Actually, superstitious pseudo mysticism incorporated in to Biology a century ago that still hangs on.
The fetus visibly passes through these stages, just as the brain develops from a reptilian base to mammalian. I've seen pictures of this 40 and more years ago.
The part of the article that is idiotic, and I guess the basis of the "new study," is the attempt to compare fetal development to specific prehistoric fossils. There is no need and no ability to make such a specific comparison.