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PAJLEOGRAPHY. vriptorum (Heidelberg, 187G-79) ; Chatclain, I'aU-uijruphie den classitjues latins (Paris, 1884- 00) ; id., Uiicialis Scriptiora Codicuiii Latinorum Xoiis Exeinplis lUuslrata (ib., 1901).

For abbreviations: Walther, Lexicon Diplo- iiinticum (UIra, 1750), is still the standard work. Cliassant. Dictionuaire dcs uhhrcriulioiiti (2d ed., I'aiis. 1884), is a convenient handbook. Cou- -nlt also: Allen, yotes on Abbreviations in Greek MuHiiseripts (London. 1889); Cappelli, Z)i>io>ta- lio di alihreviatiire latine ed italiane (Rome, 1S09) ; and for Knglisli documents, Martin, The lUcord Interpreter (London, 1892).

PALEONTOLOGY (from Gk. 7raAa<'or,pal!aios, ancient + 6ina, onla, pi. of &v, on, being + -X"7(a -logia, from Xiyeii/, leyein, to speak). The science which deals with the ancient life tliat has inhabited the earth during the past jHTiods of geological time. It is based upon the study of fossils, and has close alUliations « ith geologj", physiograpln", and biology. It em- braces, under a broad conception of its scope, not alone the description and classification of fossils, but also all questions relating to the nature, morphology, and physiology, bionomy and ecologj', geologic and geographic distribution, and to the ontogen)-, evolution, and phylogeny of all forms of plant and animal life that have lived upon the earth and that are now found, in more or less well-preserved condition of fos- ~i!ization, imbedded in the rocks that form the earth's crust. Paleontology is the histor3' of the organic life of the earth from its inception in remote geologic time to its culmination in the vegetable and animal life of the present era. This science was foiuidcd on an independent basis by Lamarck, Cuvier, Schlotheini, Sowcrby, Parkinson, D'Orbigny, and Goldfuss about the be- ginning of the nineteenth century, and most of the earh' paleontological literature dealt with mere descriptions and classifications of fossils. After the publication of Darwin's Oriyin of Spe- ' us in 1859, and the subsequent elaboration of the doctrine of evolution, it became evident that proof of this doctrine must be furnished largely by the paleontologists, and the study of fossil or- ganisms received a new impetus along those lines of research which bear upon the broader philo- sophical questions of the origin, evolution, and phylogeny of the various species and races of fossil animals and plants. (Juite coordinate with this development of the biological phase of paleontology has been the elaboration of that phase of the science which is more closely allied to geology: namely the more refined methods in the use of fossils as markers of geologic horizons, the investigation of the succession, migration, and evolution of fossil faunas and floras, and the determination of the physiographic changes and other causes of such phenomena.

Two lines of paleontological research may then be recognized. Certain investigators confine their attention almost entirely to the elucidation of the morphology, embryology, ontogeny or devel- opment, and phylogeny or genealogy, and to the description and classification of organic remains, noting the names only of the geological forma- tions whence the species have been derived. Such studies fall within the scope of paleobotany and paleczoiilogA-. which are essentially branches of biology. The other phases of the science of pale- ontology, and perhaps the more comprehensive of the two, may be designated as paleontologic ge- ology, stratigraphic palcontologv-, geological bi- ology, and deals with the relations existing be- tween the fossils and the rocks in which they are found. It is practically that part of his- torical geology which is based upon the study of fossils. Under this head are embraced the "fol- lowing lines of investigation, and also others not mentioned that are of more special interest: ( 1 ) The use of index fossils as markers of geological formations and horizons: (2) the assemblage, within individual formations, of species and genera of fossil plants and animals to constitute paleofloras and paleofaunas; and the study of the succession, migration, and evolution of these ancient floras and faunas, and their relations to the grander divisions of geologic time; (3) the development of facies, and the influence of the facies on the conditions of existence of the life of ancient times; (4) the study of paleogeog- raphy, comprising the determination of the phy- siographic and climatic conditions existent dur- ing the successive periods of the earth's history. All these latter lines of investigation, however closely related in their final results to the phys- ical side of geology, nevertheless dei)enil for their successful pursuit upon intimate knowledge of the purely biological aspects of paleontology, for they are based primarily upon keen discrimi- nation between allied species and upon recogni- tion of the phylogenetic relationships of the spe- cies involved.

Fossils. The nature of fossils and the modes of fossilization are described in the article Fos- sil. Xot all animals and plants of past time have been preserved to us as fossils. A large number of them were of such organization that they were hardlv likely to leave traces of their existence in the rocks. It is also known that many formations which originally contained fos- sils have suU'ered so great nietamorphism that their organic contents have l)een wholly or par- tially destroyed. Other formations have been upheaved above the level of the ocean to form part of the land and have been subjected to ero- sion, with the result that their materials have been carried down to lower levels or into the sea, there to build up deposits of later age. Yet, in spite of the many gaps which will prob- ably never be filled, the history' of organisms is being rapidly compiled with an increasing degree of continuity in the series of life epochs, the lines of descent of many races of animals and plants have been established, and the sequence of those events in geological history that bear upon the conditions of existence of e.xtinct faunas has been worked out for several portions of the earth's surface, and with a surprising degree of detail.

Through observation of the true order of super- position, the rocks of the earth's crvist have been arranged by geologists into a series of systems, stages, and formations, the lowermost being the oldest and the uppermost the youngest, and the relative succession of the individual menilwrs of this series has been determined to be the same in all parts of the world. The fossils of the difl"crcnt members of the series have been studied and de- scrilM'd. and it has been ascertained that the as- semblage of fossils found in one formation always differs more or less from the assemblage of fossil* found in the overlying ami underlying beds, and furthermore that the difference is accentuated as the distance between the formations is increased. For table of geological formations, see Geoloct.