Article Figures & Data
Figures
- Fig. 1.
Provenance and palaeogeography. (a) Welsh Borderland location of the Herefordshire Lagerstätte with regional geology. (b) The volcanic ash (bentonite), with concretions in situ, in contact with Coalbrookdale Formation shales above. (c) Typical concretion, 6 × 4 cm, concentrically weathered, lacking the blue-grey-hearted centre of calcium carbonate that is present in partially weathered examples, and incorporating an eccentric specimen of the aplacophoran Acaenoplax. (d) Local stratigraphy of the Dolyhir–Presteigne area. Radiometric dates are those given in Cohen et al. (2013, updated 2018), the International Commission on Stratigraphy (ICS) Chronostratigraphic Chart. Cramer et al. (2012) give marginally different radiometric dates for some of the boundaries based on sampling from Gotland and the West Midlands, UK, for example 429.5 Ma for the Sheinwoodian–Homerian boundary. However, the majority margin of error on these dates (±0.7 Ma) provides overlap with the dates given in the ICS Chronostratigraphic Chart. (e) Welsh Basin palaeogeography at approximately the Sheinwoodian–Homerian boundary (modified from Cherns et al. 2006, fig. 4.13a). (f) Eastern Laurussian palaeogeography during the Wenlock (modified from Cocks & Torsvik 2005, fig. 9).
- Fig. 2.
(a) Faunal composition of the major groups of the Herefordshire Lagerstätte. Percentage abundance is based on number of specimens (n = 3670); some specimens as yet undescribed and unassigned at species level are included, and radiolarians are excluded. (b) Panarthropod faunal composition of the Herefordshire Lagerstätte. Percentage abundance is based on number of specimens (n = 982). The chelicerate Offacolus is by far the best represented species (833 specimens = 84.8% of the total number); all other species are represented by less than 10 specimens each (= less than 1%), except for the mandibulate Tanazios (88 specimens = 9.0%) and the malacostracan Cinerocaris (18 = 1.8%).
- Fig. 3.
Examples of Herefordshire animals on the split surface of concretions. (a) Longitudinal horizontal section of the chelicerate Offacolus kingi. (b) Longitudinal subcentral section of the edrioasteroid Heropyrgus disterminus. (c) Longitudinal subcentral section of the sponge Carduispongia pedicula. (d) Longitudinal subcentral section of the aculiferan Acaenoplax hayae. (a) and (c) show grey- to light blue-coloured carbonate-rich matrix of the concretion, within and around the fossil; (b) and (d) show orange - to yellow-coloured matrix of the concretion, indicating weathered (leached) examples. Scale bars are all 1 mm.
- Fig. 4.
Herefordshire Lagerstätte species. (a) Colymbosathon ecplecticos, valves removed, lateral view. (b) Nymphatelina gravida, left valve removed, posterolateral view. (c, f) Offacolus kingi, dorsal, ventrolateral views (see Fig. 3a). (d, e, g, i) Dibasterium durgae, ventrolateral stereo-pair, dorsal view; chelicerae (first appendages), lateral view; prosomal area and anterior part of opisthosoma, ventral view. (h) Aquilonifer spinosus, dorsal view. (j) Drakozoon kalumon, ventral view. (k) Bethia serraticulma, with attached Drakozoon kalumon and ?atrypide brachiopod, lateral view. (l, m) Kulindroplax perissokomos, lateral, dorsal views. (n, o) Rhamphoverritor reduncus, attached juvenile, free swimming stage, lateral views. (p) Invavita piratica, lateral view. (q, r) Nymphatelina gravida, with valves, and valves removed, with an attached and an internal specimen of Invavita piratica, lateral views. (s, t) Acaenoplax hayae, anterior part of body, dorsolateral view; main and posterior parts of body, dorsolateral view (see Fig. 3d). (u, v) Cladograms depicting competing molluscan phylogenies (simplified from Wanninger & Wollesen 2018): (u) ‘Testaria’ hypothesis, one of several phylogenetic models in which aplacophorans are primitive with respect to all other molluscs; (v) ‘Aculifera’ hypothesis, in which aplacophorans and polyplacophorans form a sister clade (Aculifera) to all other molluscs (Conchifera). Scale bars are all 500 µm.
- Fig. 5.
Herefordshire Lagerstätte species. (a, b) Thanahita distos, dorsal, right lateral views. (c, d) Cinerocaris magnifica, right lateral, posterior ventrolateral views. (e) Enalikter aphson, dorsal view. (f–i) Bdellacoma sp., isolated example of pedicellaria with one valve removed, internal, lateral views; pedicellariae attached to arm; portion of arm with spines and podia, sub-adoral view. (j, k) Heropyrgus disterminus, dorsal, lateral views (see Fig. 3b). (l, m) Cascolus ravitis, anterolateral, dorsal views. (n, o) Haliestes dasos, dorsal, anterolateral view. (p, t) Tanazios dokeron, dorsal, anterolateral views. (q) Sollasina cthulhu, aboral view. (r, w) Xylokorys chledophilia, ventrolateral, dorsal views. (s) Kenostrychus clementsi, anterolateral view. (u) Spirocopia aurita, valves removed, right lateral view. (v) Platyceras sp., anterior part of shell removed, view from position normal to viscera. (x) Inanihella sagena. (y) Carduispongia pedicula, lateral view (see Fig. 3c). (z) Nasunaris flata, right valve removed, lateral view. (zz) Pauline avibella, right lateral view. Scale bars are all 500 µm.
