title: Sponge grade body fossil with cellular resolution dating 60 Myr before the Cambrian.
abstract: An extraordinarily well preserved, 600-million-year (Myr)-old, three-dimensionally phosphatized fossil displaying multiple independent characters of modern adult sponges has been analyzed by SEM and synchrotron X-ray tomography. The fossilized animal (Eocyathispongia qiania gen. et sp. nov.) is slightly more than 1.2 mm wide and 1.1 mm tall, is composed of hundreds of thousands of cells, and has a gross structure consisting of three adjacent hollow tubes sharing a common base. The main tube is crowned with a large open funnel, and the others end in osculum-like openings to the exterior. The external surface is densely covered with flat tile-like cells closely resembling sponge pinacocytes, and this layer is punctuated with smaller pores. A dense patch of external structures that display the form of a lawn of sponge papillae has also survived. Within the main funnel, an area where features of the inner surface are preserved displays a regular pattern of uniform pits. Many of them are surrounded individually by distinct collars, mounted in a supporting reticulum. The possibility cannot be excluded that these pits are the remains of a field of choanocytes. The character set evinced by this specimen, ranging from general anatomy to cell type, uniquely indicates that this specimen is a fossil of probable poriferan affinity. So far, we have only this single specimen, and although its organized and complex cellular structure precludes any reasonable interpretation that its origin is abiogenic, confirmation that it is indeed a fossilized sponge will clearly require discovery of additional specimens.
authors.affiliation: State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China;
authors.forename: Zongjun
authors.initials: Z
authors.lastname: Yin
authors.affiliation: State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China; myzhu@nigpas.ac.cn.
authors.forename: Maoyan
authors.initials: M
authors.lastname: Zhu
authors.affiliation: Division of Biology, California Institute of Technology, Pasadena, CA 91125;
authors.forename: Eric H
authors.initials: EH
authors.lastname: Davidson
authors.affiliation: Department of Earth Sciences, University of Southern California, Los Angeles, CA 90089; and.
authors.forename: David J
authors.initials: DJ
authors.lastname: Bottjer
authors.affiliation: State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China;
authors.forename: Fangchen
authors.initials: F
authors.lastname: Zhao
authors.affiliation: European Synchrotron Radiation Facility, Grenoble 38000, France.
authors.forename: Paul
authors.initials: P
authors.lastname: Tafforeau
mesh_terms: D000818:Animals; D005075:Biological Evolution; D005580:Fossils; D023281:Genomics; D005844:Geology; D008855:Microscopy, Electron, Scanning; D010802:Phylogeny; D011161:Porifera / Q000235:genetics / Q000648:ultrastructure*; D013499:Surface Properties; D017356:Synchrotrons; D014056:Tomography, X-Ray
keywords: Doushantuo Formation; Precambrian; metazoan phylogeny; sponge fossil; synchrotron X-ray tomography