Based on a multitude of both domestic and foreign literatures as well as many thin sections of the calcareous skeletal textures of fossil and recent organisms, a new classification of the calcareous skeletal textures of fossil organisms is proposed in this paper. According to their geometrical shapes and optical properties biocrystals can be divided into points, lines and plans whereas the calcareous skeletal textures are divisible into three groups: granular, fibrous and foliated. The granular texture may be further subdivided into five types: agglutinated, crypto-granular, micro-granular, crysto-granular and single crystal; the fibrous texture subdivided into five types: lamellb-cnormalo-fibrous, prismato (curved)-lamello-fibrous, prismato-fibrous, sphero-fibrous and hyalo-fibrous; the foliated texture subdivided into five types: parallelo, clino, crossed-lamellar, complex crossed-lamellar and nacreous. Although the prismatic texture may have derived by retrogressive evolution from foliated texture, for the time being it is referred here to the fibrous texture. Besides, tables showing the distribution of mineral components and calcareous textures for various animal phyla are given.While coordinating and synthesizing the data available we have found that both the mineral components and textures of calcareous fossil skeletons show an evolutional sequence. The sequence for mineral components is: silica and dolomite → phosphate →organic matter→calcite-magnesian calcite and aragonite, a sequence consistent in general with that observed in marine chemical sediments. The evolutional sequence of texture of calcareous skeletons is: granular → fibrous foliated. The granular texture occurs chiefly in algae, protozoans, sponges, archaeocyathids and echinodermates; the fibrous texture in coelen’terates and arthropods; the foliated texture in bryozoans, brachiopods, mollusks and some annelids. Such textures as single crystal, hyalo-f ibrous and nacreous represent respectively the most advanced types within echinodermates, arthropods and cephalopods. This evolution of calcareous skeletal texture of fossil organisms not only existed in phylogenesis but also within every phylum; besides, ontogeny recapitulates such an evolution as reflected in the sequence of shell layers.Except a small number of cases involving physiological process and agglutination, calcareous skeletons formed through secretion, which may be subdivided into four types: accretion, addition, molting and modification. In general, algae and protozoans secrete by protoplasm calcareous matter a a granular texture. Coelenterates secrete skeleton of the fibrous texture by ectoderm. Bryogoans, brachiopods and mollusks secrete skeleton by pallial ectoderm mostly showing various types of foliated texture. Arthropods secrete skeleton of hyalo-fibrou texture by basal pallium, which was de- rived from ectoderm. Echinodermates secrete skeleton of single crystal texture by mesoderm differentiated from endoderm. Sponges and archaeocyathids being pleurozoa have a reverse diploderm. Although secreting skeleton by ectoderm they possess a granular texture. The teitural types of spicules are similar to those of skeleton.It may be concluded from the above discussion that textures of calcareous skeletons of fossil organisms were formed under the control of evolution in the texture and the secretory fissue of embryonic layers.Secretory tissue employs the superficial organic matrix to control the precipitation of calcium carbonate. The texture of biocrystal involving granularity, shape and fabric arrangement is controlled by the molecular pattern of organic matrix which varies with secretory tissue of different organisms, hence producing different calcare-ous textures. During ontogeny the secreted calcareous texture changes with the variation of organic matrix, thus a sequence of shell layers was formed.
. 1977, 生物化石钙质结构的分类与演化(连载). 地质科学, 12(3): 219-235.
. CLASSIFICATION AND EVOLUTION OF CALCAREOUS SKELETAL TEXTURES OF FOSSIL ORGANISMS[J]. Chinese Journal of Geology, 1977, 12(3): 219-235.