It is a good question but it still does not patch any of the giant holes in the TOE.
...in the seventeenth century [1644], in his great work, Dr. John Lightfoot, Vice-Chancellor of the University of Cambridge, and one of the most eminent Hebrew scholars of his time, declared, as the result of his most profound and exhaustive study of the Scriptures, that "heaven and earth, centre and circumference, were created all together, in the same instant, and clouds full of water," and that "this work took place and man was created by the Trinity on October 23, 4004 B.C., at nine o'clock in the morning."Andrew D. White, A History of the Warfare of Science with Theology in Christendom (D. Appleton and Co., 1897, p. 9).
The only answer I've ever seen is that what we consider "modern" animals were merely the created kinds that were smarter or faster runners as they sought higher ground during the Flood. Or that the "modern" animals were less dense, so they floated to the top of the sediments as the churned-up muddy waters precipitated out, while the more "primitive" animals were merely the ones that had the denser bodies. Or something along those lines.