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The BBC’s Science Focus website has an intriguing story about Tyrannosaurus rex.  Iintriguing and a bit disturbing… but “How many humans would a T. rex need to eat to stay alive?”

An adult Tyrannosaurus rex weighed about seven tonnes. A crocodile eats about five per cent of its body weight per week, whereas a warm-blooded predator, like a lion, needs to eat 25 per cent of its body weight each week. 

T. rex probably had a metabolism somewhere in between. So if we say 15 per cent, this would translate to more than a tonne of meat per week, or about two people a day.

In reality, apex predators normally have much less regular meals, so T. rex might starve for a month and then eat a busload of time-travelling tourists all at once.