安徽巢湖下三叠统初始巢湖裂齿鱼的再研究

Redescription of Chaohuperleidus Primus(Actinopterygii,Perleidiformes)from Lower Triassic of Anhui Province,South China

初始巢湖裂齿鱼(Chaohuperleidus primus)产自安徽省巢湖市马家山采石场南陵湖组上段地层(早三叠世奥伦尼克期斯帕斯亚期),由于模式材料保存很差,其骨骼学特征未被完整地记述。依据模式材料及同一层位发现的3件保存完整的新材料,补充描述初始巢湖裂齿鱼的骨骼解剖信息,修正其属征,复原其头骨的骨骼模式。修正后的巢湖裂齿鱼属征支持以往的分类学结论,“顶骨与膜质翼耳骨愈合形成的骨块具有发育的前、中、后凹线,鳃盖骨与下鳃盖骨高度近等,下鳃盖骨具大的圆形前背突”是该属可能的近裔性状。巢湖裂齿鱼属与裂齿鱼属(Perleidus)的形态特征最相似,除可能的近裔性状外,与后者不同之处是次眶骨、鳃条骨和轴上鳍条的数量更多。依据巢湖裂齿鱼属头骨的骨骼特征,与以往错误地归入裂齿鱼目的早三叠世类群及裂齿鱼目内最相近的类群进行解剖学比较和讨论,为新鳍鱼类干群的谱系分析提供新的解剖学依据。

Chaohuperleidus primus has yet to be completely described due to the limit of the original material which were collected from Upper Member of the Nanlinghu Formation(Spathian,Olenekian,Early Triassic)at Majiashan quarry,Chaohu City,Anhui Province.The taxon was redescribed in detail by adding three complete specimens from the type horizons.The generic diagnosis of Chaohuperleidus was revised mainly based on newly recognized anatomical information,of which the following characters‘the fused parietal and dermopterotic with anterior,middle and posterior pit-lines;the operculum and suboperculum of nearly equal in height with the latter having a large rounded anterior dorsal process’were possible apomorphies of Chaohuperleidus.The previous taxonomic assignment of the Chaohuperleidus was confirmed,which was similar to the Ladinian(Middle Triassic)genus Perleidus but differed the latter in having more suborbitals,branchiostegal rays and epaxial fin rays besides its possible apomorphies.The skull pattern of the Chaohuperleridus primus was exhaustively reconstructed and was anatomically compared with the Early Triassic taxa which were wrongly classified into the Perleidiformes and some newly described stem neopterygians.The result herein will provide new anatomical evidences for the phylogeny analysis of the stem neopterygians that is open to discuss.