You're right that big dinosaurs only lost because they were big, not because they were an evolutionary dead end of some sort. From an anthropocentric point of

You're right that big dinosaurs only lost because they were big, not because they were an evolutionary dead end of some sort. From an anthropocentric point of view, though, they seem very dead end. Despite bipedalism and possible warm bloodedness sometimes, they would never use tools. Down so many taxonomic branches, their arms would shrink away and their jaws become enormous. Nothing to motivate any of those lizards to get big brains -- something anthropos value highly :)