If both of the given statements were true (which they are not), the third statement would NOT be logically true. Here is why:
From the two given statments, only PART of the third statement would be true. From the two given statements, we know that at least some mammals are animals. We cannot assume that ALL mammals are animals. But at least some are and so mammals can be animals.
However, the two given statements tell us explicitly that mammals have no tail. Therefore, there can be no such thing as a mammal with a tail. This part of the statement is not logically true.