Del Mouro Lucas, Lerosey-Aubril Rudy, Botting Joseph, Coleman Robert, Gaines Robert R, Skabelund Jacob, Weaver James C, Ortega-Hernández Javier
Department of Organismic and Evolutionary Biology and Museum of Comparative Zoology, Harvard University, Cambridge, MA 02138, USA.
Institute of Geosciences, University of São Paulo, São Paulo 05508-080, Brazil.
R Soc Open Sci. 2024 Sep 18;11(9):231845. doi: 10.1098/rsos.231845. eCollection 2024 Sep.
Modern poriferans are classified into four classes-Calcarea, Demospongiae, Hexactinellida and Homoscleromorpha-the recognition of which in fossil specimens almost exclusively relies on spicule morphology and arrangement. Early fossil representatives of the phylum Porifera are morphologically diverse, and many of them problematically display characteristics that are incompatible with the classification scheme developed for modern taxa. Critically, hexactine spicules-a diagnostic feature of hexactinellids among modern taxa-are found in various Cambrian and Ordovician taxa that cannot be accommodated within the hexactinellid body plan. Here we describe a new poriferan from the Drumian Marjum Formation of Utah, gen. et sp. nov., which exhibits a unique combination of complex anatomical features for a Cambrian form, including a syconoid-like organization, a thick body wall, and a multi-layered hexactin-based skeleton. The hexactinellid-like body wall architecture of this new species supports a Cambrian origin of the hexactinellid body plan and provides valuable insights into character evolution in early glass sponges.
现代多孔动物被分为四个纲——钙质海绵纲、寻常海绵纲、六放海绵纲和同骨海绵纲——在化石标本中对它们的识别几乎完全依赖于骨针的形态和排列。多孔动物门的早期化石代表在形态上多种多样，其中许多呈现出与为现代分类单元制定的分类方案不相符的特征，这给分类带来了难题。至关重要的是，六放骨针——现代分类单元中六放海绵纲的一个诊断特征——在各种寒武纪和奥陶纪分类单元中都有发现，而这些分类单元无法归入六放海绵纲的身体结构模式。在这里，我们描述了一种来自犹他州德鲁米安阶马尔朱姆组的新多孔动物，新属新种，它展现出了寒武纪形态所具有的复杂解剖特征的独特组合，包括类似单沟型的组织结构、厚厚的体壁以及基于六放骨针的多层骨架。这个新物种类似六放海绵纲的体壁结构支持了六放海绵纲身体结构模式起源于寒武纪的观点，并为早期玻璃海绵的特征演化提供了有价值的见解。
