“Paleontologists had long been aware of a seeming contradiction between Darwin‘s postulate of gradualism, confirmed by the work of population genetics, and the actual findings of paleontology. Following phyletic lines through time seemed to reveal only minimal gradual changes but no clear evidence for any change of a species into a different genus or for the gradual origin of an evolutionary novelty. Anything truly novel always seemed to appear quite abruptly in the fossil record.”
Ernst Mayr, “Toward a New Philosophy of Biology: Observations of an Evolutionist,” Harvard University Press: Cambridge MA, 1988, pp. 529-530.
Note: Ernst Mayr was one of the 20th century’s leading evolutionary biologists. He was also a renowned taxonomist, tropical explorer, ornithologist, historian of science, and naturalist, and was Emeritus Professor of Zoology, Harvard University.