Discovery of 505-million-year old chitin in the basal demosponge Vauxia gracilenta

Sponges are probably the earliest branching animals, and their fossil record dates back to the Precambrian. Identifying their skeletal structure and composition is thus a crucial step in improving our understanding of the early evolution of metazoans. Here, we present the discovery of 505-million-year-old chitin, found in exceptionally well preserved Vauxia gracilenta sponges from the Middle Cambrian Burgess Shale. Our new findings indicate that, given the right fossilization conditions, chitin is stable for much longer than previously suspected. The preservation of chitin in these fossils opens new avenues for research into other ancient fossil groups

An enigmatic, possibly chemosymbiotic, hexactinellid sponge from the early Cambrian of South China

Six specimens of a strongly curved, cylindrical hexactinellid sponge have been recovered from the Tommotian– Atdabanian Hetang Biota of South China, and are described as Decumbispongia yuani gen. et sp. nov. The robust, thick−walled sponge shows no evidence of an osculum or basal structures, and the body form is inconsistent with an upright, filter−feeding life position. Interpretations as a detritivore feeding by amoeboid extensions, or as a facultative chemosynthetic symbiosis of sponge and bacteria are considered. The latter interpretation is preferred due to the highly constrained body shape, and the body form is interpreted from this perspective. The species indicates that Cambrian sponges occupied at least some autecological niches that appear to have been vacant since that time

Sponge spicule assemblages from the Cambrian (Series 2?3) of North Greenland (Laurentia) : systematics and biogeography

Isolated microscopic spicules from disarticulated scleritomes demonstrate the presence of a diverse sponge fauna otherwise not evident from the macrofossil record in carbonate successions deposited during the un-named Cambrian Series 2 and Cambrian Series 3 (Miaolingian) in North Greenland. Most of the spicule morphotypes are not recognised from faunas of articulated sponges known from contemporaneous siliciclastic strata elsewhere. Assemblages are described in terms of four Cambrian stages and contain numerous spicule morphotypes not previously recorded from Laurentia. Many of the spicules can be correlated worldwide, however, extending current knowledge of the biogeographic distribution of sponge spicule-based taxa in the Cambrian. In particular, similar Cambrian Stage 4 (Series 2) and Miaolingian assemblages (Wuliuan, Drumian and Guzhangian stages) faunas are recorded from tropical palaeolatitudes in Australia, South China, Siberia and Laurentia, although this may in part reflect a methodology focused on the preparation of the carbonate samples that dominate these successions. New spicule-based taxa: Eiffelia floriformis n. sp., Australispongia? inuak n. sp., Celtispongia dorte n. gen. n. sp., Sanningasoqia borealis n. gen. n. sp., Speciosuspongia inughuitorum n. sp., Sulukispicula gelidae n. gen. n. sp