[High Praise! to Mental Floss]
Why Were Dinosaurs So Large and Why Don’t Animals of That Scale Exist Today?
[Think you have a link that’s IMAO-worthy? Send it to harvolson@gmail.com. If I use your link, you will receive High Praise! (assuming you remember to put your name in the email)]

I don’t know, you’ve seen those pictures from the last NOW meeting?
YANG/BETO 2020!
I figure it’s because the atmosphere was thicker then so it could support larger organisms.
The asteroid that hit back then displaced a lot of air into space thinning the atmosphere and burning up lots of oxygen putting more CO2 into the depleted atmosphere.
So to answer Homer Simpson’s question, that’s why we have an Air in Space Museum in DC.