生物群的地理分布受各种生物和环境因素的影响，对于不同地史晚期以及不同的生物类型，控制生物群分布的主导因素也不同的。就侏罗纪古大西洋双壳类动物群而言古地理和古气候条件是影响其分布的主要环境因素。

Faunal distribution is generally thought to be a result of the interaction of various related biological and environmental factors. However, for different geological time intervals and for different organisms, decisive factors governing biogeographical patterns may be different. The bivalve data obtained from the Jurassic Proto Atlantic indicate that latitudinal temperature gradients and palaeogeographical factors have greatly contributed to the distribution of bivalve faunas. A number of Jurassic characteristic bivalves from the Proto Atlantic show a clear latitudinal control. The northward dispersal of several bivalve taxa of Tethyan affinity during the Early and Middle Jurassic might have been a result of climatic amelioration. The physical barriers hindered faunal exchange and seaways promoted faunal spread. All these factors are influenced by other environmental conditions.e; Gassmann equation; elastic modulus

Q915.817.4 Q914.5