I have good news and bad news today - the bad news is this is not the post where you get an estimate of the mass of Spinosaurus. I know, I know. And I'm sorry. Here's the good news: in preparation for a deeper look at the challenges of estimating the mass of Spinosaurus, I've produced far more rigorous mass estimates of Tyrannosaurus and Giganotosaurus from GDI, and I got some surprising results to share.

First, a word on that Spinosaurus post - I've heard from several of you that there is a degree of anticipation for it, and I apologize for the delay. That said, you're going to get a much better post in exchange for your patience. My original intention had been to do a more generic look at scaling up different types of theropods to the length of Spinsosaurus, which would not have been very precise. Even worse, since it would have relied on other people's mass estimates it would have been comparing mass estimates derived from different methodologies, which threatened to make the whole process an act of futility.

Instead you will be getting mass estimates I've generated directly from my own skeletal reconstructions. The mass estimates I'm sharing today were produced using Graphic Double Integration (GDI), a technique that lets you estimate the volume of complex 3D objects by averaging many cross-sections together. If you are unfamiliar with the process, you can think of it as taking a balloon animal and using math to average it into a more normal oval-shaped balloon of the same volume to make it easier to measure. I won't go into detail on how to perform a GDI analysis, because the SV-POW team has already written up a really good tutorial here, which you should definitely read if you want to do your own GDI analysis.

First: the reveal: