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Postcranial skeletal pneumaticity (PSP) refers to the presence of extensions of an animal’s lungs and air sacs inside its bones. Though such structures do not typically fossilize, they are believed to have been present in Tyrannosaurus, Euhelopus, and other Cretaceous theropods and sauropods. To _______ PSP from fossils, researchers look for indicators such as large foramina (holes in bones).