Biology subjects

Kershaw, S.

Publications and source records attributed to Kershaw, S..

3 recordsLinked to original sources

bioRxiv2024

Sponges of the Lower Greensand Group (Lower Cretaceous) of England; a revision

Sponges of the Lower Greensand Group (LGS) are well preserved, and occur in sediments of a sandy matrix. Abundant in the Faringdon Sponge Gravel Member (FSG), these sponges, mostly Calcareans are found in Oxfordshire, with notable preservation at Little Coxwell quarries. Classical researchers described sponges and spicules from the LGS, including Lhuyd (considered to have been the first to publish illustrations of LGS sponges), Sharpe, Sowerby and Parkinson. In addition to the FSG, the Folkestone, Hythe, and Atherfield Clay formations within the LGS also contain sponge remains, including spicules as well as whole sponge fossils. These sponges include mostly samples from traditional sponge class Calcarea and a taxon of Hexactinellida; Altogether, the sponge assemblage developed in warm seas of the Lower Cretaceous, and display diverse shapes of sponge bodies and robust spicules. This study provides descriptions of common species following updated Porifera classification and recent sponge taxonomy research, illustrated with specimens from the Natural History Museum, London (NHM) and British Geological Survey (BGS) collections. The following taxa are recorded and described: 1) Calcareans: Barroisia anastomosans (Parkinson, 1811), Barroisia clavata (Keeping, 1883), Barroisia irregularis (Hinde, 1884), Dehukia crassa (de Fromentel, 1861), [Elasmoierea] faringdonensis (Mantell, 1854), [Elasmoierea] mantelli (Hinde, 1884), Peronidella gillieroni (Loriol, 1869), Peronidella prolifera (Hinde, 1884), Peronidella ramose (Roemer, 1839), Oculospongia dilatate (Roemer, 1864), Tremospongia pulvinaria (Goldfuss, 1826), Raphidonema contortum (Hinde, 1884), Raphidonema porcatum (Sharpe, 1854), Raphidonema farringdonensis (Sharpe, 1854), Raphidonema macropora (Sharpe, 1854), Raphidonema pustulatum Hinde, 1884, Endostoma foraminosa (Goldfuss, 1829); 2) Hexactinellids: Lonsda contortuplicata Lonsdale, 1849.

paleontology↗

bioRxiv2024

Devonian stromatoporoid historical collections in the Natural History Museum, London (UK): redescription, taxonomic revision and implications for stromatoporoid global paleobiogeography

Devonian stromatoporoid collections in the Natural History Museum, London (UK) have been deposited for over 100 years. The characteristics and systematic position of these specimens, however, have received little attention. In this study, a total of 307 Devonian stromatoporoid specimens comprising material documented by Nicholson (1886-1892) from the UK, Germany, United States, and Canada, plus specimens described by Ripper (1933, 1937a, b, c) from Australia, were re-examined. Overall, 50 species belonging to 29 genera were systematically redescribed based on recent progress, mainly including Actinostroma, Petridiostroma, Stictostroma, Pseudotrupetostroma, Parallelopora. Three-dimensional reconstructions of the type genus are illustrated following the earlier works of Stearn (1966) and Cockbain (1984). The reconstructed skeletons reveal stromatoporoid architectural patterns, crucial for enhancing understanding and revision of stromatoporoid identification. This study underscores the significance of three-dimensional reconstruction in taxonomic research on stromatoporoid. The NHMUK material is combined with data from publications and the Paleobiology Database (PBDB) to perform a network analysis of the global occurrence of Devonian stromatoporoids at the generic level; this reveals a close relationship of global stromatoporoid fauna during the Early Devonian, indicating a widespread distribution, despite this interval being regarded as a time of global stromatoporoid contraction. The Middle Devonian assemblage shows a much higher cosmopolitan occurrence in the context of the subsequent Eifelian-Givetian global stromatoporoid proliferation, consistent with the known pattern from other studies of Middle Devonian stromatoporoids. Overall, the NHMUK collections are a valuable resource to help understand the global occurrence of Devonian stromatoporoids.

paleontology↗

bioRxiv2022

Keratose sponges in ancient carbonates - a problem of interpretation

Increasing current interest in sponge fossils includes numerous reports of diverse vermicular and peloidal structures interpreted as keratose sponges in Neoproterozoic to Mesozoic carbonates and in various open marine to peritidal and restricted settings. Reports of their occurrence are fundamental and far-reaching for understanding microfacies and diagenesis where they occur; and fossil biotic assemblages, as well as wider aspects of origins of animals, sponge evolution/ecology and the systemic recovery from mass extinctions. Keratose sponges: 1) have elaborate spongin skeletons but no spicules, thus lack mineral parts and therefore have poor preservation potential so that determining their presence in rocks requires interpretation; and 2) are presented in publications as interpreted fossil structures almost entirely in two-dimensional (thin section) studies, where structures claimed as sponges comprise diverse layered, network, particulate and amalgamated fabrics involving calcite sparite in a micritic groundmass. There is no verification of sponges in these cases and almost all of them can be otherwise explained; some are certainly not correctly identified. The diversity of structures seen in thin sections may be reinterpreted to include: a) meiofaunal activity; b) layered, possibly microbial (spongiostromate) accretion; c) sedimentary peloidal to clotted micrites; d) fluid escape and capture resulting in birdseye to vuggy porosities; and e) molds of siliceous sponge spicules. Without confirmation of keratose sponges in ancient carbonates, interpretations of their role in ancient carbonate systems, including facies directly after mass extinctions, are unsafe, and alternative explanations for such structures should be considered. This study calls for greater critical appraisal of evidence, to seek confirmation or not, of keratose sponge presence. (259/300 max, for Sedimentology)

paleontology↗