The Early Carboniferous Rugose Coral Fauna In Canglaila Area Of Qiangtang Basin, North Tibet And The Cladistic Analysis Of Axophyllum

The rugose corals studied in present paper were collected from the Dongfengling Formation in Zaduo County, Qinghai and Baqing County, Xizang (Tibet), China. Nine genera and 15 species, including 1 new species and 8 undefined species are described. They are Axophyllum equitabulatum (Fan),A. jamdaense Fan, A. sp., Actinocyathus sp., Diphyphyllum jamdaense Fan, D. fasciculatum (Fleming), D. dedaense sp.nov., Siphonodendron sp.,Palaeosmilia murchisoni Edwards et Haime, P. sp.,Kueichouphyllum sp.,Dibunophyllum cf. turbinatum M'Coy,D. sp., Arachnolasmella sp. and Carruthersella sp..The rugose coral fauna of the Dongfengling Formation in Zaduo County, Qinghai and Baqing County, Xizang are a kind of mixed fauna. Suborder Lonsdaleiina Axophyllum and Aulophyllina Dibunophyllum, large triple-zoned solitary corals, are the main elements in the rugose coral fauna found in the Dongfengling Formation in Zaduo county, Qinghai. While suborder Lithostrotionina Diphyphyllum, fasciculate compound corals, are dominating species in the Dongfengling Formation in Baqing County, Xizang.A method of cladistic analysis is tentatively used to evaluate the systematic relationship of 9 Axophyllum species on the basis of following 8 character states: corallite size, number of septa, length of cardinal septum, length of minor septa, size of axial column, complexity of axial structure, development of dissepiments, and shape of tabulae. The result of cladistic analysis suggests that A.simplex and A. equitabulatum are rudimentary in characters, A. retiforme and A. magnicolumellatum are within a sister group at the beginning of the cladogram, A.minor and A.tenellum are within another sister group at the end of the cladogram, which shows that they have even advanced characters. A.minor, A.tenellum and A.jamdaense have tied phylogenetic relationship.