taxonID	type	description	language	source
03FD8143EC07FFACFCBCFF07FCEC9CF0.taxon	description	Figures 1 – 5, Supplementary Figs. 2 – 4	en	Pates, Stephen, Botting, Joseph P., Muir, Lucy A., Wolfe, Joanna M. (2022): Ordovician opabiniid-like animals and the role of the proboscis in euarthropod head evolution. Nature Communications 13 (1): 1-15, DOI: 10.1038/s41467-022-34204-w, URL: http://dx.doi.org/10.1038/s41467-022-34204-w
03FD8143EC07FFACFCBCFF07FCEC9CF0.taxon	etymology	Etymology. After Bonnie Douel, niece of the site owners and fossil devotee; the family has followed and supported the research extensively since the discovery of the fauna.	en	Pates, Stephen, Botting, Joseph P., Muir, Lucy A., Wolfe, Joanna M. (2022): Ordovician opabiniid-like animals and the role of the proboscis in euarthropod head evolution. Nature Communications 13 (1): 1-15, DOI: 10.1038/s41467-022-34204-w, URL: http://dx.doi.org/10.1038/s41467-022-34204-w
03FD8143EC07FFACFCBCFF07FCEC9CF0.taxon	materials_examined	Holotype. NMW. 2021.3 G. 7 known from part and counterpart. Counterpart preserves anterior portion only. Locality and horizon. Collected from the Darriwilian (Middle Ordovician, Didymograptusmurchisoni Biozone) Gilwern Volcanic Formation at Castle Bank, near Llandrindod, Powys (UK) 33, 34.	en	Pates, Stephen, Botting, Joseph P., Muir, Lucy A., Wolfe, Joanna M. (2022): Ordovician opabiniid-like animals and the role of the proboscis in euarthropod head evolution. Nature Communications 13 (1): 1-15, DOI: 10.1038/s41467-022-34204-w, URL: http://dx.doi.org/10.1038/s41467-022-34204-w
03FD8143EC07FFACFCBCFF07FCEC9CF0.taxon	diagnosis	Diagnosis. As for genus, by monotypy.	en	Pates, Stephen, Botting, Joseph P., Muir, Lucy A., Wolfe, Joanna M. (2022): Ordovician opabiniid-like animals and the role of the proboscis in euarthropod head evolution. Nature Communications 13 (1): 1-15, DOI: 10.1038/s41467-022-34204-w, URL: http://dx.doi.org/10.1038/s41467-022-34204-w
03FD8143EC07FFACFCBCFF07FCEC9CF0.taxon	description	Description. NMW. 2021.3 G. 7 preserves the head region and anterior portion of the trunk (Fig. 1). The specimen, which measures ~ 13 mm along the dorsal margin (not including proboscis), is twisted so that the anterior provides an oblique-lateral view, which becomes more oblique-ventral towards the posterior. The head region preserves evidence for a dorsal sclerite, annulated proboscis, and posterior-facing mouth composed of sclerotized plates. The dorsal sclerite (length ~ 2 mm) has a rounded lateral margin. The proboscis, which is a single structure and not an overlapping pair of appendages, measures ca. 3 mm along its dorsal margin, is annulated, curves ventrally, and displays slender spines at regular intervals (~ 0.2 mm spacing, one per two to four annulations) along its dorsal margin (Figs. 2 a, 3, 4 d, Supplementary Fig. 2). Evidence for a posteriorfacing mouth is provided by the gut trace, which twists ventrally where it connects to the mouth (Figs. 2 a, 4 c, Supplementary Fig. 3). The mouth is ~ 0.4 mm in diameter and preserves evidence for small, lightly sclerotized plates subequal in size (Supplementary Fig. 4). Plate boundaries are most visible at the anterior and posterior of the ring; the left and right sides display greater disarticulation and are less complete (Supplementary Fig. 4). The trunk bears two sets of appendages: dorsolateral flaps and ventral lobopodous limbs. Flaps intersect with faint curved boundaries, interpreted as the body margin, and display a subrectangular outline with rounded margins (Fig. 5 b). Flaps decrease in size towards the posterior (lf 1 measures ~ 3 mm along its long axis, lf 3 ~ 2 mm). Although most flaps display a smooth external surface, the anteriormost flaps provide evidence for internal linear features, interpreted as strengthening rays (Figs. 2 b, c, 4 c). These are visible in the left anterior flap, which has been split obliquely, revealing interior structures. The strengthening rays run parallel to the long axis of the flap and cover most of the flap width. Both anterior flaps display a darker region that covers most of the surface facing the body midline. This darker region preserves fine lines that run perpendicular to the strengthening rays, interpreted as setal structures. Additional setal structures protrude from underneath the posterior margins of other flaps (e. g. Fig. 5 b). Towards the posterior, the body is twisted and the swimming flaps become preserved more obliquely. This reveals a second ventral series of lobopodous limbs (Fig. 5 c, d). These limbs are triangular in outline and display lineations that run perpendicular to the long axis, interpreted as annuli. Spines protrude from the posterior margin (Fig. 5 c, d).	en	Pates, Stephen, Botting, Joseph P., Muir, Lucy A., Wolfe, Joanna M. (2022): Ordovician opabiniid-like animals and the role of the proboscis in euarthropod head evolution. Nature Communications 13 (1): 1-15, DOI: 10.1038/s41467-022-34204-w, URL: http://dx.doi.org/10.1038/s41467-022-34204-w
