The largest dinosaurs in each major group, now including Amphicoelias!! … I had to cheat to fit it in there! All sizes are estimated based on close relatives.
Ceratopsipes-12.1 meters/~18 tons
Spinosaurus-16- meters/10-12 tons
Giant Utah Nodosaur-9 meters/7-8 tons
Dacentrurus-9.5 meters/7-9 tons
Amphicoelias~60+ meters/125+ tons (Assuming Diplodocid proportions)
Now much improved layout, and with an updated Spinosaurus, Dacentrurus and Amphicoelias.