The real problem, one for which YE creationism has no adequate explanation, is the fossil record of cetaceans (whales and their kin):
"At this point in time, the largest challenge from the stratomorphic intermediate record appears to this author to come from the fossil record of the whales. There is a strong stratigraphic series of archaeocete genera claimed by Gingerich60(Ambulocetus, Rhodocetus, and Prozeuglodon[or the similar-aged Basilosaurus]61) followed on the one hand by modern mysticetes,62 and on the other hand by the family Squalodontidae and then modern odontocetes.63 That same series is also a morphological series: Ambulocetuswith the largest hind legs;64-66 Rhodocetus with hindlegs one- third smaller;67Prozeuglodon with 6 inch hindlegs;68 and the remaining whales with virtually no to no hind legs: toothed mysticetes before non-toothed baleen whales;69 the squalodontid odontocetes with telescoped skull but triangular teeth;70 and the modern odontocetes with telescoped skulls and conical teeth. This series of fossils is thus a very powerful stratomorphic series. Because the land mammal-to-whale transition (theorized by macroevolutionary theory and evidenced by the fossil record) is a land-to-sea transition, the relative order of land mammals, archaeocetes, and modern whales is not explainable in the conventional Flood geology method (transgressing Flood waters). Furthermore, whale fossils are only known in Cenozoic (and thus post-Flood) sediments.71 This seems to run counter to the intuitive expectation that the whales should have been found in or even throughout Flood sediments.At present creation theory has no good explanation for the fossil record of whales. "
YE creationist Kurt Wise, Towards a CreationistUnderstanding ofTransitional Forms