黑龙江下城子组类三角蚌的复合模化石及其形态和沉积学意义

COMPOSITE MOULD OF TRIGONIOIDES (NON-MARINE BIVALVIA) FROM XIACHENGZI FORMATION OF HEILONGJIANG AND ITS MORPHOLOGICAL AND SEDIMENTOLOGICAL SIGNIFICANCE

复合模化石是贝壳被溶蚀后，由于早期成岩压缩作用的影响，原贝壳的内模和外模互相叠加压印而成的化石，其正、负模上均印有原壳的内面和外表的特征。这种化石具有形态和沉积学意义。

Composite moulds,which are characterized by both positive mould (internal compositemould) and negative mould (external composite mould) bearing the features of both interior and exterior of the original shell,such as hinge teeth,muscle scars,radial ribs and concentric growth line.s,are formed by the superimposition of internal and external moulds dueto sedimentary compaction during or after the shell dissolution.