[acurro]

Great article!

I have a question not related to reef tanks, for once. If the trophic levels as they exist now do so because the number of primary producers can only support so many predators, why were animals so much larger several millions of years ago? Dinosaurs are so much larger than modern elephants, sharks were larger, even mammouths existed in cold environments. Icythyosaurus, for example, existed eating fish. Was primary production larger then? I have three thoughts, I am not sure if any are correct:

1) So many nutrients have become locked beneath thermoclines over the ages that there are decreasing number of nutrients to fuel primary production.

2) There was more carbon dioxide in the atmosphere then, fueling primary production.

3) Biological dice rolling!