Not sure what your comment has to do with mine. That doesn't mean the total available biomass to predators in aggregate was larger or smaller, just because some

Not sure what your comment has to do with mine. That doesn't mean the total available biomass to predators in aggregate was larger or smaller, just because some big dinosaurs existed. It doesn't even mean T-rex hunted brontosaurus frequently or at all (given the somewhat different eras), much like the modern lions don't really hunt adult elephants.