I've noticed that unique things about Spinosaurus include thoracic and caudal vertebrae that are about twice as long as on other theropods. This extended vertebral column adds a huge amount to the length of the animal. It was a laterally thin animal, and had a shallower rib cage, like compsognathids and dilophosaurs. In that case, a Spinosaurus would be quite light for an animal of it's length. So even with it being 50 feet excess, it still would have been quite "light" wouldn't it? It was clearly a gigantic but oddly light animal! So prehaps I'm not to sure length is a good size or weight estimate. I mean Tyrannosaurids have massively built bodies but slighter tails, so they would have been much heavier than animals their length. (Like A.Fragilis or Maximus).
from Leonard, age 14, ?, ?, ?; July 28, 2001

TOM: Because Spinosaurus itself is not known from a complete skeleton, I am not certain where you are getting your proportions. Look at Suchomimus for the most complete spinosaurid body known, then scale up from there.