So apparently a number of experts recently got together to reexamine mega theropod size and weight estimates and the results are interesting to say the least. carcharodontosaurus and giganotosaurus were discovered to be more narrow and lightly built than previous estimates putting them both below 7 tonnes. Although I found that fascinating its nothing compared to poor Spino. The new estimates indicate it was closer to 5 tonnes and is no longer classified as a mega theropod, the new studies showing it was build much lighter than previously believed. The size estimates for Rex were relatively unchanged at 8.8 tonnes for sue. On a side note to this there was also a new study about agility which indicated that Trex was likely the most agile of all mego theropods.