03FD8143EC07FFACFCBCFF07FCEC9CF0.taxon	discussion	Remarks. The unique combination of characters, including some previously considered exclusive to opabiniids (annulated proboscis) and radiodonts (dorsal spines on the protocerebral appendage) supports the erection of a new genus and species. Phylogenetic analyses support Mieridduryn bonniae nov. gen. et sp. as the most stemwardmember of the euarthropodstem lineage thatbears dorsal spines on the protocerebral appendage and dorsolateral flaps with strengthening rays, and most crownward member to exhibit lobopodous ventral limbs (further remarks in Supplementary Information).	en	Pates, Stephen, Botting, Joseph P., Muir, Lucy A., Wolfe, Joanna M. (2022): Ordovician opabiniid-like animals and the role of the proboscis in euarthropod head evolution. Nature Communications 13 (1): 1-15, DOI: 10.1038/s41467-022-34204-w, URL: http://dx.doi.org/10.1038/s41467-022-34204-w
03FD8143EC07FFAFFF75F957FC9499EB.taxon	etymology	Etymology. From Welsh mieri (bramble) and duryn (proboscis, snout), meaning “ bramble-snout ”. The dd is pronounced as a soft th, and results from mutation following a feminine noun. Gender f.	en	Pates, Stephen, Botting, Joseph P., Muir, Lucy A., Wolfe, Joanna M. (2022): Ordovician opabiniid-like animals and the role of the proboscis in euarthropod head evolution. Nature Communications 13 (1): 1-15, DOI: 10.1038/s41467-022-34204-w, URL: http://dx.doi.org/10.1038/s41467-022-34204-w
03FD8143EC07FFAFFF75F957FC9499EB.taxon	diagnosis	Diagnosis. Panarthropod with head region bearing dorsal sclerite, annulated proboscis with spiniform dorsal projections and radial mouthparts composed of small, sclerotized plates; gut trace leading to posterior-facing mouth; trunk bears large subrectangular dorsolateral flaps with rounded distal margins; dorsolateral flaps bear setal structures on surface facing body midline; annulated lobopods display triangular outline and possess short triangular spines on posterior margin.	en	Pates, Stephen, Botting, Joseph P., Muir, Lucy A., Wolfe, Joanna M. (2022): Ordovician opabiniid-like animals and the role of the proboscis in euarthropod head evolution. Nature Communications 13 (1): 1-15, DOI: 10.1038/s41467-022-34204-w, URL: http://dx.doi.org/10.1038/s41467-022-34204-w
03FD8143EC04FFAAFF75FA0BFF0F9E2A.taxon	description	Figures 6 – 9, Supplementary Fig. 5	en	Pates, Stephen, Botting, Joseph P., Muir, Lucy A., Wolfe, Joanna M. (2022): Ordovician opabiniid-like animals and the role of the proboscis in euarthropod head evolution. Nature Communications 13 (1): 1-15, DOI: 10.1038/s41467-022-34204-w, URL: http://dx.doi.org/10.1038/s41467-022-34204-w
03FD8143EC04FFAAFF75FA0BFF0F9E2A.taxon	materials_examined	Material, locality, and horizon. NMW. 2021.3 G. 8, known from part and counterpart. Collected from the Darriwilian (Middle Ordovician, Didymograptus murchisoni Biozone) Gilwern Volcanic Formation at Castle Bank, near Llandrindod, Powys (UK) 33, 34.	en	Pates, Stephen, Botting, Joseph P., Muir, Lucy A., Wolfe, Joanna M. (2022): Ordovician opabiniid-like animals and the role of the proboscis in euarthropod head evolution. Nature Communications 13 (1): 1-15, DOI: 10.1038/s41467-022-34204-w, URL: http://dx.doi.org/10.1038/s41467-022-34204-w
03FD8143EC04FFAAFF75FA0BFF0F9E2A.taxon	description	Description. NMW. 2021.3 G. 8 is a complete specimen preserved compressed to givea lateral viewand measures ~ 3 mm alongthe dorsal margin (Fig. 6). The head region preserves evidence for what appear to be two lateral cephalic sclerites proximal to an annulated proboscis (Figs. 6, 7). A pair of trapezoidal sclerites <1 mm in length, which are compressed and superimposed on each other, have been rotated forwards to cover the anterior of the head and proximal part of the proboscis (Supplementary Fig. 5). The preserved portion of the proboscis is less than 1 mm in length. The cephalic sclerites preserve a marginal rim, and the element covering the right side of the head also displays numerous triangular spines on the anterior and ventral margins (Fig. 7 a, Supplementary Fig. 5). The proboscis, which curves ventrally and is likely incomplete distally, displays annulations and a dark linear feature that runs parallel to the long axis, interpreted as an internal canal, as well as regularly spaced (approximately one per three to four annulations) stout triangular dorsal spines (Figs. 7, 8 c). The proboscis is more similar in preservation to the trapezoidal sclerites than to the trunk. The trunk, which measures ca. 2 mm along the dorsal margin, is curved, narrow and tapers slightly to the posterior. The trunk displays a wrinkled texture. At the anterior (just behind the lateral carapace elements), faint subrectangular elements sit dorsal to the body region (Fig. 7 a; Supplementary Fig. 5). Further to the posterior, indents in the dorsal margin and faint transverse lineations indicate the position of intersegmental furrows and associated subrectangular lateral swimming flaps (Figs. 6, 9). Fainter lines overlain by wrinkles preserved towards the middle of the trunk are also tentatively identified as dorsal furrows and lateral flaps, and indicate the presence of at least 12 furrows and flaps (Fig. 6). The body terminates in a caudalfan ~ 0.25 mm long, composed of triangular caudal blades with spinose lateral and posterior margins. Three blades that widen to the posterior can be observed on the near (right) side, whereas two are observed on the left side (Figs. 8 b, 9).	en	Pates, Stephen, Botting, Joseph P., Muir, Lucy A., Wolfe, Joanna M. (2022): Ordovician opabiniid-like animals and the role of the proboscis in euarthropod head evolution. Nature Communications 13 (1): 1-15, DOI: 10.1038/s41467-022-34204-w, URL: http://dx.doi.org/10.1038/s41467-022-34204-w
03FD8143EC04FFAAFF75FA0BFF0F9E2A.taxon	discussion	Remarks. The wrinkled texture of the body, change in slope on the dorsal margin and orientation of the paired head sclerites (rotated forwards), as well as the lack of internal structures (e. g. guts, nervous system) suggest that this specimen may represent a moult rather than a carcass 39, though this is not conclusive. The presence of an internal cavity does not refute this, as similar structures have been reported from isolated radiodont appendages (e. g. ref. 15 Fig. 13). If this specimen does represent a moult, then it is possible that it bore only a single cephalic sclerite. The appearance of a paired sclerite may have been caused by folding, shearing and breakage of a single, larger, sclerite during the moulting process. The smaller ‘ rectangular elements ’ posterior to this apparently paired sclerite may represent additional broken fragments. If the presence of multiple head sclerites in NMW. 2021.3 G. 8 (rather than one in NMW. 2021.3 G. 7) is confirmed, then this difference and the distinct morphology of the dorsal spines on the proboscis together suggest that NMW. 2021.3 G. 7 may represent a distinct species. Other potentially diagnostic features of NMW. 2021.3 G. 8, such as the spinose caudal fan, are not preserved in NMW. 2021.3 G. 7, but are present in opabiniids Opabinia and Utaurora 36. Alternatively, NMW. 2021.3 G. 8 could alsobe regarded asan earlier ontogenetic stage of Mieridduryn bonniae than NMW. 2021.3 G. 7. At ~ 3 mm, euarthropod A falls within the size range of some larger crustacean larvae (e. g. decapods, remipedes) 40; thus, postembryonic morphological changes such as differing spine form on the proboscis and numberofheadsclerites couldexplain the observeddifferences in the two specimens. Within radiodonts the number of head sclerites is stable at the family level, and does not change during ontogeny (in at least one species, Lyrarapax unguispinus 41), but the number of carapace elements does change during ontogeny in other euarthropods. For example, in the fossil phosphatocopine Dabashanella and the living ostracod Manawa, a univalved carapace develops into a bivalved one 42, 43. Metamorphosis is expected to be ancestral for panarthropods 44 and has been observed in some members of the upper stem group (e. g. the megacheiran Leanchoilia 45, but not all, see ref. 46); hence a comparatively minor morphological change during ontogeny for NMW. 2021.3 G. 7 and NMW. 2021.3 G. 8 cannot be ruled out with the current data. Thus, we leave the smaller specimen in open nomenclature, and consider both possibilities (a distinct species or an earlier ontogenetic stage of Mieridduryn nov. gen.) for this specimen in our phylogenetic analyses (section below). Further discussion of the relationship of Mieridduryn nov. gen. and euarthropod A to opabiniids is provided in Supplementary Information.	en	Pates, Stephen, Botting, Joseph P., Muir, Lucy A., Wolfe, Joanna M. (2022): Ordovician opabiniid-like animals and the role of the proboscis in euarthropod head evolution. Nature Communications 13 (1): 1-15, DOI: 10.1038/s41467-022-34204-w, URL: http://dx.doi.org/10.1038/s41467-022-34204-w
