Feces and vomit fossils offer evidence explaining dinosaur supremacy

This illustration provided by Marcin Ambrozik shows plant-eating dinosaurs in Poland during the Early Jurassic period. This undated photo provided by Grzegorz Niedzwiedzki shows fossilized plant-eating dinosaur feces found in the Holy Cross Mountains, Poland.

The way the dinosaurs relinquished their long dominance is well known. An asteroid struck Earth 66 million years ago, triggering a horrific mass extinction. But the way the dinosaurs -- modest creatures initially -- came to supremacy is less well understood.