泥盆纪锥石类Changshaconus Zhu,1985和Reticulaconularia Babcock et Feldmann,1986两属的解剖学和系统学

ANATOMY AND SYSTEMATICS OF THE DEVONIAN CONULARIIDS CHANGSHACONUS ZHU,1985 AND RETICULACONULARIA BABCOCK ET FELDMANN,1986

重新描述了湖南中泥盆世的锥石ChangshaconuscarinataZhu ,1985。通过比较 ,笔者认为Chang shaconus与产自南非泥盆系和南、北美洲下泥盆统中的ReticulaconulariaBabcocketFeldmann ,1986非常相似。Changshaconus和Reticulaconularia两属由于锥管表面横肋间具有纵向脊状构造 ,与横肋构造一起构成了网状的表面装饰 ,从而区别于其它所有锥石类化石。两属的其它特征还包括 :(1)在角沟处 ,横肋成交错状排列 ;(2 )横肋在角沟的肩部向口端明显弯曲 ;(3)面中线呈明显的脊状隆起。以上 3个特征在ClimacoconusSinclair,195 2属中存在 ,因此Changshaconus、Reticulaconularia和Climacoconus构成了一个单系类群 ,而不同于其它锥石类。这 3属又与NotoconulariaThomas,196 9和ParaconulariaSinclair,195 2两属相似 ,横肋都在角沟处呈交错状排列。

Changshaconus carinata Zhu, 1985, a Middle Devonian conulariid from Hunan Province, southeastern China, is redescribed and refigured. Changshaconus probably was most closely related to Reticulaconularia Babcock et Feldmann, 1986, which occurs in the Devonian of South Africa and the Lower Devonian of Bolivia, New Jersey, and Quebec. Changshaconus and Reticulaconularia differ from all other conulariids in having transverse ribs and interspace ridges that are arranged in such a way as to form a reticulate facial ornament. Additional characteristics of Changshaconus and Reticulaconularia include (1) interruption plus alternate arrangement and interlocking of the transverse ribs in the corner sulcus; (2) sharp bending of the transverse ribs toward the aperture on the shoulders (edges) of the corner sulcus; (3) midline of the four faces marked by an external ridge. Together, these three additional similarities are uniquely shared with Climacoconus Sinclair, 1952, and can be interpreted as evidence that Changshaconus, Reticulaconularia, and Climacoconus were members of a single, monophyletic taxon that excluded all other conulariids. This group, in turn, may have been most closely related to Notoconularia Thomas, 1969 and Paraconularia Sinclair, 1952, both of which exhibit interruption plus alternation and interlocking of the transverse ribs in the corner sulcus.