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PALAEOLOGUS
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PALAEOLOGUS , a See also:Byzantine See also:family name which first appears in See also:history about the See also:middle of the 11th See also:century, when See also:George Palaeologus is mentioned among the prominent supporters of Nicephorus Botaniates, and afterwards as having helped to raise Alexius I. See also:Comnenus to the See also:throne in Io81; he is also noted for his brave See also:defence of Durazzo against the See also:Normans in that See also:year. See also:Michael Palaeologus, probably his son, was sent by See also:Manuel II. Comnenus into See also:Italy as See also:ambassador to the See also:court of See also:Frederick I. in 1154; in the following year he took See also:part in the See also:campaign against See also: A daughter of Thomas, Zoe by name, married See also:Ivan III. of See also:Russia. A younger See also:branch of the Palaeologi held the principality of Monferrat from 1305 to 1533, when it became See also:extinct. See See also:ROMAN EMPIRE, LATER, and articles on the See also:separate rulers. PALAEONTOLOGY (Gr. 7raXat6s, See also:ancient, neut. pl. ilvra, beings, and Xoyia, discourse, See also:science), the science of extinct forms of See also:life. Like many other natural sciences, this study dawned among the Greeks. It was retarded and took false directions until the revival of learning in Italy. It became established as a distinct branch in the beginning of the 19th century, and some-what later received the appellation " palaeontology," which was given independently by De See also:Blainville and by See also:Fischer von Waldheim about 1834. In See also:recent years the science of See also:vegetable palaeontology has been given the distinct name of See also:Palaeobotany (q.v.), so that " palaeontology " among biologists mainly refers to See also:zoology; but historically the two cannot be disconnected. Palaeontology both borrows from and sheds See also:light upon See also:geology and other branches of the See also:physical history of the See also:earth, each of which, such as palaeogeography or palaeometeorology, is the more fascinating because of the large See also:element of the unknown, the need for constructive See also:imagination, the See also:appeal to other branches of biological and physical investigation for supplementary See also:evidence, and the See also:necessity of See also:constant comparison with the See also:present aspects of nature. The task of the palaeontologist thus begins with the See also:appearance of life on the globe, and ends in See also:close relation to the studies of the archaeologist and historian as well as of the zoologist and botanist. That See also:wealth of evidence which the zoologist enjoys, including environment in all its aspects and See also:anatomy in its perfection of See also:organs and tissues, the palaeontologist finds partially or wholly destroyed, and his highest See also:art is that of See also:complete restoration of both the past forms and past environments of life (see Plates I. and II.; See also:figs. 1, 2, 3, 4, 5). The degree of accuracy in such anatomical and physiographic restorations from relatively imperfect evidence will always represent the See also:state of the science and the degree of its approach toward being exact or complete. Progress in the science also depends upon the pursuit of palaeontology as zoology and not as geology, because it was a See also:mere See also:accident of See also:birth which connected palaeontology so closely with geology. In See also:order to illustrate the grateful services which palaeontology through restoration may render to the related earth sciences let us imagine a vast See also:continent of the past wholly unknown in its physical features, See also:elevation, See also:climate, configuration, but richly represented by fossil remains. All the fossil See also:plants and animals of every See also:kind are brought from this continent into a great museum; the See also:latitude, See also:longitude and relative elevation of each specimen are precisely recorded; a See also:corps of investigators, having the most exact and thorough training in zoology and See also:botany, and gifted with imagination, will soon begin to restore the geographic and physiographic outlines of the continent, its fresh, brackish and See also:salt-See also:water confines, its seas, See also:rivers and lakes, its forests, uplands, plains, meadows and swamps, also to a certain extent the See also:cosmic relations of this continent, the amount and duration of its See also:sunshine, as well as something of the chemical constitution of its See also:atmosphere and the See also:waters of its rivers and seas; they will trace the progressive changes which took See also:place in the outlines of the continent and its surrounding oceans, following the invasions of the See also:land by the See also:sea and the re-emergence of the land and retreatal of