Passage Summary: Because dinosaurs had consistent body heat from head to toe—unlike today's cold-blooded creatures—scientists believe they must have been warm-blooded.

Conclusion: Dinosaurs were likely warm-blooded animals.

Reasoning: Dinosaur fossils show uniform body temperatures across their limbs and core, whereas modern cold-blooded animals have significantly higher temperatures in their cores than in their limbs.

Analysis: The argument relies on the assumption that uniform body temperature is a trait exclusive to warm-blooded creatures. To weaken this, we need to find a scenario where a cold-blooded animal could also maintain a consistent temperature throughout its body. Perhaps the environment the dinosaurs lived in was so warm and stable that their limbs never had the chance to cool down. Look for an answer that provides an alternative explanation for the uniform isotope distribution that doesn't require the dinosaurs to be warm-blooded.