广西盔甲鱼类化石

本文记述了产自广西泥盆系的两件盔甲鱼类标本,其一为 Tridensaspis magnoculus gen.et sp. nov., 代表了盔甲鱼目中的一个新科;另一为盔甲鱼属中一个新种 Eugaleaspis lianhuashanensis sp. nov. 文中结合前人对盔甲鱼类化石的记述资料,对盔甲鱼类的系统关系作了初步的分支分析,以期加深我们对盔甲鱼类系统关系的认识,使现有的盔甲鱼类化石资料,能为生物地理学分析中的分支-替代方法所应用.

FOSSIL EUGALEASPID FROM GUANGXI

Two specimens of Eugaleaspids are described in this paper. One is Tridensaspis magnoculus (gen. et sp. nov.), which Was colleeted from Yujiang Formation in Xiangzhou, represents a new family among Eugaleaspiformes. The anether is Eugaleaspis lianhuashnensis (sp. nov.), which was collected from Lianhuashan Formatlcn in Guixian. In addition, the phylogenetic relationship of Eugaleaspid are briefly discussed using the cladistic analyze method. Eugaleaspiformes (Liu) 1980 Tridensapidae (fam. nov.) Cephalic shield nearIy triangular in shape. Having a marked rostral Precess. Cornua developed, projecting in lateral direction. With a sensory canal system which similar to that of Eugaleaspids. Tridensaspis magnoculus (gen. et sp. nov.) (Text-fig. 1; Pl. I, fig. 1) Small size. Cephahe shield nearly triangular in shape. Rostral process marked. Pectoral cornua developed, projectiag in lateral dimection. Orbital openings large, facing dorsally. Naso-hypophysial openigg very long, slit-like in form. The system of sensory canal ave Eugaleaspid pattern, there being a strongly developed U-shaped sensory canal between orbital openings. Interzonal Part of shield silort whih a slight convex posterior margin, extending beyond cornua Posteriorly. this genus differs from the ather Eugalenspids (exeluing Nanpanaspis) in a nearly triangular cephalic shield, directing to lateral cornua and very developed rostral process erc. On the other hand, it's similar in the features naso-hypophysial opening and sensory canal to the others. Early Devonian, lower part of Yujiang Farmation; Xiangahou, Guangxi. Eugaleaspidae (Liu) 1980 Eugaleaspis (Liu) 1980 E. lianhuashanensis (sp. nov.) (Text-fig. 2; Pl. I, fig. 2) The new species is the largest of known Eugaleaspis. Estmated beyond 115 mm in width of the cephalic shield. Cephalic shield broad, rostraI margin obtusely round without rostral angle. Lateral margins slight convex. Pectoral cornua develvped. Orbital openings small relatively to its cephalic shield. Naso-hypaphysial opening both wider and longer. Interzonal part appeavs short. This species is very similar in several features to E. xujiachongensis, but differs from the latter in Iarger size, wider naso-hypophysJal and smaller orbital openings. Early Devonian, Lianhuashan Formation; Guaxian, Guangxi.