The appearance of "The Origin of Species" in 1859 revolutionised all the biological sciences. From the very nature of the case, Darwin was compelled to give careful consideration to the palaeontological evidence; indeed, it was the palaeontology and modern distribution of animals in South America which first led him to reflect upon the great problem. In his own words: "I had been deeply impressed by discovering in the Pampean formation great fossil animals covered with armour like that on the existing armadillos; secondly, by the manner in which closely allied animals replace one another in proceeding southward over the Continent; and thirdly, by the South American character of most of the productions of the Galapagos archipelago, and more especially by the manner in which they differ slightly on each island of the group." ("Life and Letters of Charles Darwin", I. page 82.) In the famous tenth and eleventh chapters of the "Origin", the palaeontological evidence is examined at length and the imperfection of the geological record is strongly emphasised. The conclusion is reached, that, in view of this extreme imperfection, palaeontology could not reasonably be expected to yield complete and convincing proof of the evolutionary theory. "I look at the geological record as a history of the world imperfectly kept, and written in a changing dialect; of this history we possess the last volume alone, relating only to two or three countries. Of this volume, only here and there a short chapter has been preserved; and of each page, only here and there a few lines." ("Origin of Species", page 289.) Yet, aside from these inevitable difficulties, he concludes, that "the other great leading facts in palaeontology agree admirably with the theory of descent with modification through variation and natural selection." (Ibid. page 313.) Darwin's theory gave an entirely new significance and importance to palaeontology. Cuvier's conception of the science had been a limited, though a lofty one. "How glorious it would be if we could arrange the organised products of the universe in their chronological order!... The chronological succession of organised forms, the exact determination of those types which appeared first, the simultaneous origin of certain species and their gradual decay, would perhaps teach us as much about the mysteries of organisation as we can possibly learn through experiments with living organisms." (Zittel op. cit. page 140.) This, however, was rather the expression of a hope for the distant future than an account of what was attainable, and in practice the science remained almost purely descriptive, until Darwin gave it a new standpoint, new problems and an altogether fresh interest and charm. The revolution thus accomplished is comparable only to that produced by the Copernican astronomy.