桂北地区早石炭世杜内期的长身贝类的发现及其生物古地理意义

在广西北部兴安县高尚镇金子山剖面下石炭统鹿寨组底部，新发现了长身贝类腕足化石，包括1新种、1个相似种、6个未定种和2个属种未定类型。这些长身贝类以Productellidae和Productidae科的分子为主，另有少量Echinoconchidae和Monticuliferidae科的分子。这些长身贝类全部属于生活在静水环境中的薄壳类型，无一与华南同期地层中已知类型相同。它们之间的差异可能反映了不同沉积环境条件对腕足动物群属种的控制。在鹿寨组底部发现的长身贝类以及近年在桂林南边村和黔南睦化剖面腕足动物群的发现显示出华南台缘斜坡―盆地相区杜内阶中的腕足动物群具有极高的属种分异度，不但有大量见于世界其他地方同期动物群中的分子，也包含有不少原本认为只在维宪阶或更高层位出现的类型或全新的类型，说明华南台缘斜坡―盆地相区不但与世界其他地区的腕足动物群之间存在密切的生物地理区系联系，而且华南台缘斜坡―盆地相区是杜内期腕足动物起源和辐射演化的重要策源地之一。许多属种可能是在这里起源，并迁移扩散到其他地方。

Productoid brachiopods from the Tournaisian of Lower Carboniferous in northern Guangxi, South China:Discovery and their biopalaeogeographical significance

The Tournaisian productoid brachiopods, discovered from the base of the Luzhai Formation on the Jinzishan Section,Xing’an county, Guangxi of South China, including a new, a conformis and 6 indeterminate species, plus two forms described in open nomenclature, were described in this paper. These productoids are dominated by the forms of the families Productellidae and Productidae, and have only a few representatives of the echinoconchids and monticuliferids. All of the productoids belong to thin-shelled types dwelling in a low-energic environment and none has been recorded in other places of South China. The difference on the productoid brachiopod composition between the Jinzishan Section and other places in South China probably resulted from their different environmental conditions’ controlling . The productoids from Xing’an and the data recently discovered from the Nanbiancun of Guilin and Muhua of south Guizhou revealed that the Tournaisian brachiopod fauna in the slope margin to basinal facies of South China has an exceptionally high taxonomic diversity. It not only has abundant forms that characterizes the Tournaisian brachiopod faunas out of South China, but also contains many taxa that are new or previously considered to be stratigraphically restricted in horizons higher than the Tournaisian Stage. It is suggested that the slope margin to basinal facies of South China not only has a close biogeographical relationship with other places of the world, but also is one of the important origination and radiation centers of the brachiopods during the Tournaisian, from which many new genera and species are originated and then migrated to spread all over the world.