the seashore; they will outline the shoals and deeps of its border seas, and trace the barriers which pre-vented intermingling of the inhabitants of the various provinces of the continent and the surrounding seas. From a study of remains of the See also:mollusca, See also:brachiopoda and other marine organisms they will determine the shallow water (littoral) and deep water (abyssal) regions of the surrounding oceans, and the clear or muddy, salt, brackish or fresh See also:character of its inland and marginal seas; and even the physical conditions of the open sea at the See also:time will be ascertained. In such manner Johannes See also:Walther (See also:Die See also:Fauna der Solnhofener Flatten Kalke Bionomisch betrachtet. Festschrift zum 7oterl Geburtstage von See also:Ernst See also:Haeckel, 1904) has restored the conditions existing in the lagoons and See also:atoll reefs of the See also:Jurassic sea of Solnhofen in See also:Bavaria; he has traced the See also:process of See also:gradual See also:accumulation of the See also:coral mud now constituting the See also:fine litho-graphic stones in the inter-See also:reef region, and has recognized the periodic laying See also:bare of the mud surfaces thus formed; he has determined the winds which carried the dust particles from the not far distant land and brought the See also:insects from the adjacent Jurassic forests. Finally the presence of the flying lizards (Pterydactylus, Rhamphorhynchus) and the ancient birds (See also:Archaeopteryx) is determined from remains in a most wonderful state of preservation in these ancient deposits. Still another example of restoration, See also:relating to the See also:surface of a continent, may be cited. It has been discovered that at the beginning of the See also:Eocene the See also:lake of Rilly occupied a vast See also:area east of the present site of See also:Paris; a water-course See also:fell there in cascades, and Munier-Chalmas has reconstructed all the details of that singular locality; plants which loved moist places, such as Marchantia, Asplenium, the covered See also:banks overshadowed bylindens, laurels, magnolias and palms; there also were found the See also:vine and the See also:ivy; mosses (Fontinalisj and Chara sheltered the See also:crayfish (Astacus); insects and even See also:flowers have left their delicate impressions in the travertine which formed the See also:borders of this lake. The Oligocene lake See also:basin of Florissant, See also:Colorado, has been reconstructed similarly by See also:Samuel Hubbard Scudder and T. D. A. See also:Cockerell, including the plants of its shores, the insects which lived upon them, the fluctuations of its level, and many other characteristics of this extinct water See also:body, now in the See also:heart of the arid region of the Rocky Mountains. Such restorations are possible because of the intimate fitness of animals and plants to their environment, and because such fitness has distinguished certain forms of life from the See also:Cambrian to the present time; the See also:species have altogether changed, but the See also:laws governing the life of certain kinds of organisms have remained exactly the same for the whole See also:period of time assigned to the duration of life; in fact, we read the conditions of the past in a See also:mirror of See also:adaptation, often sadly tarnished and incomplete owing to breaks in the palaeontological See also:record, but constantly becoming more polished by discoveries which increase the understanding of life and its all-pervading relations to the non-life. Therefore adaptation is the central principle of See also:modern palaeontology in its most comprehensive sense. This conception of the science and its possibilities is the result of very gradual advances since the beginning of the 19th century in what is known as the method of palaeontology. The history of this science, like that of all physical sciences, covers two parallel lines of development which have acted and reacted upon each other—namely, progress in exploration, See also:research and See also:discovery, and progress in philosophic See also:interpretation. Progress in these two lines is by no means See also:uniform; while, for example, palaeontology enjoyed a sudden advance See also:early in the 19th century through the discoveries and researches of See also:Cuvier, guided by his See also:genius as a See also:comparative anatomist, it was checked by his failure as a natural philosopher. The great philosophical impulse was that given by See also:Darwin in 1859 through his demonstration of the theory of descent, which gave tremendous zest to the See also:search for pedigrees (phylogeny) of the existing and extinct types of See also:animal and plant life. In future the philosophic method of palaeontology must continue to advance step by step with exploration; it would be a reproach to later generations if they did not progress as far beyond the philosophic status of Cuvier, See also:Owen and even of