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Early Eocene orthophragminids (Foraminifera) from the type-locality ofDiscocyclina ranikotensisDavies, 1927, Thal, NW Himalayas, Pakistan: insights into the orthophragminid palaeobiogeography
Geodinamica Acta Pub Date : 2015-05-18 , DOI: 10.1080/09853111.2015.1026795
Ercan Özcan , Muhammad Hanif , Nowrad Ali , A. Osman Yücel

The study of isolated orthophragminid tests at the type-locality of Discocyclina ranikotensis Davies from the Patala Formation in Thal area (Upper Indus Basin, NW Pakistan) revealed new associations of genera Discocyclina Gümbel, and Orbitoclypeus Silvestri, not yet reported from eastern Tethys. We demonstrate that D. ranikotensis Davies, the species identity of which has been a subject of controversy in earlier works, is a valid species endemic at least to the Indo-Pakistan region. D. ranikotensis is associated with Discocyclina archiaci (Schlumberger), and very sparse Orbitoclypeus schopeni (Checchia-Rispoli), both species being key taxa for orthophragminid zonation in peri-Mediterranean Tethys. We have also identified a few discocyclinid specimens suggesting possible connection to western Tethys species D. fortisi, and a few specimens showing affinity to D. dispansa. The assemblages of orthophragminids suggest orthophragminid zone (OZ) 3 according to western Tethyan zonation scheme. The occurrence of D. archiaci extends the geographical distribution of this taxon to eastern Tethys, which hitherto was only known from peri-Mediterranean region. The typical western Tethyan asterocyclinids, nemkovellids and ribbed orbitoclypeids, first appearing at or around Paleocene/Eocene boundary (OZ 1B/2, SBZ4/5), have not been identified.

中文翻译:

来自 Discocyclina ranikotensisDavies 的类型位置的早始新世 orthophragminis (Foraminifera),1927,Thal,NW Himalayas,巴基斯坦:对 orthophragminid 古生物地理学的见解

对来自 Thal 地区(巴基斯坦西北印度河流域上游印度河流域)的 Patala 组的 Discocyclina ranikotensis Davies 的类型位置进行分离的 orthophragminid 测试的研究揭示了 Discocyclina Gümbel 属和 Orbitoclypeus Silvestri 属的新关联,但尚未从东特提斯群岛报道。我们证明了 D. ranikotensis Davies,其物种身份在早期作品中一直存在争议,是一种有效的物种,至少在印巴地区是特有的。D. ranikotensis 与 Discocyclina archiaci (Schlumberger) 和非常稀疏的 Orbitoclypeus schopeni (Checchia-Rispoli) 相关联,这两种物种都是地中海沿岸特提斯中正蝶类分带的关键类群。我们还确定了一些盘环类标本,表明可能与西部特提斯物种 D. fortisi 有联系,和一些标本显示出与 D. dispansa 的亲和力。根据西特提斯分带方案,orthophragminids 的组合表明orthophragminid zone (OZ) 3。D. archiaci 的出现将该分类群的地理分布扩展到东特提斯群岛,迄今为止仅在地中海沿岸地区已知。首次出现在古新世/始新世边界(OZ 1B/2、SBZ4/5)或周围的典型西特提斯星环类、nemkovellids 和有棱纹的轨道环化类,尚未确定。
更新日期:2015-05-18
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