关于晚奥陶世牙形刺属Tasmanognathus Burrett和Yaoxianognathus An的几点新认识  

NEW RECOGNITIONS ON THE LATE ORDOVICIAN CONODONT GENERA TASMANOGNATHUS BURRETT AND YAOXIANOGNATHUS AN

作　　者：杨志华[1] 景秀春[1] 王训练[1] 周洪瑞[1] 任卉 YANG Zhihua;JING Xiuchun;WANG Xunlian;ZHOU Hongrui;REN Hui(School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083)

机构地区：[1]中国地质大学(北京)地球科学与资源学院

出　　处：《微体古生物学报》2019年第2期115-129,共15页Acta Micropalaeontologica Sinica

基　　金：国家自然科学基金(41502026);973项目(2011CB403001)共同资助~~

摘　　要：本文对广泛分布于晚奥陶世浅水、暖水碳酸盐岩地层中的两个牙形刺属Tasmanognathus Burrett, 1979和Yaoxianognathus An, 1985的分类学和生物地层学的研究历史和现状进行了梳理和讨论,并基于产出于华北台地北缘内蒙古大佘太白彦花山剖面的丰富标本提出关于两属的分类和演化的几点认识。根据所发现的化石特征,本文补充了Tasmanognathus shichuanheensis An, 1985和Yaoxianognathus neimengguensis(Qiu in Lin et al., 1984)的器官分子。基于Tasmanognathus borealis An, 1985 S分子的复杂细齿结构特征,认为其符合Yaoxianognathus的属征,将其归并厘定为Yaoxianognathus borealis,器官种Tasmanognathus sigangensis Pei, 1987的各分子无一符合该属器官特征重建,其全型标本更接近于Oulodus Branson et Mehl, 1933。同时,T. sishuiensis-T. shichuanheensis-Y. borealis-Y. neimengguensis-Y. yaoxianensis表现为细齿由简单到复杂的演化过程,再一次证明两属之间演化关系明确。本文对两个属的认识,将为浅水、暖水碳酸盐岩相上奥陶统的牙形刺分类学研究和生物地层划分对比提供参考。This paper reviews the research history and present situation of the taxonomy and biostratigraphy about two Late Ordovician worldwide distributed, shallowwarm water genera Tasmanognathus Burrett, 1979 and Yao-xianognathus An, 1985. Based on rich material from the Baiyanhuashan section in the Dashetai area, Inner Mongolia, North China, some new recognitions on the taxonomy and evolutionary relationship of these two genera are proposed. Several skeletal elements of Tasmanognathus shichuanheensis and Yaoxianognathus neimengguensis were added to their apparatus reconstructions. Due to the complex arrangement of denticles of its S elements, Tasmanognathus borealis is considered to have the generic character of Yaoxianognathus, therefore was reassigned to the later genus as Yaoxianognathus borealis. None of the elements of Tasmanognahtus sigangensis sensu in Pei and Cai, 1987 is coincide with the reconstructed apparatus of Tasmanognathus, and the holotype of T. sigangensis sensu in Pei and Cai, 1987 should be reassessed. The series of T. sishuiensis-T. shichuanheensis-Y. borealis-Y. neimengguensis-Y. yao-xianensis shows the evolution trend of the denticles from simple to complex, demonstrating a clear relationship between the two genera. Therefore, this paper proposed that T. shichuanheensis is a transition species between Tasmanognathus and Yaoxianognathus. The new recognitions on these two genera will be helpful for the conodont taxo-nomy and biostratigraphy of shallowwarm water carbonate successions.

关 键 词：牙形刺 Tasmaonognathus Yaoxianognathus 晚奥陶世 内蒙古 

分 类 号：Q915[天文地球—古生物学与地层学]