Student or Learner
Since animals lose body heat through surfaces, a higher surface-to-volume ratio would result in greater loss of body heat. This is ① why smaller animals lose more body heat. As a result, a mouse or a hummingbird must burn a lot of calories to maintain a constant body temperature. This is the main reason ② that, among warm-blooded animals, metabolic rate declines with increasing body size. Small mammals have evolved to produce relatively more body heat. Their faster metabolic rate means ③ what they do not live as long. Small animals tend to have shorter lives than large animals, and warm-blooded animals shorter lives than cold-blooded animals. Conversely, large animals can have warm bodies just ④ because they are large. Large dinosaurs, for example, were probably warm-blooded simply ⑤ because of their low surface-to-volume ratio.
The two underlined sentences seem to be contradictory. The writer says "warm-blooded animals have shorter lives" at first, and says "large animals with warm bodies such as dinosaurs lived longer". Did the writer make a mistake?
Where does it say that warm bodied dinosaurs lived longer?
You also need to make sure you are comparing the same thing. Lived longer than what? Cold bodied dinosaurs? Small dinosaurs? Warm bodied mammals? etc.