See also:Huxley and See also:Cope, as the new materials represent an advance upon the material opportunities which came to them through exploration. To set forth how best to do our thinking, rather than to follow the triumphs achieved in any particular See also:line of exploration, and to present the point we have now reached in the method or principles of palaeontology, is the See also:chief purpose of this See also:article. The illustrations will be See also:drawn both from vertebrate and invertebrate palaeontology. In the latter branch the author is wholly indebted to See also:Professor Amadeus W. Grabau of See also:Columbia University. The subject will be treated in its biological aspects, because the relations of palaeontology to See also:historical and strati-graphic geology are more appropriately considered under the article GEOLOGY. See also, for botany, the article PALAEOBOTANY. We may first trace in outline the history of the birth of palaeontological ideas, from the time of their first adumbration. But for full details reference must be made to the See also:treatises on the history of the science cited in the bibliography at the end of the article. I.-FIRST HISTORIC PERIOD The scientific recognition of fossils as connected with the past history of the earth, from See also:Aristotle (384-322 B.C.) to the beginning of the 19th century, in connexion with the rise of comparative anatomy and geology.—The See also:dawn of the science covers the first observation of facts and the rudiments of true interpretation. Among the Greeks, Aristotle (384-322 B.C.) See also:Xenophon (430-357 B.C.) and Straho (63 B.C.-A.D. 24) knew of the existence of fossils and surmised in a crude way their relation to earth history. Similar prophetic views are found among certain Roman writers. The pioneers of the science in the 16th and r 7th centuries put forth anticipations of some of the well-known modern principles, often followed by recantations, through deference to prevailing religious or traditional beliefs. There were the retarding influences of the See also:Mosaic See also:account of sudden creation, and the belief that fossils represented See also:relics of a universal See also:deluge. There were crude See also:medieval notions that fossils were " freaks " or " See also:sports " of nature (lusus naturae), or that they represented failures of a creative force within the earth (a notion of See also:Greek and Arabic origin), or that larger and smaller fossils represented the remains of races of giants or of pygmies (the mythical See also:idea).
As early as the middle of the 15th century Leonardo da See also:Vinci (1452–1519) recognized in seashells as well as in the See also:teeth of marine fishes proofs of ancient sea-levels on what are now the summits of the See also:Apennines. Successive observers in Italy, notably See also:Fracastoro (1483–1553), Fabio See also:Colonna (1567–1640 or 165o) and Nicolaus See also:Steno (1638–c. 1687), a Danish anatomist, professor in See also:Padua, advanced the still embryonic science and set forth the principle of comparison of fossil with living forms. Near the end of the 17th century See also: The beginnings of palaeogeography followed those of palaeometeorology. The See also:Italian geologist Soldani distinguished (1758) between the fossil fauna of the deep sea and of the See also:shore-lines. In the same year Johann See also:Gesner (1709–1790) set forth the theory of a great period of time, which he estimated at 8o,000 years, for the elevation of the shell-bearing levels of the Apennines to their present height above the sea. The brilliant See also:French naturalist Georges See also: See also:Political troubles and the dominating See also:influence of Werner's speculations checked palaeontology in Germany, while under the leadership of Lamarck and Cuvier See also:France came to the fore. J. B. Lamarck (1744–1829) was the founder of invertebrate palaeontology. The See also:treatise which laid the See also:foundation for all subsequent invertebrate palaeontology was his memoir, Sur les fossiles See also:des environs de Paris . . . (1802–1806). Beginning in 1793 he boldly advocated See also:evolution, and further elaborated five great principles--namely, the method of comparison of extinct and existing forms, the broad sequence of formations and succession of epochs, the correlation of geological horizons by means of fossils, the See also:climatic or environmental changes as influencing the development of species, the See also:inheritance of the bodily modifications caused by See also:change of See also:habit and See also:habitat. As a natural philosopher he radically opposed Cuvier and was distinctly a precursor of uniformitarianism, advocating the See also:hypothesis of slow changes and See also:variations, both in living forms and in their environment. His speculations on phylogeny, or the descent of invertebrates and vertebrates, were, however, most fantastic and See also:bore no relation to palaeontological evidence.
