That was one of Louis Agassiz’s problems with it, resolved of course by ridiculing and sidelining Agassiz (right).
Why, he [Agassiz] asked, does the fossil record always happen to be incomplete at the nodes connecting major branches of Darwin’s tree of life, but rarely—in the parlance of modern paleontology—at the “terminal branches” representing the major already known groups of organisms? These terminal branches were well represented (see Fig, 1.8), often stretching over many generations and millions of years, while the “internal branches” at the connecting nodes on Darwin’s tree of life were nearly always—and selectively—absent. As Agassiz explained, Darwin’s theory “rests partly upon the assumption that, in the succession of ages, just those transition types have dropped out from the geological record which would have proved the Darwinian conclusions had these types been preserved.” To Agassiz, it sounded like a just-so story, one that explains away the absence of evidence rather than genuinely explaining the evidence we have.
Was there any easy answer to Agassiz’s argument? If so, beyond his stated willingness to wait for future fossil discoveries, Darwin didn’t offer one. (p. 24)
And no one else has either. Here we are on the windy hilltop without one. Do we help keep the spin going? Or reassess how evolution works?
See also: Steve Meyer vs. hostile reviewer Charles Marshall