| 摘 要： | Changxingian ammonoids are well developed in South China, including 154 species, 33 genera and 11 families. They are mainly distributed in the southern and northern subprovinces of the South China province but are rare in the middle. According to the development of the ammonoid zone and lithologic characteristics, the two subprovinces are subdivided into six endemic areas. The above-mentioneddistribution is controlled by such factors as palaeogeographic environment and sedimentary facies.The evolution of Changxingian ammonoids of South China is characterized by distinct evolutionary stages, and the whole evolutionary history of ammonites consists of alternate episodes of"explosive" radiation, slow and steady evolution and mass extinction. The alternation of mass extinction and"explosive" radiation usually occur at the boundaries of stages(or substages)."Explosive" radiation refers to rapid proliferation of new species(or genera) within a very short geologically negligeable period of time. The origin of species can be well explained by the concept of punctuated equilibria--a new concept of evolution. Mass extinction refers to rapid, large-scale demise of taxa within a very short period of time. The cause of such an extinction might be due to the inevitable replacement of the old forms by rapidly developing new ones and the environmental changes, in addition to the global sea-level changes, extraterrestrial impacts and geomagnetic reversal.
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