surface-area ratio, it seems impossible to cool it. The thing would basically cook from the inside out.

This is one of the limits on the size of warm-blooded animals, particularly if they’re very active. We now believe that dinosaurs were warm blooded, but we have no reason to believe that they moved particularly fast, at least, not the large ones like apatasaurus.

Anyway, den Beste has a similar, and entertaining, series of posts about an upcoming movie featuring fire-breathing dragons, and how they’d be no match for modern weaponry.