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Paleontologists think that Tyrannosaurus, Sauroposeidon, and other long-extinct theropods and sauropods may have breathed using air sacs connected to tubelike extensions inside the animals' bones. Such structures are found in modern birds, which is why some paleontologists treat the respiratory systems of birds as _____ those of Tyrannosaurus, Sauroposeidon, and other theropods and sauropods.