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Re: hadrosaurs outgrew tyrannosaurs

I've just read the paper, and I think there's a simple logical error.

The authors write two critical sentences

1. Life-history theory suggests that prey species should experience rapid growth if juvenile mortality (caused mainly by predation) is high and resources are plentiful (or readily available) (Arendt & Reznick 2005).

2. ..we predict that Hypacrosaurus grew faster and matured sooner than coeval theropods.

Sentence 1 is, I presume, a fair summary of a *theoretical* model.

Sentence 2 is an unwarranted prediction from that model. The model suggests only that prey should grow fast if they can. It does NOT say that they should grow faster than their predators.

The authors make a great flag-waving display of the result that they find: that the hadrosaur grew faster than *one* of its potential predators. I am surely not so cynical as to think that this apparent fulfilment of their (faulty) prediction was a contrived ploy to get publicity. It wasn't in the title of their paper, for example. But it's clearly been given great play by the reporters at National Geographic and elsewhere.

So where are we? The authors show unambiguously that this hadrosaur species grew fast, considerably faster than a contemporary predator. The fast growth is impressive in itself. But it's not the smash hit that the commentators suggest!


Richard Cowen