The most obvious difference between the brains of mammals and other vertebrates is in terms of size. On average, a mammal has a brain roughly twice as large as that of a bird of the same body size, and ten times as large as that of a reptile of the same body size.
Is there an answer to this question (If it cannot be answered, say "unanswerable"): The biggest difference between brains of mammals and other vertebrates is what?
size.