Spinosauridae size chart. From the largest to the smallest: Spinosaurus, Oxalaia, Suchomimus, Baryonyx, Ichthyovenator and Irritator. Remake of this: [link]
Spino probably didn't have legs that long, but in any case, it was only vaguely a land carnivore, and almost definitely weighed less than, for example, large suchians, which are often estimated at 8 or 9 tonnes or so.
