宜昌地区早志留世(Llandoverian)腕足类一新科Spinochonetidae(fam.nov.)及其意义

A New Brachiopod Family Spinochonetidae from the Llandovery(Silurian)in Yichang,Western Hubei,Central China and Its Significance

腕足类新科Spinochonetidae(fam.nov.)建立在宜昌地区志留系兰多维列统罗惹坪组下段中部(上埃隆阶)的Spinochonetes Rong,Xu et Yang(1974)和Spinolella(gen.nov.)两个属,以及一个属、种未定的分类单元的基础上。新科成员仅有从腹壳喙部伸出一根直的腹喙刺,这与Chonetoidea超科内的Strophochonetidae科以及Chonestrophiidae科众成员的铰合缘刺都是从腹壳铰合缘上伸出来的有着本质差别。另外,本文还对Spinochonetes以及它的属型种S.notata Rong,Xu et Yang(1974)进行重要图解和补充描述。与此同时,对Spinolella(gen.nov),以及S.minuta(gen.et sp.nov.)进行系统描述和对比。据目前所知,新科成员只分布于我国鄂西、黔东北、陕南和川北等地,属于上扬子台地的土族居民。因为Spinochonetidae(fam.nov.)属于腕足类独特的一个类型,演化快,贝体极小,保存精美,因此具有分类学、地层对比,以及恢复古环境等方面的重要意义。

A new brachiopod family Spinochonetidae is established based on Spinochonetes Rong, Xu et Yang, Spinolella （gen. nov. ） and a taxon of gen. et sp. indet, from the middle part （Upper Aeronian） of the Lower Member of the Luoreping Formantion in Yichang aera, western Hubei, central China. The character that only one spine originating from ventral beak of all the members of Spinochonetidae （ram. nov. ）, is different remarkably from the family Strophochonetidae and family Chonestrophiidae of which the spines originating from the ventral hinge margin. In addition, the genus Spinochonetes and its type species S. notata are illustrated, some supplementary information is added. The Spinolella （gen. nov. ） and S. minuta （gen. et sp. nov. ） are systematically described in detail and compared with each other. The populations of the new family Spinochonetidae are local inhabitants, whose distribution is restricted in western Hubei, northeastern Guizhou, southern Shanxi and northern Sichuan of the upper Yangtze Platform region, southern China based on the present data. The Spinoehonetidae （ram. nov. ）, as a specilized type of the brachiopods, with rapid evolution, well- preserved very small shell, possess the great importance for the systematic study, paleoenvironment restoring and stratigraphic correlation of the Llandoverian（Silurian）.