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- The Antiquity of Man - 70/91 -

Professor Sedgwick's "Discourse on the Studies of the University of Cambridge" Preface to 5th edition pages 44, 154, 216, 1850.)

Although in the half century which has elapsed between the time of Lamarck and the publication of the above summary, new discoveries have caused geologists to assign a higher antiquity both to Man and the oldest fossil mammalia, fish, and reptiles than formerly, yet the generalisation, as laid down by the Woodwardian Professor, as to progression, still holds good in all essential particulars.

The progressive theory was propounded in the following terms by the late Hugh Miller in his "Footprints of the Creator."

"It is of itself an extraordinary fact without reference to other considerations, that the order adopted by Cuvier in his "Animal Kingdom," as that in which the four great classes of vertebrate animals, when marshalled according to their rank and standing, naturally range, should be also that in which they occur in order of time. The brain, which bears an average proportion to the spinal cord of not more than two to one, comes first--it is the brain of the fish; that which bears to the spinal cord an average proportion of two and a half to one succeeded it--it is the brain of the reptile; then came the brain averaging as three to one--it is that of the bird. Next in succession came the brain that averages as four to one--it is that of the mammal; and last of all there appeared a brain that averages as twenty-three to one--reasoning, calculating Man had come upon the scene."* (* "Footprints of the Creator" Edinburgh 1849 page 283.)

M. Agassiz, in his "Essay on Classification," has devoted a chapter to the "Parallelism between the Geological Succession of Animals and Plants and their present relative Standing;" in which he has expressed a decided opinion that within the limits of the orders of each great class there is a coincidence between their relative rank in organisation and the order of succession of their representatives in time.* (* "Contributions to the Natural History of the United States" Part 1.--Essay on Classification page 108.)

Professor Owen, in his Palaeontology, has advanced similar views, and has remarked, in regard to the vertebrata that there is much positive as well as negative evidence in support of the doctrine of an advance in the scale of being, from ancient to more modern geological periods. We observe, for example, in the Triassic, Oolitic, and Cretaceous strata, not only an absence of placental mammalia, but the presence of innumerable reptiles, some of large size, terrestrial and aquatic, herbivorous and predaceous, fitted to perform the functions now discharged by the mammalia.

The late Professor Bronn, of Heidelberg, after passing in review more than 24,000 fossil animals and plants, which he had classified and referred each to their geological position in his "Index Palaeontologicus," came to the conclusion that, in the course of time, there had been introduced into the earth more and more highly organised types of animal and vegetable life; the modern species being, on the whole, more specialised, i.e. having separate organs, or parts of the body, to perform different functions, which, in the earlier periods and in beings of simpler structure, were discharged in common by a single part or organ.

Professor Adolphe Brongniart, in an essay published in 1849 on the botanical classification and geological distribution of the genera of fossil plants,* (* Tableau des Genres de Vegetaux fossiles, etc. "Dictionnaire Universel d'Histoire Naturelle" Paris 1849.) arrives at similar results as to the progress of the vegetable world from the earliest periods to the present. He does not pretend to trace an exact historical series from the sea-weed to the fern, or from the fern again to the conifers and cycads, and lastly from those families to the palms and oaks, but he, nevertheless, points out that the cryptogamic forms, especially the acrogens, predominate among the fossils of the primary formations, the Carboniferous especially, while the gymnosperms or coniferous and cycadeous plants abound in all the strata, from the Trias to the Wealden inclusive; and lastly, the more highly developed angiosperms, both monocotyledonous and dicotyledonous, do not become abundant until the Tertiary period. It is a remarkable fact, as he justly observes, that the angiospermous exogens, which comprise four-fifths of living plants--a division to which all our native European trees, except the Coniferae, belong, and which embrace all the Compositae, Leguminosae, Umbelliferae, Cruciferae, Heaths, and so many other families--are wholly unrepresented by any fossils hitherto discovered in the Primary and Secondary formations from the Silurian to the Oolitic inclusive. It is not till we arrive at the Cretaceous period that they begin to appear, sparingly at first, and only playing a conspicuous part, together with the palms and other endogens, in the Tertiary epoch.

When commenting on the eagerness with which the doctrine of progression was embraced from the close of the last century to the time when I first attempted, in 1830, to give some account of the prevailing theories in geology, I observed that far too much reliance was commonly placed on the received dates of the first appearances of certain orders or classes of animals or plants, such dates being determined by the age of the stratum in which we then happened to have discovered the earliest memorials of such types. At that time (1830), it was taken for granted that Man had not co-existed with the mammoth and other extinct mammalia, yet now that we have traced back the signs of his existence to the Pleistocene era, and may anticipate the finding of his remains on some future day in the Pliocene period, the theory of progression is not shaken; for we cannot expect to meet with human bones in the Miocene formations, where all the species and nearly all the genera of mammalia belong to types widely differing from those now living; and had some other rational being, representing Man, then flourished, some signs of his existence could hardly have escaped unnoticed, in the shape of implements of stone or metal, more frequent and more durable than the osseous remains of any of the mammalia.

