中三叠世多板类在我国的首次发现  

FIRST DISCOVERY OF MIDDLE TRIASSIC POLYPLACOPHORA (MOLLUSCA) IN CHINA

作　　者：冯儒林 

机构地区：[1]贵州省地质矿产局区域地质调查大队,贵阳550011

出　　处：《古生物学报》1992年第6期724-729,共6页Acta Palaeontologica Sinica

摘　　要：报道我国首次发现的三叠纪多板纲(Polyplacophora)鳞肋目(Lepidopleurina)鳞肋科(Lepidopleuridae)的—新属——中国石鳖(Sinochiton).新属保存较完整,贝体中等大,椭圆形,长宽比为1.44∶1;中间板宽远大于壳长,长方形,半圆形拱凸,壳顶不突出,后缘近直,中心区十分宽大,侧区很窄,或不明显,缝合片及嵌插板不发育;贝体具圆形环带.新属与菊石 Balatonites 共生,时代属 Anisian 期.新属与北美下二叠统的 Ochmazochiton Hoare, 1984 及宾夕法尼亚系的 Pedanochiton Debrock, Hoare et al 近似,它们之间可能存在着亲缘关系.The Polyplacophora (Mollusca) of Middle Triassic (Anisian) almust have been forgotten except for a doubtful genus Trachypleura Jaeckel, 1900 (T. triadomarchica Jaeckel) from the Middle Triassic of Germany in the past. This problem deserves our further study. All in all, Middle Triassic Polyplacophora (Mollusca) are extremely rare. The Middle Triassic Polyplacophora described in this paper were collected by members of our team in May, 1987 during their geological survey at Datang, 10km east of Wangmo county town from black grey argillaceous limestone of the Middle Triassic (Anisian) Xinyuan Formation, in association with the typical ammonoid Balatonites of Anisian. Through studies, the author considers that these fossil polyplacophorans belong to a new genus of Lepidopleuridae Pilsbury, 1892, under the name of Sinochiton gen. nov. This discovery of rare fossils not only fills some blanks of Triassic Polyplacophora in China but also provides material for studying the development and genetic evolution of the polyplacophoran animals. Systmatic Palaeontology Class Polyplacophora de Blainville, 1816 Order Lepidopleurina Thiele, 1910 Family Lepidopleuridae Pilsbry, 1892 Sinochiton gen. nov. Type species Sinochiton guizhouensis gen. et sp. nov. Diagnosis (1) Polyplacophoran in medium size; (2) head valve and tail valve possibly semicircular in outline; (3) intermediate valves much wider than long, oblong in outline, highly and roundedly arched, wtihout jugal angie, with central area very broad, lateral areas quite narrow, apex not projecting, and posterior margin nearty straight; (4) surface ornamented with a series of irregular discontinuous transverse lines; (5) suture laminae probably short, broad, extending onto, anterolateral corners, with insertion plates undeveloped, possibly no slits and teeth; (6) girdle rounded, narrow, ornamented with minute granules and transverse wrinkles. Discussion This new genus is similar to Ochmazochiton Hoare, 1984 in outline of intermediate valves, but differs from the latter in the d

关 键 词：中三叠世 多板纲 贵州 

分 类 号：Q915.817[天文地球—古生物学与地层学]