奥陶纪—泥盆纪镜眼虫目三叶虫头部形态演化及其对环境变化的响应  

Morphologic evolution in the cephalon of the Ordovician-Devonian Phacopida trilobites and its responds to environmental changes

作　　者：赵琪 陈延龙 代韬 薛春玲 李花蕊 ZHAO Qi;CHEN Yanlong;DAI Tao;XUE Chunling;LI Huarui(Shaanxi Key Laboratory of Early Life and Environments/State Key Laboratory of Continental Evolution and Early Life/Department of Geology,Northwest University,Xi’an 710069,China;College of Chemical and Environmental Enigineering,Hanjiang Normal University,Shiyan 442000,China)

机构地区：[1]西北大学地质学系/大陆演化与早期生命全国重点实验室/陕西省早期生命与环境重点实验室,陕西西安710069 [2]江汉师范学院化学与环境工程学院,湖北十堰442000

出　　处：《西北大学学报(自然科学版)》2025年第2期235-245,共11页Journal of Northwest University(Natural Science Edition)

基　　金：国家重点研发计划(2023YFF0803601);国家自然科学基金(42172013,41720104002,41890844,41890843,41930319,42072003和41572002);国家级高等学校学科创新引智计划(111项目)(D17013)。

摘　　要：镜眼虫目三叶虫是奥陶纪—泥盆纪的代表性三叶虫类群,其在显生宙早期的海洋生态系统中占据重要位置,历经古生代多次重大地质历史事件。目前,对于其分类单元多样性的研究较为充分,但其形态多样性演化及与地质事件的协同关系尚不明确。该研究聚焦于奥陶纪—纪泥盆纪镜眼虫目三叶虫的形态演化及其对地质事件的响应,通过几何形态测量学对351个属的头部形态进行了分析,并基于形态空间量化了奥陶纪至泥盆纪镜眼虫目的头部形态变化。研究发现,镜眼虫目三叶虫头部的形态分异度高峰出现在中奥陶世达瑞威尔期和中泥盆世艾菲尔期;主要的衰退出现了3次,分别是晚奥陶世凯迪期、志留纪末期和晚泥盆世法门期,均与各类缺氧海退等重大环境变化事件耦合,说明镜眼虫目的头部形态演化与海平面和水体氧含量变化密切相关,这些环境因素很大程度上影响了其形态分异度的变化。除此之外,中泥盆世艾菲尔期,镜眼虫目新增属种数量下降,但同时期头部形态分异度(SOV和SOR)却上升,即形态多样性峰值出现在物种多样性峰值之后,这是由于与镜眼虫目具有相同生态位的其他生物类群在此时期大发展,抑制了镜眼虫目分类单元多样性的增加,却加剧了同生态位物种间的竞争,促使镜眼虫目新生属种发生头部形态的创新。The Phacopida are a representative order of trilobites from the Ordovician to the Devonian periods,occupying an important position in the marine ecosystem during the early Phanerozoic spannedmany significant geological events in the Paleozoic.The taxonomic diversity of Phacopida has been well investigated,but the co-evolution of its morphological disparity with geological events still needs to be clarified.This study focuses on the morphological evolution of Phacopida trilobites and its response to geological events ranging from the Ordovician to Devonian.Utilizing a geometric morphometric approach,we analyzed the shape of cephalon of 351 distinct genera and quantified the morphological changes of Phacopida from the Ordovician to Devonian based on morphospaces.We found that the peak of morphological disparity in the cephalon of Phacopida occurred in the Darriwilian and the Eifelian,and there were three major recessions,respectively:the Katian,the latest Silurian,and the Famennian,all of them appeared in periods of major environmental disturbances such as anoxic events and regressions,suggesting that the morphological evolution in the cephalon of Phacopida was closely related to oxygen content in sea water and the changes of sea level,and these environmental factors greatly affected the variation of their morphological disparity.Meanwhile,the number of new genus of Phacopida decreased during the Eifelian,but morphological disparity in the cephalon(SOV and SOR)increased in the same time,which means the peak of morphological disparity appeared after the peak of taxonomic diversity.This could be because the rising Eifelian competitors which have similar ecological niche of Phacopida,restrained the taxonomic diversity of Phacopida,but these competitors has also increased competition between species in the same ecological niche and promoted the morphological innovation in the cephalon of new species of Phacopida.

关 键 词：镜眼虫目 古生代 协同演化 形态多样性 灭绝 环境扰动 

分 类 号：P52[天文地球—古生物学与地层学]