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A Middle Ordovician Burgess Shale-type fauna from Castle Bank, Wales (UK)


Burgess Shale-type faunas are critical to our understanding of animal evolution during the Cambrian, giving an unrivalled view of the morphology of ancient organisms and the ecology of the earliest animal-dominated communities. Rare examples in Lower Ordovician strata such as the Fezouata Biota illustrate the subsequent evolution of ecosystems but only from before the main phase of the Great Ordovician Biodiversification Event. Later Ordovician Konservat-Lagerstätten are not directly comparable with the Burgess Shale-type faunas as they do not represent diverse, open-shelf communities, limiting our ability to track ecological development through the critical Ordovician biodiversification interval. Here we present the Castle Bank fauna: a highly diverse Middle Ordovician Burgess Shale-type fauna from Wales (UK) that is directly comparable with the Burgess Shale and Chengjiang biotas in palaeoenvironment and preservational style. The deposit includes animals with morphologies similar to the iconic Cambrian taxa Opabinia, Yohoia and Wiwaxia, combined with early examples of more derived groups such as barnacles. Many taxa such as kinorhynchs show the small sizes typical of modern faunas, illustrating post-Cambrian miniaturization. Castle Bank provides a new perspective on early animal evolution, revealing the next chapter in ecosystem development following the Chengjiang, Burgess Shale and Fezouata biotas.

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Fig. 1: Location and stratigraphy.
Fig. 2: Middle Ordovician fossils from the Castle Bank Biota.
Fig. 3: Preservational modes in the Castle Bank Biota.
Fig. 4: Examples of fine detail preservation in Castle Bank Biota fossils.
Fig. 5: Reconstruction of the Castle Bank community.

Data availability

Numerical data sharing is not applicable to this paper as no datasets were generated or analysed during the current study. Figured material has been deposited in Amgueddfa Cymru—Museum Wales, Cardiff, UK (prefix NMW) and the Nanjing Institute of Geology and Palaeontology, Nanjing, China (prefix NIGP), with SCF microfossils deposited in the Museum of Evolution, Uppsala, Sweden (prefix PMU). To protect the site and at the request of the landowner, locality details are not being published. All necessary information has been deposited with the specimens in Amgueddfa Cymru—Museum Wales, where it is available to bona fide researchers.


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The support of the landowners is gratefully acknowledged, as are all contributors to a crowdfunding appeal (including a Holloway Bursary from the Warwickshire Geological Conservation Society, UK) that allowed the purchase of photomicroscope equipment for use by J.P.B. and L.A.M. Reconstruction (Fig. 5) drawn by D.H. Yang, Nanjing Institute of Geology and Palaeontology. L. Parry (University of Oxford, UK) provided helpful comments on some of the material. J.P.B. and L.A.M. are funded by Chinese Academy of Sciences PIFI fellowships (2020VCB0013 and 2018VCB0014, respectively), Y.Z. and J.M. by the National Natural Science Foundation of China (NSFC: 42030510, 41972019) and the Strategic Priority Research Program (B) of the Chinese Academy of Sciences (XDB26000000) and S.P. by a Herchel Smith Postdoctoral Fellowship (University of Cambridge, UK). L.M.E.M. acknowledges the support of Amgueddfa Cymru-National Museum Wales and thanks C. Howells for providing accession numbers for the Castle Bank specimens. B. Slater (Uppsala University, Sweden) advised on interpretation of some SCF material. We thank Y. Fang (NIGPAS, CAS) for assistance with the SEM–EDS analysis and S. Jones (Llandrindod) and G. Steel (Huntington, Herefordshire, UK) for comments on the readability of the paper. This article is a contribution to IGCP project 653 ‘The onset of the Great Ordovician Biodiversification Event’ and to IGCP project 735 ‘Rocks and the rise of Ordovician life: filling knowledge gaps in the Early Palaeozoic biodiversification’.

Author information

Authors and Affiliations



This paper was written by J.P.B. and L.A.M., with contributions from all authors. The fauna was discovered and fieldwork conducted by J.P.B. and L.A.M., with interpretation of specimens by J.P.B., L.A.M., S.P. and L.M.E.M. Acid dissolution and analysis/interpretation of SCFs was conducted by E.W. and S.W. Electron microscopy was carried out by S.W. and J.M. Funding was procured by J.M., Y.Z., J.P.B. and L.A.M. The project was conceived and organized by J.P.B. and L.A.M.

Corresponding authors

Correspondence to Joseph P. Botting or Junye Ma.

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The authors declare no competing interests.

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Nature Ecology & Evolution thanks Julien Kimmig, Nigel Hughes and James Schiffbauer for their contribution to the peer review of this work. Peer reviewer reports are available.

