Data from: The earliest reef-building anthaspidellid sponge Rankenella zhangxianensis n. sp. from the Zhangxia Formation (Cambrian Series 3), Shandong Province, China

This study reports the earliest known reef-building anthaspidellid sponge, Rankenella zhangxianensis n. sp., from the Cambrian Series 3 (late Stage 5–early Guzhangian) deposit of the Zhangxia Formation, Shandong Province, China. Rankenella zhangxianensis mostly occurs within Epiphyton-Rankenella-Cambroctoconus reefs, with minor occurrence from inter-reef grainstone. The species has anthaspidellid-type regular ladderlike spicule networks consisting of dendroclones and trabs, and is characterized by trabs parallel/subparallel to the gastral surface that diverge and meet the dermal surface, which is typical of the genus. Compared to R. mors and R. hamdii, reported from the late Cambrian Series 2–late Cambrian Series 3 of Australia and the late Cambrian Series 3–early Furongian of Iran, respectively, R. zhangxianensis is characterized by a relatively thicker wall, high angle (~90°) between dermal surfaces and intersecting trabs, and minor occurrence of differentiated canals. On the other hand, R. zhangxianensis mainly shows obconical shape, which is far less diverse than the other two species showing conicocylindrical, digitate, explanate, or bowl shapes. These Cambrian Series 3 reefs from China are the ancestors of the Furongian anthaspidellid-microbial reefs and the Early Ordovician anthaspidellid-microbial reefs that flourished worldwide. They represent the resurgence of reef-building metazoans after the extinction of archaeocyaths at the end of Cambrian Series 2.

本研究报道了产自中国山东省张夏组寒武系第三统（第5阶晚期—古丈阶早期）地层中已知最古老的造礁安第斯皮海绵科（anthaspidellid）海绵新种——张夏兰肯海绵（Rankenella zhangxianensis n. sp.）。该新种主要赋存于附植藻（Epiphyton）-兰肯海绵（Rankenella）-坎伯罗锥管海绵（Cambroctoconus）构成的礁体中，少量见于礁间颗粒灰岩地层内。其具有安第斯皮海绵科典型的规则梯状骨针网络，由树枝状骨针束（dendroclones）和横棒（trabs）构成，特征为横棒与胃面平行或近于平行，向外发散并连接至皮层表面，这也是该属的典型特征。相较于分别产自澳大利亚寒武系第二统晚期—寒武系第三统晚期、伊朗寒武系第三统晚期—芙蓉统早期的莫氏兰肯海绵（R. mors）与哈姆丹兰肯海绵（R. hamdii），张夏兰肯海绵具有相对更厚的体壁，皮层表面与相交横棒间夹角约90°，且分化管腔的发育程度较低。另一方面，张夏兰肯海绵整体呈倒锥形，形态多样性远低于另外两个物种——后两者分别呈现圆锥柱状、指状、扁平扩展状或碗状形态。这些产自中国的寒武系第三统礁体，是全球范围内繁盛的芙蓉统安第斯皮海绵-微生物礁以及早奥陶世安第斯皮海绵-微生物礁的祖先类群；它们代表了寒武系第二统末古杯动物灭绝后，造礁后生动物的复苏。