Lower Allt Ddu trilobites (Ordovician of the United Kingdom)

Where: Wales, United Kingdom (52.9° N, 3.6° W: paleocoordinates 52.2° S, 18.4° W)

• coordinate based on nearby landmark

• local area-level geographic resolution

When: Diplograptus multidens graptolite zone, Allt Ddu Formation (Lower Bala Group), Soudleyan (457.5 - 455.8 Ma)

• lower assemblage zone

• member-level stratigraphic resolution

Environment/lithology: marine; lithified, bioturbated, blue, silty mudstone and lithified, fine-grained siltstone

• Allt Ddu: monotonous series of dark blue silty mudstones with fine siltstones commonly disposed in small-scale cross- and ripple- lamination...greatly disturbed by burrowing organisms and bedding is poorly developed except in the coarser beds [Bassett et al 1996]

Size class: macrofossils

Preservation: mold/impression

Reposited in the BMNH

Primary reference: H. B. Whittington. 1968. The Ordovician trilobites of the Bala Area, Merioneth. Part IV. Monograph of the Palaeontographical Society 122(520):93-138 [M. Hopkins/M. Hopkins]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 188588: authorized by Melanie Hopkins, entered by Melanie Hopkins on 08.09.2017

Creative Commons license: CC BY (attribution)

Taxonomic list

 Phacopida - Homalonotidae
Brongniartella sp. Reed 1918 trilobite
 Phacopida - Calymenidae
Flexicalymene (Reacalymene) limba Shirley 1936 trilobite
 Asaphida - Trinucleidae
Broeggerolithus broeggeri Bancroft 1929 trilobite
 Orthotetida - Triplesiidae
 Strophomenida - Sowerbyellidae
"Sowerbyella sericea" = Sowerbyella (Sowerbyella) sericea
"Sowerbyella sericea" = Sowerbyella (Sowerbyella) sericea Sowerby 1839
subspecies permixta
 Strophomenida - Rafinesquinidae
Leptaena ventricosa Williams 1963
"Macrocoelia prolata" = Colaptomena expansa prolata Williams 1963
 Orthida - Dalmanellidae
Dalmanella sp. Hall and Clarke 1892
 Orthida - Harknessellidae
 Orthida - Heterorthidae
 Orthida - Plaesiomyidae
Dinorthis berwynensis Whittington 1938
 Lingulida - Obolidae