That's one of the things that always gets me about dinosaurs - the sheer range of sizes. The longest dinosaur discovered so far (though only reconstructed from one vertebra) is a sauropod called Amphicoelias which may have been up to 60m long. I can't even visualise that in my head, wiki has a size comparison thing which is just incredible:
http://en.wikipedia.org/wiki/Image:H...comparison.png
can you imagine looking one in the eye?? What happened when one of those died, how long did it take before there was nothing left of it? Imagine the smell