华北陆块西南缘寒武系辛集组Stenotheca型和Pelagiella型壳体化石几何形态测量学初探  

PRELIMINARY GEOMETRIC MORPHOLOGICAL ANALYSIS OF THE CAMBRIAN STENOTHECA AND PELAGIELLA FOSSILS IN THE SOUTHWESTERN MARGIN OF THE NORTH CHINA CRATON

作　　者：巩梦 骆劲舟 代乔坤 刘紫薇 张崧 白琳 华洪[1] GONG Meng;LUO Jinzhou;DAI Qiaokun;LIU Ziwei;ZHANG Song;BAI Lin;HUA Hong(Shaanxi Key Laboratory of Early Life and Environments,State Key Laboratory of Continental Dynamics,Department of Geology,Northwest University,Xi'an 710069,China;Northwest University Museum,Xi'an 710069,China)

机构地区：[1]早期生命与环境陕西省重点实验室,大陆动力学国家重点实验室/西北大学地质学系,西安710069 [2]西北大学博物馆,西安710069

出　　处：《微体古生物学报》2024年第1期1-13,共13页Acta Micropalaeontologica Sinica

基　　金：国家自然科学基金项目(42172014,41621003,41890844,42130207)。

摘　　要：华北陆块普遍缺失寒武系纽芬兰统至第二统下部的地层,其西南缘较为广泛分布的辛集组是研究区内最早接受沉积的一套寒武纪地层,产出大量的小壳化石,时代为寒武纪第三期中晚期至第四期早期。辛集组的小壳化石中包括大量特征明显,具有锥状、内卷式、松旋壳体的软体动物化石。本文在华北西南缘陕西洛南县灵口地区新发现的梧桐沟剖面、焦村剖面和前人研究过的陇县柴家洼剖面寒武系辛集组中下部获取了数千枚化石标本,并从中选取了保存较为完好的32枚软体动物化石和6枚前人文献中报道的相关化石(Anabarellaaustralis Runnegar in Bengtson et al., 1990, Stenotheca transbaikalica Parkhaev, 2004, Anabarella drepanoida He et Pei, 1984,Pelagiella adunca Missarzhevsky in Rozanov & Missarzhevsky,1966,Auriculaspira adunca He et Pei,1984,Auriculaspira madianensis Zhou et Xiao, 1984)进行几何形态测量学(Geometric morphometrics)分析,该方法利用界标点或轮廓线标记样本形态结构的方式对其进行定量化研究。通过应用PAST和TPS软件,经过界标点与半界标点结合的数据采集、普鲁克迭加数据变换,进行极值观察和主成分分析,结果表明这些内卷式、松旋型软体动物标本大致可以归为两个属,即Stenotheca Salter in Hicks, 1872和Pelagiella Matthew, 1895;在研究的所有标本中,仅一枚标本未鉴定出明确结果,两枚标本鉴定结果与Stenotheca较为接近;有三枚标本与Pelagiella adunca在形态上更靠近;剩余研究标本与P.madianensis接近。与传统的形态学方法相比,该方法具有更高的准确性。该方法的应用在一定程度上改善了小壳化石的属种划分,为后续对该生物群的深入研究奠定了基础。The North China Craton generally lacks the strata from the Cambrian Terreneuvian to the lower Series 2.The Xinji Formation, as the earliest Cambrian strata in this area, probably belongs to the middle or late stage 3 to early stage 4. It has a widely distribution along the southern margin of the North China Craton, and yields a large number of small shelly fossils. Thousands of molluscan fossils were recovered from the middle and lower part of the Xinji Formation of the newly investigated Wutonggou and Jiaocun sections(locating at the Lingkou area, Luonan County of eastern Shaanxi Province) and the previously studied Chaijiawa section(in the Longxian County of western Shaanxi Province). Herein, thirty-two molluscs specimens with the distinct cyrtoconic univalve, hook-shaped apex and involute shell from the Xinji Formation of the above three sections and six related species of Anabarella australis Runnegar in Bengtson et al., 1990, Stenotheca transbaikalica Parkhaev, 2004, Anabarella drepanoida He et Pei, 1984, Pelagiella adunca Missarzhevsky in Rozanov et Missarzhevsky, 1966, Auriculaspira adunca He et Pei, 1984 and Auriculaspira madianensis Zhou et Xiao, 1984 in the previous literature were selected for comparative geometric morphological analysis. This method attempts to use landmarks or contour markers to mark the morphological characters of the specimens for quantitative research. PAST and TPS software are employed to perform the observations of extreme value and the principal component analysis after the data acquisition combined with landmarks and semi-landmarks, and Procrustes data transformation. The results show that these specimens can be roughly classified into two genera,Stenotheca Salter in Hicks, 1872 and Pelagiella Matthew, 1895. Among the specimens studied, only one specimen does not get a clear result, two specimens can be ascribed to the two species of Genus Stenotheca, and three specimens were morphologically much closer to Pelagiella adunca. The remaining specimens are probably P. madianensis.

关 键 词：内卷式松旋型软体动物化石 几何形态测量学 辛集组 寒武纪早期 

分 类 号：Q915.2[天文地球—古生物学与地层学]