The unexpected occurrence of enigmatic'percevalicrinids'(Echinodermata,Crinoidea)in the Lower Jurassic strata of North Africa—Implications for their stratigraphic and palaeogeographic distribution and discussion on their belonging to the subfamily Balanocrininae  

作　　者：Mariusz A.Salamon Madani Benyoucef Karolina Paszcza Faycal Mekki Imad Bouchemla Bartosz J.Plachno 

机构地区：[1]University of Silesia in Katowice,Faculty of Natural Sciences,Bedzinska 60,PL-41-200 Sosnowiec,Poland [2]Laboratoire de Géomatique,Ecologie et Environnement,Mustapha Stambouli University,29000 Mascara,Algeria [3]Jagiellonian University in Krakow,Faculty of Biology,Institute of Botany,Gronostajowa Street 9,PL-30-387 Cracow,Poland

出　　处：《Journal of Palaeogeography》2023年第3期434-447,共14页古地理学报（英文版）

基　　金：supported by the National Science Centre,Poland(www.ncn.gov.pl)-Grant No.2020/39/B/ST10/00006.

摘　　要：The marl and limestone alternations of the Lower Jurassic Ain Ouarka and Ain Rhezala formations(Pliensbachian-Toarcian)in the western Saharan Atlas,Northwest Algeria,yield a diverse micro-and mac-rofauna,including moderately numerous crinoids,which are represented by remains of isocrinids,i.e.,Bal-anocrinus ticinensis Hess and columnals of the genus Percevalicrinus.So far,the latter genus has been observed from the Upper Jurassic-Lower Cretaceous strata of Eurasia,North America,and the African continent.Thus,the present find is the oldest record of this crinoid genus,and the second one from the southern Tethyan margin.In this paper,it is shown that Percevalicrinus,which is traditionally regarded as a representative of the subfamily Balanocrininae,displays several features of the subfamily Isocrininae.The crinoid assemblage and associated facies and invertebrate fauna are typical of a low-energy deep outer shelf/ramp(below the storm wave-base)setting.

关 键 词：ECHINODERMS CRINOIDS Isocrinids Percevalicrinids Percevalicrinus Lower Jurassic Algeria Maghrebian Tethys 

分 类 号：P531[天文地球—古生物学与地层学] Q959[天文地球—地质学]