It is most interesting to See also:note that William See also: Cuvier (1769–1832) is famous as the founder of vertebrate palaeontology, and with See also:Alexandre See also:Brongniart (177o–1847) as the author of the first exact contribution to stratigraphic geology. Early trained as a comparative anatomist, the discovery of Upper Eocene mammals in the See also:gypsum quarries of Montmartre found him fully prepared (1798), and in 1812 appeared his Recherches sur les ossemens fossiles, brilliantly written and constituting the foundation of the modern study of the extinct vertebrates. Invulnerable in exact anatomical description and comparison, he failed in all his philosophical generalizations, even in those strictly within the domain of anatomy. His famous " See also:law of correlation;" which by its apparent brilliancy added enormously to his See also:prestige, is not supported by modern philosophical anatomy, and his services to stratigraphy were diminished by his generalizations as to a succession of sudden extinctions and renovations of life. His See also:joint See also:memoirs with Brongniart, Essai sur la geographie mineralogique des environs de Paris aver une See also:carte geognostique et des coupes de terrain (18o8) and Description geologique des environs de Paris (1835) were based on the wonderful succession of Tertiary faunas in the rocks of the Paris basin. In Cuvier's defence See also: It was Alcide Dessalines d'See also:Orbigny (1802—1857) who pushed to an extreme Cuvier's ideas of the fixity of species and of successive extinctions, and finally developed the See also:wild hypothesis of twenty-seven distinct Creations. While these views were current in France, exaggerating and surpassing the thought of Cuvier, they were strongly opposed in Germany by such authors as Ernst Friedrich von See also:Schlotheim (1764—1832) and Heinrich Georg See also:Bronn (18o0—1862); and the latter demonstrated that certain species actually pass from one formation to another. In the meantime the See also:foundations of palaeobotany were being laid (1804) by Ernst Friedrich von Schlotheim (1764—1832), (1811) by Kaspar Maria See also:Sternberg (1761—1838) and (1838) by See also:Theophile Brongniart (180x—1876). Following Cuvier's Recherches sur les ossemens fossiles, the See also:rich succession of Tertiary mammalian life was gradually revealed to France through the explorations and descriptions of such authors as Croizet, Jobert, de Christol, Eymar, Pomel and Lartet, during a period of rather dry, systematic See also:work, which included, however, the broader generalizations of See also:Henri See also:Marie Ducrotay de Blainville (1778—1850), and culminated in the comprehensive treatises on Tertiary palaeontology of See also:Paul See also:Gervais (1816—1879). Extending the knowledge of the extinct mammals of Germany, the See also:principal contributors were Georg See also:August See also:Goldfuss (1782—1848), Georg Friedrich von Jaegar (1785—1866), See also:Felix F. Plieninger (1807—1873) and Johann See also:Jacob See also:Kaup (1803—1873). As Cuvier founded the palaeontology of mammals and See also:reptiles, so Louis See also:Agassiz's See also:epoch-making See also:works Recherches sur les poissons fossiles (1833—1845) laid the secure foundations of palaeichthyology, and were followed by See also:Christian Heinrich Pander's (1794—1865) classic memoirs on the fossil fishes of Russia. In See also:philosophy Agassiz was distinctly a See also:disciple of Cuvier and supporter of the doctrine of special creation, and to a more limited extent of cataclysmic extinctions. Animals of the next higher order, the amphibians of the See also:coal See also:measures and the See also:Permian, were first comprehensively treated in the masterly memoirs of Christian Erich See also:Hermann von See also:Meyer (18or—1869) beginning in 1829, especially in his Beitrtige zur Petrefactenkunde (1829—1830) and his Zur Fauna der Vorwelt (4 vols., 1845—186o). Successive discoveries gradually revealed the See also:world of extinct Reptilia; in 182 r Charles See also:Konig (1784—1851), the first keeper of the mineralogical collection in the See also:British Museum, described See also:Ichthyosaurus from the Jurassic; in the same year William See also:Daniel See also:Conybeare (1787—1857) described See also:Plesiosaurus; and a year later (1822) Mosasaurus; in 1824 William See also:Buckland described the great carnivorous dinosaur Megalosaurus; while See also:Gideon Algernon See also:Mantell (1790—1852) in 1848 announced the discovery of See also:Iguanodon. Some of the fossil Reptilia of France were made known through St Hilaire's researches on the Crocodilia (1831), and those of J. A. Deslongchamps (1794—1867) and his son on the teleosaurs, or See also:long-snouted crocodiles. Materials accumulated far more rapidly, however, than the See also:power of generalization and See also:classification. Able as von Meyer was, his classification of the Reptilia failed because based upon the single adaptive characters of See also:foot structure. The reptiles awaited a great classifier, and such a one appeared in England in the See also:person of Sir See also:Richard Owen (1804—1892), the direct successor of Cuvier and a comparative anatomist of the first rank. Non-committal as regards evolution, he vastly broadened the See also: The path-breaking works of Lamarck were soon followed by the monumental treatise of See also:Gerard Paul See also:Deshayes (1795—1875) entitled Descriptions des coquilles fossiles des environs de Paris (1824—1837), the first of a series of great contributions by this and other authors. These and other early monographs on the Tertiary shells of the Paris basin, of the environs of See also:Bordeaux, and of the sub-Apennine formations of Italy, brought out the striking distinctness of these faunas from each other and from other molluscan faunas. Recognition of this threefold character led Deshayes to establish a threefold division of the Tertiary based on the percentage of molluscs belonging to types now living found in each. To these divisions Lyell gave in 1833 the names Eocene, See also:Miocene and See also:Pliocene.
