Understanding the relationship between created kinds and Ark kinds is a key issue in creation science, especially as it has bearing on the Flood/post-Flood boundary debate. This paper first considers whether there is classification terminology in the Old Testament that represents the creationist concept of the baramin. Then, three possible ways Ark kinds could relate to the created kinds are evaluated with biostratigraphic data. Evidence from the fossil record narrows the possible understanding of Ark kinds, shedding light on challenges in the Flood/post-Flood boundary debate.