Without doubt the most far-reaching causes of extinction of marine animals during past times have been those elianges in the rehuive levels of land and sea by which the water has been largely drawn off from the epicontinental shallow seas and from the continental shelf or littoral zone during intervals of isostatic readjustment. As a consequence of such readjustments, which also mark the openings of hew geological periods, the faunas inhabiting the shallow seas have been driven into deeper water and have suffered an- nihilation, with the exception of scattered parties which found shelter in some harbors of refuge and thus served to furnish the nuclei for new faunas which evolved under future more favorable con- ditions.
D1.STRIELT10.X OF Obgaxisms IX THE Past. De- tailed information regarding the range of the va- rious fossil animals throughout the geological formations is given in the articles on the separate groups and genera, and the range of fossil plants is described in the article Paleoisotany. It is necessary here to give only a general view of the distribution of those grou]js of animals which are of most importance to the student of strati- graphic paleontolog;v. The vertical divisions of the table represent geological periods, and the thickness of the black lines indicates the relative expansion of the groups. The selection of the group names is based entirely upon their impor- tance as fossils and has nothing to do with their rank as members of a zoological classification.
BiBUOGRAPHY. Pictet, Traiie de palcontologie (Paris. 1853.57): Owen, Manual of Palwontoloffy (7th ed., London, 1871); Nicholson and Lyd- deker, id. (Edinburgh and London, 1889); De Lapparent, Traite de geologic (4th ed., Paris, 1900; Fischer, Manuel de conchyliologie et de paUontologie conchyliologique (Paris, 1888); Freeh, Lethcea Geognostica, vols, i.-iii. (Stutt- gart, 1883-1901); Schimper, Traite de paUontolo- gie vigitale (Paris, 1809-74); Renault. Cours de botanique fossile (ib., 1881-8,5): Gaudry, Les en- ehainements du monde animal duns les temps geologiques (ib., 1883-90); id., E.isai de palcon- tologique philosophique (ib., 1896); Huxley, 'I'rinciples and Methods of Paheontology," Smithsonian Institution, Annual Report (Wash- ington, 1869); Koken. PaUontologie und Deseendenzlehre (Jena, 1902); id.. Die Vorioelt und ihre Entwickeluntisqesehichte (Leipzig, 1893); id., Die Leitfossitten (I..eipzig. 1890); Marr. The Principles of Stratigraphical Geology (Cambridge, 1898); JIarsh, Histoty and Methods of Palwontological Research (Xew Haven. 1879); Miller, North American Geology and Palceontol- ogy for the Use of Amateurs, Students, and Scien- tists, with tico Appendices (Cincinnati, 1889- 97); Neumayr, Erdgeschichte (Leipzig, 1892); id.. "Klimatische Zonen wiihrend der Jura- und Kreide-Zeit." Denkschriften der kaiserlichcn Akndemie der Wissenschaften (Vienna, 1883); Ortniann. "An Examination of the Arguments by Xeumayr for the Existence of Climatic Zones in .Jurassic Time." American Journal of Science. 4 series, vol. i. (Xew Haven, 1896); Osbom, "The Paleontological Evidence for the Transmission of Acquired Characters." Amer- ican Xaturalist. vol. xxiii. (Boston, 1889); "The Geological and Faunal Relations of Europe and America During the Tertiary Period," Annals of the Xeu: York Acadcmii of Sciences, vol. xiii. (New York. 1900); '"The Law of Adaptive Radia- tion," American yaturalist, vol. xxxvi. (Boston, 1902); Packard. A Half Century of Evolution with .Special Reference to the Etlect of Geologi- cal Changes on Animal Life," Proceedings of the American Association for the .idrancement of Science, vol. xlvii. (Salem, 1898); Schu- chert and Ulrich, --Paleozoic Seas and Bar- riers of Eastern Xorth America," Bulletin of the New York State Museum, Xo. 52 (Albany, 1902); Scott, "Paleontology as a Morphologic Discipline," Science, new series, vol. iv. (New York, 1896); "Comparatice Study of Paleontol- ogy and Phylogeny," Journal of Geology, vol. v. (1897); -'The Biogenetic Law from the Stand- point of Paleontology," Jounuil of Geology, vol. viii. (1900); "Principles of Palcontologie Corre- lation," Journal of Geology, vol. viii.' (1900); Suess, Das Antlitz der IJrde, vols, i.-ii. ( Leipzig, 1883-88); Suess and Margerie, La facede la terre, vols, i.-iii. (Paris, 1807-1902); Walther, Einlei- tung in die Geologic als hi.storische Wissen-^chaft (Jena, 1893-94); "Ueber die Lebensweise fossiler ileeresthiere," Zeitschrift der deutsehen geo- logischen Gesellschafl, vol. xlix. (Berlin. 1897); Weller, "A Century of Progress in Paleontology," Journal of Geology, vol. vii. (Chicago, 1899); "A Circum-Insular Paleozoic Fauna." Journal of Geology, vol. iii. (189:5); "The Silurian Fauna Interpreted on the Epicontinental Basis," Jour- nal of Geology, vol. vi. (1898); Williams, "The Scope of Paleontology and Its Value to Geolo- gists," American Geologist , vol. X. (Minneapolis, 1892); id., Geological Biology (New York, 1895); Woods, Elementary I'alcoiilolugy for Geological Students, 3d edition (Cambridge, 1902); Quen- stedt, Handbuch der Petrefaktenkunde (Tiibin- gen, 1885); Zittel, Uaiulhuch der Paluontologic (Leipzig, 1876-92); id., "Palseontology and the Biogenetic Law," Natural Science, vol. vi. (Lon- don. 1895); id., Geschichte der Geologic und Paliiontologie bis Ende des 19. Jahrhunderts (Leipzig, 1899; translated by Ogilvie Gordon, (Xew York, 1901): Hoernes, Paliiontologie (Leipzig, 1899); Zittel and Eastman, Textbook of Paleontology (Xew Y'ork, 1900-02). Annual lists of the current literature are piblished by the United States Geological Survey and by the Geological Society of London, and in Neues Jahrbuch fiir Mineralogie, Geologic und Paliion- tologie (Stuttgart). Bibliographic references to the literature on the various classes of fossil organisms are inserted under their individual titles.
See the following articles: GEOLOGY; DlSTRIBU- TioxoF .xiMALS: Ecology; Evolitiox; Xeola- MABCKiSM; Oceanography; Rock; Petrology: Biology; Botany; Zoology; Classification of Animals; Heredity; Paleobotany; etc.
PA'LEOTROP'ICAL, or ETHIOPIAN, REGION (from Gk. jra,oi6s palaios, ancient +
Eng. tropical). A grand division in zoogeog-
raphy composed of Africa south of the Sahara
and Mailagascar. The second name is the better,
because only a part of the tropical regions of the
Old World "are included. Four suhregions were
delimited by Sclater and Wallace: (1) That
part of Africa north of the Tropic of Capricorn
as far as the Tropic of Cancer (including
Southern Arabia), except the Congo basin; (2)
West Africa, or the eipuitorial Congo forest
region; (3) South Africa; (4) Madagascar and
the neighboring islands. This is one of the Ik'sI
ilelined of the zoological regions, and has been