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Extended data

Extended Data Fig. 1 Sedimentological log of the Castle Bank locality, and distribution of exceptional preservation.

a, log of the Castle Bank quarry showing lithological sequence and notes on occurrence of different faunal assemblages; b, ecological log of the two-metre-thick interval of exceptional preservation, showing changing proportions of the graptolite Didymograptus murchisoni to the phosphatic brachiopod Apatobolus micula within the sequence, and correlation with extensive occurrence of soft-tissue preservation (concentrations of graptolites represent generally slower deposition); c, lithological log of the 20-cm-thick interval with Burgess Shale-type preservation, showing higher frequency of event beds (darker grey lenses and layers) that contain Burgess Shale-type preservation; d, polished vertical section through an event bed at level A3, with scale bar 1 mm.

Extended Data Fig. 2 Additional arthropods from the Castle Bank Fauna.

a–d, stem-group xiphosuran from level A0 with detail view of anterior interpretative diagram (b, excluding whip-like posterior that may be an overlain structure), including robust anterior appendages (ap) (enlarged in c), prosoma (shaded, slightly rotated) with eye ridges (ey), mesosoma (meso), segmented metasoma (meta) and base of telson (tel); note also polygonal sculpture on prosoma, visible in d, the counterpart, with second eye ridge arrowed (NMW.2021.3 G.9); e–f, elongate arthropod with cephalocarid-like characters (NMW.2021.3 G.14) with interpretative drawing (based also on additional lighting variations) distinguishing cephalon (ce), thorax with ten segments (th1–10), abdomen with approximately 12 segments (ab1–12) and forked telson (t); g, h, hexapod-like arthropod (as Fig. 1b) with enhanced contrast and interpretative diagram (h), highlighting body regions, three visible limbs (numbered, and in different colours), possible superimposed antenna (ant?) and possible mandible (m?) (NMW.2021.3 G.11); i, j, pair of barnacles, the right attached to the left, with explanatory drawing (ped: peduncle in anterior/posterior view, and broader in lateral view; car: carina; tg: tergum; sc: scutum; ci: cirri) (NMW.2021.3 G.66); k, bivalved arthropod with robust frontal appendages, tail fan and posteriorly spined carapace (NMW.2021.3G.13). Scale bars 1 mm.

Extended Data Fig. 3 Additional new sponge taxa from the Castle Bank fauna.

a, small, complex hexactinellid sponge (level uncertain) with euplectellid-like skeletal strands (NMW.2021.3 G.35); b, tall cylindrical hexactinellid with hypodermal pentactins and rossellid-like architecture (NIGP175889); c, complex conico-cylindrical hexactinellid (NMW.2021.3 G.36); d, stalked ascosponge (new genus) from level A8 with small soft-tissue region (top) supported by long basalia (NMW.2021.3 G.37); e, Teganiella sp. from level A6, the first record from outside the Americas (NMW.2021.3 G.38); f, the most abundant sponge species at the site, a small conical ascosponge from level A9 (NMW.2021.3 G.39i); g, complex hexactinellid (NMW.2021.3 G.40); h, relatively large rossellid-like sponge with abundant prostalia (NMW.2021.3 G.39ii). Scale bars 1 mm.

Extended Data Fig. 4 Deuterostomes from the Castle Bank fauna.

a–c, dendroid graptolite Dictyonema sp. with zooids (NMW.2021.3 G.40); a, cross-polarized light to highlight tubarium; b, plane-polarized light, with dark spots being zooids within thecae; c, detail of zooid (boxed in b) with evidence for cephalic shield (cs) and lophophore (loph) (NMW.2021.3 G.41); d, multi-branched benthic graptolite (NMW.2021.3 G.43); e–g, overall view (with interpretative drawing, f) and detail of body region of hemichordate with lophophore (loph) of two main tentacles and short lateral projections, fusellar-banded tube (tub), and reticulate holdfast region (ho) (NMW.2021.3 G.44); h, pair of Dendrocystites-like solutans from uncertain level (NMW.2021.3 G.45); i, undescribed asterozoan (NMW.2021.3 G.67); j, conodont (NMW.2021.3 G.95); k, bedding plane assemblage of conodonts (NMW.2021.3 G.96). Scale bars 1 mm (except c and k: 0.5 mm).

Extended Data Fig. 5 Vermiform organisms of the Castle Bank Biota.

a–c, unidentified spinose worm with complex jaw apparatus, from level A1, boxed details enlarged in b–c (NMW.2021.3 G.94); b, detail of jaw apparatus; c, anterior margin with tentacles (arrowed); d, e, probable priapulid with narrow cylindrical tube, and extruded soft body (e) (NMW.2021.3 G.97); f–h, archaeopriapulid with complex proboscis (g) showing scalids and multiple zones of pharyngeal teeth (h, labelled A–D) (NMW.2021.3 G.19); i–j, one of several species of kinorhynch-like fossils with proboscis (p), neck (n) with projecting filaments, and eleven plated trunk segments with longitudinal, projecting bristles (NMW.2021.3 G.69); k, palaeoscolecid worm with transverse rows of large plates (NMW.2021.3 G.88); l–m, palaeoscolecid with minute plates, enlarged with cross-polarization in m (NMW.2021.3 G.89). Scale bars 1 mm except for g (0.25 mm), k (0.5 mm) and m (10 μm).

