Portishead Bed 10 (Devonian of the United Kingdom)

Where: Somerset, United Kingdom (51.5° N, 2.8° W: paleocoordinates 19.4° S, 0.5° W)

• coordinate based on nearby landmark

When: Old Red Sandstone Formation, Famennian (372.2 - 358.9 Ma)

• Bed 10, Woodhill Bay Section

Environment/lithology: "floodplain"; fine-grained, micaceous sandstone and siltstone

• Wallis (1928) suggested that the environment of deposition was a large river system, with lagoons forming along the coast. Pick (1964) further suggested that the beds were deposited on

•wide alluvial floodplains by rivers constantly altering their flow direction, evidenced by abundant cross-stratification and cross-cutting of channels. As well as the finer sedimentsdeposited on short-lived inter-fluvial lakes and mudflats, coarser deposits were formed by fast-flowing streams (Pick 1964). Measurements of palaeocurrent direction at Portishead show a preferred south-easterly

•direction of flow, with occasional transitions to a northwesterly flow, thought to be because of the meandering of streams that changed course or joined the main river atdifferent angles (Pick 1964). The eurypterids, found in the finer sandstone layers, are mostly concentrated into one side of a single bed that may represent an oxbow lake.

• The fossiliferous horizons consist of micaceous siltstonesand fine-grained micaceous sandstones. The siltstones are finely laminated, while the sandstones often display trough cross-bedding and cut into underlying beds. Tool marks on the base of the sandstone beds attest to their high energy of deposition

Size class: macrofossils

Preservation: mold/impression, original chitin

Primary reference: J.C. Lamsdell, S.J. Braddy, and O.E. Tetlie. 2009. Redescription of Drepanopterus abonensis (Chelicerata: Eurypterida: Stylonurina) From The Late Devonian Of Portishead, UK. Palaeontology 52:1131-1139 [R. Plotnick/R. Plotnick]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 232123: authorized by Roy Plotnick, entered by Roy Plotnick on 25.10.2023

Creative Commons license: CC BY (attribution)

Taxonomic list

Show authors, comments, and common names
Arachnida
 Scorpiones - Praearcturidae
Praearcturus sp.
Praearcturus sp. Woodward 1871 scorpion
Euchelicerata
 Eurypterida - Drepanopteridae
Drepanopterus abonensis
Drepanopterus abonensis Simpson 1951 eurypterid
Malacostraca
 Archaeostraca - Ceratiocarididae
Ceratiocaris sp.
Ceratiocaris sp. M'Coy 1849
Placodermi
 Antiarchiformes - Bothriolepididae
Bothriolepis sp.
Bothriolepis sp. Eichwald 1840 armour-plated fish
 Phyllolepida - Phyllolepidae
Phyllolepis sp.
Phyllolepis sp. Agassiz 1843 armour-plated fish
 Arthrodira - Groenlandaspididae
Groenlandaspis sp.
Groenlandaspis sp. Heintz 1932 armour-plated fish
 Arthrodira - Coccosteidae
Coccosteus sp.
Coccosteus sp. Agassiz 1843 armour-plated fish
Osteichthyes
 Dipnomorpha - Holoptychiidae
"Holoptychius giganteus" = Gyrolepis (Holoptychius) giganteus, Holoptychius nobilissimus
"Holoptychius giganteus" = Gyrolepis (Holoptychius) giganteus Agassiz 1843 lobe-finned fish
Holoptychius nobilissimus Agassiz 1835 lobe-finned fish
 Ichnofossils -
Cochlichnus sp., Diplocraterion sp.
Cochlichnus sp. Hitchcock 1858
Diplocraterion sp. Torell 1870