First report of fossil "keratose" demosponges in Phanerozoic carbonates: preservation and 3-D reconstruction.

摘要: Fossil record of Phanerozoic non-spicular sponges, beside being important with respect to the lineage evolution per se, could provide valuable references for investigation Precambrian ancestral animal fossils. However, although modern phylogenomic studies resolve demosponges as sister group remaining spiculate demosponges, fossil former is extremely sparse or unexplored compared that latter; Middle Cambrian Vauxiidae Walcott 1920, only confirmed taxon demosponges. Here, we describe carbonate materials from Devonian (Upper Givetian Lower Frasnian) bioherms northern France and Triassic (Anisian) microbialites Poland most likely represent remnants keratose These putative fossils are preserved automicritic clumps. They morphologically distinguishable microbial fabrics but similar other sponge fossils, except skeletal elements consist fibrous networks instead assembled spicules. Consistent immunological behavior these skeletons often form a rim at edge aggregate, separating inner part aggregate foreign objects. To confirm architecture networks, two specimens thorectid comparison were processed three-dimensional (3-D) reconstruction using serial grinding tomography. The resulting reconstructions three-dimensionally anastomosing, like their irregular nonhierarchical meshes indicate verongid affinity, precise taxonomic conclusion cannot be made based on alone. This study preliminary effort, an start identify in carbonates re-evaluate fossilization potential.