James Hutton (1726—1797) had set forth (1788) the principle that during all geological time there has been no essential change in the character of events, and that uniformity of law is perfectly consistent with mutability in the results. Lyell marshalled all the observations he could collect in support of this principle, teaching that the present is the See also: The greatest generalization of this second period, however, was that partly prepared for by d'Orbigny, as will be more fully explained later in this article, and clearly expressed by Agassiz —namely, the law of repetition of ancestral stages of life in the course of the successive stages of individual development. This law of recapitulation, subsequently termed the " biogenetic law " by Ernest Haeckel, was the greatest philosophic contribution of this period, and proved to be not only one of the bulwarks of the evolution theory but one of the most important principles in the method of palaeontology. On the whole, as in the See also:case of vertebrate palaeontology, the pre-Darwinian period of invertebrate palaeontology was one of rather dry systematic description, in which, however, the applications of the science gradually extended to many regions of the world and to all divisions of the See also:kingdom of invertebrates. Beginning with the publication of Darwin's great works, " Narrative of the See also:Surveying Voyages of H.M.S. `See also:Adventure' and ` Beagle' " (1839), and " On the Origin of Species by Means of Natural Selection" (1859).—A See also:review of the two first classic works of Charles Robert Darwin (1809-1882) and of their influence proves that he was the founder of modern palaeontology. Principles of descent and other applications of uniformitarianism which had been struggling for expression in the writings of Lamarck, St Hilaire and de Blainville here found their true interpretation, because the geological succession, the rise, the migrations, the extinctions, were all connected with the grand central idea of evolution from primordial forms. A close study of the exact modes of evolution and of the philosophy of evolution is the distinguishing feature of this period. It appears from comparison of the work in the two great divisions of vertebrate and invertebrate palaeontology made for the first time in this article that in accuracy of observation and in close philosophical See also:analysis of facts the students of invertebrate palaeontology led the way. This was due to the much greater completeness and abundance of material afforded among invertebrate fossils, and it was manifested in the demonstration of two great principles or laws: first, the law of recapitulation, which is found in its most ideal expression in the shells of invertebrates; second, in the law of direct genetic succession through very gradual modification. It is singular that the second law is still ignored by many zoologists. Both laws were of See also:paramount importance, as direct evidence of Darwin's theory of descent, which, it will ne remembered, was at the time regarded merely as an hypothesis. Nevertheless, the tracing of phylogeny, or direct lines of descent, suddenly began to attract far more See also:interest than the naming and description of species. The Law of Recapitulation. See also:Acceleration. Retardation.—This law, that in the stages of growth of individual development (ontogeny), an animal repeats the stages of its ancestral evolution (phylogeny) was, as we have stated, anticipated by d'Orbigny. He recognized the fact that the shells of molluscs, which grow by successive additions, preserve unchanged the whole series of stages of their individual development, 3o that each shell of a Cretaceous ammonite, for example, represents five stages of progressive modification as follows: the first is the periode embryonnaire, during which the shell is smooth; the second and third represent periods of elaboration and ornamentation; the See also:fourth is a period of initial degeneration; the fifth and last a period of degeneration when ornamentation becomes obsolete and the exterior smooth again, as in the See also:young. D'Orbigny, being a special creationist, failed to recognize the bearing of these individual stages on evolution. See also:Alpheus See also:Hyatt (1838-1902) was the first to discover (1866) that these changes in the See also:form of the ammonite shell agreed closely with those which had been passed through in the ancestral history of the See also:ammonites. In an epoch-making See also:essay, On the See also:Parallelism between the Different stages of Life in the individual and those in the entire group of the Molluscous Order Tetrabranchiata (1866), and in a number of subsequent memoirs, among which See also:Genesis of the Arietidae (1889)583 and Phylogeny of an Acquired Characteristic (1894) should be mentioned, he laid the foundations, by methods of the most exact analysis, for all future recapitulation work of invertebrate palaeontologists. He showed that from each individual shell of an ammonite the entire ancestral series may be reconstructed, and that, while the earlier shell-whorls retain the characters of the adults of preceding members of the series, a shell in its own adult stage adds a new character, which in turn becomes the pre-adult character of the types which will succeed it; finally, that this comparison between the revolutions of the life of an individual and the life of the entire order of ammonites is wonder= fully harmonious and precise. Moreover, the last stages of individual life are prophetic not only of future rising and progressing derivatives, but in the case of senile individuals of future declining and degradational series. Thus the recapitulation law, which had been built up independently from the observations and speculations on vertebrates by Lorenz See also:Olen (1779-1851), Johann Friedrich Meckel (1781-1833), St Hilaire, Karl Ernst von See also:Baer (1792-1876) and others, and had been applied (1842-1843) by Karl See also:Vogt (1817-1895) and Agassiz, in their respective See also:fields of observation, to comparison of individual stages with the adults of the same group in preceding geological periods, furnished the key to the determination of the ancestry of the invertebrates generally. Hyatt went further and demonstrated that ancestral characters are passed through by successive descendants at a more and more accelerated See also:rate in each See also:generation, thus giving time for the appearance of new characters in the adult. His " law of acceleration " together with the complementary " law of retardation," or the slowing up in the development of certain characters (first propounded by E. D. Cope), was also a See also:philo- ..1d 2e 2b 3b--1 -ie.`--2o I 8p I 4c--I - 1d~-2d--f—3d 4d I 5d--) - 1eI--2e-~--3e--f—4e—•—I-- 5e— 6e---I - 1f --f - 2f 3t ----~---- 4f — ~-- 6f -{— 6f —J-- 7f —I - 1 g-..2g..f_ 3g --I-- 4g —I 5g I--6g-l---- 7g. ----~ -lb-f.2h-'--31i—~-4h 7b--~ -11 -~ 21 -r-- 3i --{-- 4 i - 71----F—8i--1 (From the American Naturalist.) sophic contribution of the first importance (see fig. 6 and See also:Plate III., fig. 7). In the same year, 1866, See also:Franz Martin Hilgendorf (1839- ) studied the shells of Planorbis from the Miocene lake basin underlying the present See also:village of Steinheim in See also:Wurttemberg, and introduced the method of examination of large See also:numbers of individual specimens, a method which has become of See also:prime importance in the science. He discovered the actual transmutations in direct genetic series of species on the successive deposition levels of the old lake basin. This study of direct genetic series marked another great advance, and became possible in invertebrate palaeontology long before it was introduced among the vertebrates. Hyatt, in a re-examination of the Steinheim deposits, proved that successive modifications occur at the same level as well as in See also:vertical succession. Melchior See also:Neumayr (1845-1890) and C. M. Paul similarly demonstrated genetic series of Paludina (Vivipara) in the Pliocene lakes of Slavonia (1875). The Mutations of See also:Waagen. Orthogenesis.—In 1869 Wilhelm Heinrich Waagen (1841-1900) entered the field with the study of Ammonites subradiatus. He proposed the See also:term "mutations " for the See also:minute progressive changes of single characters in definite directions as observed in successive stratigraphic levels. Even when seen in minute features only he recognized them as constant progressive characters or " chronologic varieties " in
contrast with contemporaneous or " geographic varieties," which he considered inconstant and of slight systematic value. More recent analysis has shown, however, that certain modifications observed within the same stratigraphic level are really grades of mutations which show divergences comparable to those found in successive levels. The collective term " mutation," as now employed by palaeontologists, signifies a type modified to a slight degree in one or more of its characters along a progressive or definite line of phyletic development. The term " mutation " also applies to a single new character and for distinction' may be known as " the mutation of Waagen." This definitely directed evolution, or development in a few determinable directions, has since been termed " orthogenetic evolution," and is recognized by all workers in invertebrate palaeontology and phylogeny as fundamental because the facts of invertebrate palaeontology admit of no other interpretation.
