The male calf was born on Tuesday June 5 and is Rio and Marmaduke's first calf together.
Rio is a first-time mum. Marmaduke, however, has fathered 17 calves to date.
Dublin Zoo team leader Eddie O'Brien said: "We are delighted with the birth of the tapir calf. Mum and calf are doing very well, and we are really happy with how well Rio is doing as a first-time mum. The calf was up and about quickly after he was born - he is really inquisitive!"