Does anyone have any info on the actual size of a dinosaur's lung or rib cage for a given species? There are plenty of pictures, but I haven't found much data (with numbers!) on measurements of a lung or rib cage.

You would need to be a little more specific. Your question is just like saying what is the rib cage size of a dog? Well there is a big difference between a poodle and a St. Bernard, but they are both dogs. What kind of dino?

Yes, it would be helpful to know which specific dinosaur it is to which you are referring.

Right now, because I haven't found any info, any dinosaur would be good! However, the tyranessaurus, triceratops and/or stegosaurus would be great!

Well, it might vary, but a triceratop dubbed "Kelsey" has a chest size of 73 in or (185 cm). You can find additional information here (http://www.bhigr.com/store/product.php?productid=400).

For an example of a tyrannosaurus, this one is named "Bucky". Chest size measured at 56 in and 142 cm. Site is here (http://www.bhigr.com/store/product.php?productid=398).

Stegosaurus, some studies estimated it to be about 49 in. or 125 cm to 60 in or 150 cm. Source is the Dinosauria book that has publications of research studies on dinosaurs. Hopefully these help you!

I just want to say that these are estimates and sizes taken from dinosaurs that had nearly complete skeletons. It does not account for all dinosaurs, because we can only estimate the size of some, and it's very hard to find complete skeletons. Sometimes we get lucky and sometimes we only find rib fragments that don't offer so much information.