Among the many who followed the method of attack first outlined by Hyatt, or who independently discovered his method, only a few can be mentioned here—namely, Waagen (1869), Neumayr (1871), Wurttemberger (188o), See also:Branco (188o), Mojsisovics (1882), Buckman (1887), Karpinsky (1889), See also:Jackson (1890), See also:Beecher (189o), Perrin-Smith (1897), See also: The See also:absolute agreement in the results independently obtained by these various investigators, the interpretation of individual development as the See also:guide to phyletic development, the demonstration of continuous genetic series, each mutation falling into its proper place and all showing a definite direction, constitute contributions to biological philosophy of the first importance, which have been little known or appreciated by zoologists because of their publication in monographs of very . special character.
Vertebrate Palaeontology after Darwin.—The impulse which Darwin gave to vertebrate palaeontology was immediate and unbounded, finding expression especially in the writings of Thomas See also: To the law of " recapitulation " he unfortunately applied Hyatt's term " parallelism," a term which is used now in another sense. He especially pointed out the laws of the " extinction of the specialized " and " survival of the non-specialized " forms of life, and challenged Darwin's principle of selection as an explanation of the origin of adaptations by saying that the " survival of the fittest " does not explain the " origin of the fittest." He personally sought to demonstrate such origin, first, in the existence of a specific See also:internal growth force, which he termed bathmic force, and second in the direct inheritance of acquired See also:mechanical modifications of the teeth and feet. He thus revived Lamarck's views and helped to found the so-called neo-Lamarckian school in America. To this school A. Hyatt, W. H. Dail and many other invertebrate palaeontologists subscribed. History of Discovery. Vertebrates.—In discovery the See also:theatre of interest has shifted from continent to continent, often in a sensational manner. After a long period of gradual revelation of the ancient life of See also:Europe, extending eastward to See also:Greece, eastern See also:Asia and to Australia, See also:attention became centred on North America, especially on Rocky See also:Mountain exploration. New and unheard-of orders of amphibians, reptiles and mammals came to the surface of knowledge, revolutionizing thought, demonstrating the evolution theory, and solving some of the most important problems of descent. Especially noteworthy was the discovery of birds with teeth both in Europe (Archaeopteryx) and in North America (Hesperornis), of Eocene stages in the history of the horse, and of the See also:giant drnosauria of the Jurassic and Cretaceous in North America. Then the stage of novelty suddenly shifted to South America, where after the pioneer labours of Darwin, Owen and Burmeister, the field of our knowledge was suddenly and vastly extended by explorations by the brothers Ameghino (See also:Carlos and Florentino). We were in the midst of more thorough examination of the ancient world of See also:Patagonia, of the Pampean region and of its submerged See also:sister continent Antarctica, when the See also:scene shifted to North See also:Africa through the discoveries of Hugh J. L. Beadnell and Charles W. See also:Andrews. These latter discoveries See also:supply us with the ancestry of the elephants and many other forms. They See also:round out our knowledge of Tertiary history, but leave the .problems of the Cretaceous mammals and of their relations to Tertiary mammals still unsolved. Similarly, the Mesozoic reptiles have been traced successively to various parts of the world from France, Germany, England, to North America and South America, to Australia and New Zealand and to See also:northern Russia, from Cretaceous times back into the Permian, and by latest reports into the Carboniferous. Discovery of Invertebrates.—The most striking feature of exploration for invertebrates, next to the world-wide extent to which exploration has been carried on and results applied, is the early appearance of life. Until comparatively recent times the molluscs were considered as appearing on the limits of the Cambrian and Ordovician; but Charles D. See also:Walcott has described a tiny lamellibranch (Modioloides) from the inferior Cambrian, and he reports the gastropod (?) genus Chuaria from the pre-Cambrian. Cephalopod molluscs have been traced back to the straight-shelled nautiloids of the genus Volborthella, while true ammonites have been found in the inferior Permian of the Continent and by American palaeontologists in the true coal measures. Similarly, early forms of the crustacean sub-class Merostomata have been traced to the pre-Cambrian of North America. Recent discoveries of vertebrates are of the same significance, the most primitive fishes being traced to the Ordovician or See also:base of the Silurian,2 which proves that we shall discover more Professor Bashford See also:Dean doubts the See also:fish characters of these Ordovic Rocky Mountain forms. Frech admits their fish character but considers the rocks infaulted Devonic. ancient chordates in the Cambrian or even pre-Cambrian. Thus all recent discovery tends to carry the centres of origin and of dispersal of all animal types farther and farther back in geological time. Additional information and CommentsThere are no comments yet for this article.
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