- Fig. 6.
Stratigraphic occurrence of Silurian Lagerstätten. The radiometric dates are those given in Cohen et al. (2013, updated 2018), the International Commission on Stratigraphy (ICS) Chronostratigraphic Chart.
- Fig. 7.
Ecological types and percentage abundance based on number of species (n = 63). It includes the four radiolarian species, and some species belonging to other major groups that are as yet undescribed and unassigned at species level.
Tables
Sponges Carduispongia pedicula (Nadhira et al. 2019; Fig. 5y) Some 20 other species (uninvestigated) Cnidarians ? Hydroid (uninvestigated colonial organism) Coral (uninvestigated) Brachiopods Bethia serraticulma (Sutton et al. 2005a; Fig. 4k) At least two other brachiopod species (both uninvestigated), one of them a lingulid Lophophorate indet. Drakozoon kalumon (Sutton et al. 2010; Fig. 4j) Annelids Kenostrychus clementsi (Sutton et al. 2001c; Fig. 5s) Molluscs Aplacophorans Acaenoplax hayae (Sutton et al. 2001a; Fig. 4s and t) Kulindroplax perissokomos (Sutton et al. 2012a; Fig. 4l and m) Bivalvia Praectenodonta ludensis Reed, 1931 (Fu 2016) Gastropods Platyceras? sp. (of Sutton et al. 2006; Fig. 5v) A high spired species (uninvestigated) Cephalopods Nautiloids (uninvestigated) Panarthropods Lobopodians Thanahita distos (Siveter et al. 2018b; Fig. 5a and b) Megacheirans Enalikter aphson (Siveter et al. 2014a, 2015a; Fig. 5e) Pycnogonids Haliestes dasos (Siveter et al. 2004; Fig. 5n and o) Chelicerates Offacolus kingi (Orr et al. 2000; Fig. 4c and f) Dibasterium durgae (Briggs et al. 2012; Fig. 4d, e, g and i) Trilobites Dalmanites sp. (uninvestigated) Tapinocalymene sp. (uninvestigated) Marrellomorphs Xylokorys chledophilia (Siveter et al. 2007b; Fig. 5r and w) Mandibulates Aquilonifer spinosus (Briggs et al. 2016; Fig. 4h) Tanazios dokeron (Siveter et al. 2007d; Fig. 5p and t) Crustaceans Malacostracans Cinerocaris magnifica (Briggs et al. 2003; Fig. 5c and d) Cascolus ravitis (Siveter et al. 2017; Fig. 5l and m) Cirripedes Rhamphoverritor reduncus (Briggs et al. 2005; Fig. 4n and o) Ostracods - Myodocopes Colymbosathon ecplecticos (Siveter et al. 2003; Fig. 4a) Nymphatelina gravida (Siveter et al. 2007c; Fig. 4b, q and r) Nasunaris flata (Siveter et al. 2010; Fig. 5z) Pauline avibella (Siveter et al. 2013; Fig. 5zz) Spiricopia aurita (Siveter et al. 2018a; Fig. 5u) - Podocopes and palaeocopes Fragments of unidentified species belonging to these ostracod groups have been recovered from acid residues Pentastomids Invavita piratica (Siveter et al. 2015b, Fig. 4p, q and r) Echinoderms Asteroids Bdellacoma sp. (of Sutton et al. 2005b; Fig. 5f–i) Edrioasteroids Heropyrgus disterminus (Briggs et al. 2017; Fig. 5j and k) Crinoids (uninvestigated sp.) Ophiocistioids Sollasina cthulhu (Rahman et al. 2019; Fig. 5q) Hemichordates Pterobranchs Graptoloids (uninvestigated) Dendroids? (uninvestigated) Radiolarians Inanihella sagena (Siveter et al. 2007a; Fig. 5x) Inanihella sp. (of Siveter et al. 2007a) Haplentactinia armista (Siveter et al. 2007a) Parasecuicollacta hexactinia (Won et al. 2002) Mazuelloids Fragments of unidentified mazuelloid species have been recovered from acid residues The relevant primary reference is given after the species name. Other relevant references are given throughout the text.
- Article
- Abstract
- Locality, age and palaeogeographical setting
- Taphonomy
- Releasing the information from the fossils
- Unexpected character combinations and a possible role for evolutionary development
- Extended stratigraphic ranges and the calibration of molecular clocks
- Mode of life and palaeoecology
- Why is the Herefordshire Lagerstätte apparently unique?
- Acknowledgements
- Funding
- Author contributions
- References
- Figures & Data
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