Can a lion and an elephant, two different mammal species, communicate with each other?
To a limited extent. An elephant can understand threat from a lion and a lion can understand do not mess with me I am too big.
By body language and sounds, yes. "keep away" "I'm nervous" etc.
The First Dragon
Yes they can, but normally they don't have a lot to say to each other. But they are both capable of threatening the other for instance, or of not threatening and being more tolerant. They are not likely to get into a fight though, because both would get hurt and neither could really gain anything.
Different animals communicate all the time. The lion says "You look tasty." The antelope says "See Ya"
i dont see why not