Chapter 8 Cambrian, Ordovician and Silurian non-stromatoporoid Porifera

Abstract

The Cambrian, Ordovician and Silurian distributions of non-stromatoporoid sponges are reviewed. The earliest Cambrian faunas contain mostly hexactinellids, with protomonaxonids dominating middle Cambrian assemblages. There are no obvious palaeobiogeographical patterns, with many genera being found widely. Vauxiids, lithistids and heteractinids are apparently confined to low latitudes, but this may be due to a poor fossil record. Most known Ordovician faunas are from low latitudes, although some high-latitude faunas are known, which contain reticulosan hexactinellids and protomonaxonids. There is some division of faunas within Laurentia, into eastern and western provinces, with the western assemblage extending across low northern latitudes during the Late Ordovician. During the Silurian Period, sponge diversity was very low during the Llandovery Epoch, probably partly owing to lack of habitat for taxa restricted to carbonate facies, and also because of sampling bias. There was a dramatic increase in diversity through the Silurian Period, mostly owing to an apparent diversification in the demosponges; however, there are many ghost lineages, indicating that their fossil record is poorly known. Non-lithistid sponges are very poorly known, with few recorded outside Euramerica. The currently available data for Early Palaeozoic sponges are too incomplete to allow any reliable palaeobiogeographical inferences.Supplementary material:the compilation of Silurian sponge occurrences is available at:http://www.geolsoc.org.uk/SUP18666.

Llandovery microfossils and microfacies of the Hýskov section, Prague Basin

“…The occurrence of hexactinellid sponge spicules in such an environment is rather surprising, as more quiet-water facies are thought to be the typical environment for sponges. In general, the record of Early Palaeozoic sponges is very sparse (Muir et al 2013), and only a handful of studies report their occurrence in a shallow, agitated environment (Botting 2005, Beresi et al 2006, Rhebergen and Botting 2014. Except for samples from the levels 0 cm, 260-280 cm (tuffaceous layer) and 340-350 cm, sponge spicules were among the most abundant components.…”

Ordovician sponges from the Lenoir Limestone, Tennessee: new evidence for a differential sponge distribution along the margins of Laurentia

“…The first attempt to analyze the global distribution of Ordovician sponges, particularly those along the Laurentian margins, was performed by Carrera and Rigby (1999). Additional studies focusing on Ordovician sponge diversification patterns also incorporated paleobiogeographic information (Carrera and Rigby, 2004; Carrera and Botting, 2008; Muir et al, 2013). Updated information published subsequently confirms the overall paleobiogeographic pattern for sponge distribution in the Laurentian paleocontinent.…”

“…Updated information published subsequently confirms the overall paleobiogeographic pattern for sponge distribution in the Laurentian paleocontinent. Most of the more recent Ordovician sponge taxonomic studies are concentrated in areas outside of North America such as China, Korea, Morocco, and Wales with new data on protomonaxonid and orchoclad demosponges and hexactinellids (Muir et al, 2013; Botting and Muir, 2018 and references therein).…”

An outline of the distribution and diversity of Porifera in the Ordovician Builth Inlier (Wales, UK)

“…In the Burgess Shale they are second only to arthropods in species diversity and abundance of individuals (Caron and Jackson, 2008); in the arthropod-dominated Chengjiang Biota, sponges make up approximately 12% of the total generic diversity (Dornbos and Chen, 2008); and they are similarly important in many of the other Cambrian Burgess Shale-type faunas. During the Cambrian, individual sponge taxa were widely distributed, with many genera and even species shared across widely separated palaeocontinents (Carrera and Botting, 2008;Muir et al, 2013). However, despite some extensive studies that might suggest a reasonable fossil record (Carrera and Botting, 2008) our understanding of Ordovician and Silurian sponges remains poor, with little understanding of their distribution patterns or true diversity .…”