The evolutionist assertion is that each species on earth came from a single common ancestor through minor changes. In other words, the theory considers life as a continuous phenomenon, without any preordained or fixed categories. However, the observation of nature clearly does not reveal such a continuous picture. What emerges from the living world is that life forms are strictly separated in very distinct categories. Robert Carroll, an evolutionist authority, admits this fact in his Patterns and Processes of Vertebrate Evolution:

Although an almost incomprehensible number of species inhabit Earth today, they do not form a continuous spectrum of barely distinguishable intermediates. Instead, nearly all species can be recognized as belonging to a relatively limited number of clearly distinct major groups, with very few illustrating intermediate structures or ways of life.37

Therefore, evolutionists assume that "intermediate" life forms that constitute links between living organisms have lived in the past. This is why it is considered that the fundamental science that can shed light on the matter is paleontology, the science of the study of fossils. Evolution is alleged to be a process that took place in the past, and the only scientific source that can provide us with information on the history of life is fossil discoveries. The well-known French paleontologist Pierre-Paul Grassé has this to say on the subject:

Naturalists must remember that the process of evolution is revealed only through fossil forms... only paleontology can provide them with the evidence of evolution and reveal its course or mechanisms.38

The most important branch of science for shedding light on the origin of life on Earth is paleontology, the study of fossils. Fossil beds, studied with great intensity for the last two hundred years, reveal a picture totally at odds with Darwin's theory. Species did not emerge through small cumulative changes, they appeared quite suddenly, and fully-formed.

In order for the fossil record to shed any light on the subject, we shall have to compare the hypotheses of the theory of evolution with fossil discoveries.

According to the theory of evolution, every species has emerged from a predecessor. One species which existed previously turned into something else over time, and all species have come into being in this way. According to the theory, this transformation proceeds gradually over millions of years.

If this were the case, then innumerable intermediate species should have lived during the immense period of time when these transformations were supposedly occurring. For instance, there should have lived in the past some half-fish/half-reptile creatures which had acquired some reptilian traits in addition to the fish traits they already had. Or there should have existed some reptile/bird creatures, which had acquired some avian traits in addition to the reptilian traits they already possessed. Evolutionists refer to these imaginary creatures, which they believe to have lived in the past, as "transitional forms."

If such animals had really existed, there would have been millions, even billions, of them. More importantly, the remains of these creatures should be present in the fossil record. The number of these transitional forms should have been even greater than that of present animal species, and their remains should be found all over the world. In The Origin of Species, Darwin accepted this fact and explained:

If my theory be true, numberless intermediate varieties, linking most closely all of the species of the same group together must assuredly have existed... Consequently evidence of their former existence could be found only amongst fossil remains.39

Even Darwin himself was aware of the absence of such transitional forms. He hoped that they would be found in the future. Despite his optimism, he realized that these missing intermediate forms were the biggest stumbling-block for his theory. That is why he wrote the following in the chapter of the The Origin of Species entitled "Difficulties on Theory":

…Why, if species have descended from other species by fine gradations, do we not everywhere see innumerable transitional forms? Why is not all nature in confusion, instead of the species being, as we see them, well defined?… But, as by this theory innumerable transitional forms must have existed, why do we not find them embedded in countless numbers in the crust of the earth?… But in the intermediate region, having intermediate conditions of life, why do we not now find closely-linking intermediate varieties? This difficulty for a long time quite confounded me.40

The only explanation Darwin could come up with to counter this objection was the argument that the fossil record uncovered so far was inadequate. He asserted that when the fossil record had been studied in detail, the missing links would be found.

37 Robert L. Carroll, Patterns and Processes of Vertebrate Evolution, Cambridge University Press, 1997, p. 9
38 Pierre Grassé, Evolution of Living Organisms, Academic Press, New York, 1977, p. 82.
39 Charles Darwin, The Origin of Species: A Facsimile of the First Edition, Harvard University Press, 1964, p. 179.
40 Charles Darwin, The Origin of Species by Means of Natural Selection, The Modern Library, New York, p. 124-125. (emphasis added)