Phyletic gradualism

The word phyletic derives from the Greek φυλετικός phūletikos, which conveys the meaning of a line of descent.

[2] Phyletic gradualism contrasts with the theory of punctuated equilibrium, which proposes that most evolution occurs isolated in rare episodes of rapid evolution, when a single species splits into two distinct species, followed by a long period of stasis or non-change.

[3][4] Evolutionary biologist Richard Dawkins argues that constant-rate gradualism is not present in the professional literature, thereby the term serves only as a straw-man for punctuated-equilibrium advocates.

In his book The Blind Watchmaker, Dawkins observes that Charles Darwin himself was not a constant-rate gradualist, as suggested by Niles Eldredge and Stephen Jay Gould.

In the oldest tertiary beds a few living shells may still be found in the midst of a multitude of extinct forms...

Phyletic gradualism, top, would consist of steady evolutionary change in small steps, in contrast to punctuated equilibrium
Apparently sudden changes can be explained either by macromutation or by relatively rapid episodes of gradual evolution, since 10,000 years barely registers in the fossil record.