Extended Data Fig. 6 Biomineralized fossils of the Castle Bank fauna.

a, undescribed fenestellid bryozoan from uncertain level, attached to poorly preserved orthocone nautiloid (NMW.2021.3 G.62); b, phosphatic tube of the cnidarian Sphenothallus sp., from uncertain level (NMW.2021.3 G.63); c, brachiopod Monobolina ramsayi from level A0 (NMW.2021.3 G.68); d, unidentified acrotretid brachiopod (NMW.2021.3 G.90); e; encrusting brachiopod Schizocrania multistriata from uncertain level (NMW.2021.3 G.91); f, cnidarian Paraconularia sp. (NMW.2021.3 G.92). Scale bars: a–c, e–f: 1 mm; d: 0.5 mm.

Extended Data Fig. 7 Small carbonaceous fossils from levels A3–4 and A11 at Castle Bank.

a–g, portions of brachiopod shell layers probably sourced from Apatobolus micula; a, PMU 39383/1; b, PMU 39372/1 enlarged in (b1), showing pitted surface produced by spongy wall; c, PMU 39349/3 enlarged in c1, showing pitted microstructure; d, PMU 39387/1 enlarged in (d1) and (d2), showing reticulated to anastomosing networks; e, PMU 39391/1 enlarged in (e1), showing reticulated surface structure; f, PMU 39350/2 enlarged in (f1), showing reticulated patterns grading into anastomosing structures; g–k, variably patterned cuticular fragments; g, PMU 39367/1 enlarged in (g1); h, PMU 39354/1 enlarged in (h1); i, PMU 39387/2; j, PMU 39364/1 enlarged in (j1); k, PMU 39334/1 showing parallel network of elongated pores; l, m, tubular microfossils; l, PMU 39338/1; m, PMU 39375/1; n, PMU 39349/1, graptolite fragment possibly sourced from Didymograptus murchisoni; o, PMU 39350/1, striped cuticular fragment possibly sourced from a wiwaxiid sclerite (see Harvey et al.49, fig. 3); p, PMU 39390/1, scolecodont; q, PMU 39349/2, unknown spine possibly sourced from scolecodonts; r–s, acritarchs; r, PMU 39360/1, sphaeromorph with granulose ornamentation enlarged in (r1); s, PMU 39359/1, Filisphaeridium sp. showing sharp solid processes enlarged in (s1); t–v, chitinozoans; t, PMU 39343/1; u, PMU 39351/1; v, PMU 39363/1 enlarged in (v1) and (v2), showing spinose ornamentation; w, PMU 39381/1, Leiosphaeridia sp. Scale bar equals 50 µm except m (100 µm) and enlargements in a2 (25 µm), a1, d1, d2, e1, f1, g1, h1, j1, r1, s1, v1, v2 (17 µm), b1 and c1 (10 µm).

Extended Data Fig. 8 Current estimated diversity of taxonomic groups in the Castle Bank fauna.

Abundance is given schematically on left side, showing the distribution of different abundance levels (abundant to rare) of the species included within that taxonomic unit. Abundant species are those that are found in almost every block; common species are expected to be found several times in a field day; scarce species may be encountered once in every few field days; and rare species have been found only a small number of times. An absolute scale is provided for taxa known from three, two and one specimens. The diversity figures are estimates pending full taxonomic treatment, especially for sponges and arthropods.

Extended Data Fig. 9 Additional taphonomic data.

a–h, undescribed palaeoscolecid worm (NIGP175890). a, overall SEM view of distal end of specimen; b, elemental map of carbon covering same view; c, high-resolution SEM image of detail of cuticle, showing plate morphology and intervening microplate array; d, detail of distal termination of worm, with elemental maps showing distribution of: e, carbon; f, iron; g, silicon; h, aluminium; i–k, valve of phosphatic (obolid) brachiopod Apatobolus micula (NMW.2021.3 G.64ii) showing preservation as carbon film (j) and virtual absence of phosphate (k); l–p, sponge (as in Extended Data Fig. 3b), with detail of texture of sponge at margin, showing framboid impressions (l), overall view in backscattered SEM (m), and with elemental maps of carbon (m), oxygen (n) and iron (o), showing entirely carbonaceous composition (NIGP175889). Scale bars: a, b, d–l: 100 μm; c: 10 μm; m–p: 1 mm.

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Botting, J.P., Muir, L.A., Pates, S. et al. A Middle Ordovician Burgess Shale-type fauna from Castle Bank, Wales (UK). Nat Ecol Evol 7, 666–674 (2023).

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