In the beginning of this century it was one of the canons of the popular geological creed that the first warm-blooded quadrupeds which had inhabited this planet were those derived from the Eocene gypsum of Montmartre in the suburbs of Paris, almost all of which Cuvier had shown to belong to extinct genera. This dogma continued in force for more than a quarter of a century, in spite of the discovery in 1818 of a marsupial quadruped in the Stonesfield strata, a member of the Lower Oolite, near Oxford. Some disputed the authority of Cuvier himself as to the mammalian character of the fossil; others, the accuracy of those who had assigned to it so ancient a place in the chronological series of rocks. In 1832 I pointed out that the occurrence of this single fossil in the Oolite was "fatal to the theory of successive development" as then propounded.* (* "Principles of Geology" 2nd edition 1 173.) Since that period great additions have been made to our knowledge of the existence of land quadrupeds in the olden times. We have ascertained that, in Eocene strata older than the gypsum of Paris, no less than four distinct sets of placental mammalia have flourished; namely, first, those of the Headon series in the Isle of Wight, from which fourteen species have been procured; secondly, those of the antecedent Bagshot and Bracklesham beds, which have yielded, together with the contemporaneous "calcaire grossier" of Paris, twenty species; thirdly, the still older beds of Kyson, near Ipswich, and those of Herne Bay, at the mouth of the Thames, in which seven species have been found; and fourthly, the Woolwich and Reading beds, which have supplied ten species.* (* Lyell's supplement to 5th edition of "Elements" 1857.)

We can scarcely doubt that we should already have traced back the evidence of this class of fossils much farther had not our inquiries been arrested, first by the vast gap between the Tertiary and Secondary formations, and then by the marine nature of the Cretaceous rocks.

The mammalia next in antiquity, of which we have any cognisance, are those of the Upper Oolite of Purbeck, discovered between the years 1854 and 1857, and comprising no less than fourteen species, referable to eight or nine genera; one of them, Plagiaulax, considered by Dr. Falconer to have been a herbivorous marsupial. The whole assemblage appear, from the joint observations of Professor Owen and Dr. Falconer, to indicate a low grade of quadruped, probably of the marsupial type. They were, for the most part, diminutive, the two largest not much exceeding our common hedgehog and polecat in size.

Next anterior in age are the mammalia of the Lower Oolite of Stonesfield, of which four species are known, also very small and probably marsupial, with one exception, the Stereognathus ooliticus, which, according to Professor Owen's conjecture, may have been a hoofed quadruped and placental, though, as we have only half of the lower jaw with teeth, and the molars are unlike any living type, such an opinion is of course hazarded with due caution.

Still older than the above are some fossil quadrupeds of small size, found in the Upper Trias of Stuttgart in Germany, and more lately by Mr. C. Moore in beds of corresponding age near Frome, which are also of a very low grade, like the living Myrmecobius of Australia. Beyond this limit our knowledge of the highest class of vertebrata does not as yet extend into the past, but the frequent shifting back of the old landmarks, nearly all of them once supposed in their turn to indicate the date of the first appearance of warm-blooded quadrupeds on this planet, should serve as a warning to us not to consider the goal at present reached by palaeontology as one beyond which they who come after us are never destined to pass.

On the other hand, it may be truly said in favour of progression that after all these discoveries the doctrine is not gainsaid, for the less advanced marsupials precede the more perfect placental mammalia in the order of their appearance on the earth.

If the three localities where the most ancient mammalia have been found--Purbeck, Stonesfield, and Stuttgart--had belonged all of them to formations of the same age, we might well have imagined so limited an area to have been peopled exclusively with pouched quadrupeds, just as Australia now is, while other parts of the globe were inhabited by placentals, for Australia now supports one hundred and sixty species of marsupials, while the rest of the continents and islands are tenanted by about seventeen hundred species of mammalia, of which only forty-six are marsupial, namely, the opossums of North and South America. But the great difference of age of the strata in each of these three localities seems to indicate the predominance throughout a vast lapse of time (from the era of the Upper Trias to that of the Purbeck beds) of a low grade of quadrupeds; and this persistency of similar generic and ordinal types in Europe while the species were changing, and while the fish, reptiles, and mollusca were undergoing vast modifications, raises a strong presumption that there was also a vast extension in space of the same marsupial forms during that portion of the Secondary epoch which has been termed "the age of reptiles."

The Antiquity of Man - 70/91

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