title: Siliceous spicules in a vauxiid sponge (Demospongia) from the Kaili Biota(Cambrian Stage 5), Guizhou, South China.
abstract: Fossils of the sponge Angulosuspongia sinensis from calcareous mudstones of the middle and upper part of the Kaili Formation (Cambrian Stage 5) in the Jianhe area of Guizhou province, South China, exhibit an apparently reticulate pattern, characteristic of the Vauxiidae. Energy Dispersive X-Ray Spectrometry (EDS) and Raman spectroscopy analysis indicate the presence of silica in the skeletal elements of these fossils, suggesting that this taxon possessed a skeleton comprised of spicules. This is the first confirmation of siliceous skeletal elements in fossils of the family Vauxiidae, and it lends support to the hypothesis that some early demosponges possessed biomineralized siliceous skeletons, which were subsequently lost and replaced by spongin later in the evolutionary history of this lineage. The new materials provide critical insight into the phylogeny and evolution of biomineralization in the Demosopongiae.
authors.affiliation: College of Resource and Environment Engineering, Guizhou University, Guiyang 550025, China.|State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, CAS, Nanjing 210008, China.
authors.forename: X-L
authors.initials: XL
authors.lastname: Yang
authors.affiliation: College of Resource and Environment Engineering, Guizhou University, Guiyang 550025, China.
authors.forename: Y-L
authors.initials: YL
authors.lastname: Zhao
authors.affiliation: School of Earth Sciences, The Ohio State University, Columbus 43210, USA.
authors.forename: L E
authors.initials: LE
authors.lastname: Babcock
authors.affiliation: College of Resource and Environment Engineering, Guizhou University, Guiyang 550025, China.
authors.forename: J
authors.initials: J
authors.lastname: Peng
mesh_terms: D000818:Animals; D005075:Biological Evolution; D002681:China; D005580:Fossils / Q000033:anatomy & histology*; D008855:Microscopy, Electron, Scanning; D011161:Porifera / Q000033:anatomy & histology / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry*; D013052:Spectrometry, X-Ray Emission; D013059:Spectrum Analysis, Raman
chemical_list: D012822:Silicon Dioxide