CAJ | 학술논문

基于对53个形态学特征的讨论,首次开展了无颌类盔甲鱼亚纲的简约性分析,获得了3个最简约的分支图,其步长为126,一致性指数为0.508,保留指数为0.801.在此基础上,修订了盔甲鱼亚纲的分类.研究结果表明,志留纪兰多维列世至温洛克世的汉阳鱼类、修水鱼类和大庸鱼类属于盔甲鱼亚纲的基干类群.在其余盔甲鱼类中,识别出3个大的单系类群,分别是真盔甲鱼目、多鳃鱼目和华南鱼目.在盔甲鱼亚纲中,头甲背窗的起源至少发生了两次,一次在多鳃鱼目支系中,另一次在华南鱼目支系中.基于背窗特征而建立的大窗鱼类并不是一个单系类群.盔甲鱼类的年代分布指示该类群的两次辐射演化,分别是兰多维列世特列奇期基干盔甲鱼类和真盔甲鱼目的辐射演化,和早泥盆世洛霍考夫期多鳃鱼目和华南鱼目的辐射演化.
기우대53개형태학특정적토론,수차개전료무합류회갑어아강적간약성분석,획득료3개최간약적분지도,기보장위126,일치성지수위0.508,보류지수위0.801.재차기출상,수정료회갑어아강적분류.연구결과표명,지류기란다유렬세지온락극세적한양어류、수수어류화대용어류속우회갑어아강적기간류군.재기여회갑어류중,식별출3개대적단계류군,분별시진회갑어목、다새어목화화남어목.재회갑어아강중,두갑배창적기원지소발생료량차,일차재다새어목지계중,령일차재화남어목지계중.기우배창특정이건립적대창어류병불시일개단계류군.회갑어류적년대분포지시해류군적량차복사연화,분별시란다유렬세특렬기기기간회갑어류화진회갑어목적복사연화,화조니분세락곽고부기다새어목화화남어목적복사연화.
We present the first parsimony analysis of the agnathan subclass Galeaspida based on the analysis of 53 morphological characters. Three most parsimonious cladograms ( 126 steps in length; CI = 0. 508; RI = 0. 801 ) were discovered. An amended classification of the Galeaspida is proposed corresponding to the present analysis. Our results suggest that hanyangaspids, xiushuiaspids and dayongaspids from the Llandovery-Wenlock of Silurian are basal galeaspids. Within the remaining galeaspids,three major monophyletic groups ( the Eugaleaspidiformes, the Polybranchiaspidiformes and the Huananaspidiformes) are well supported. It is shown that the dorsal fenestrae of headshield evolved twice within the Galeaspida, one in the polybranchiaspidiform lineage, and the other in the huananaspidiform lineage ( nested within the Huananaspidae). The chronological distribution of galeaspids highlights two radiations of the group, one for basal galeaspids and eugaleaspids in the Telychian (Llandovery) of Silurian, and the other for polybranchiaspidiforms and huananaspidiforms in the Lochkovian of Early Devonian.