1. Introduction
The terminal Ediacaran constitutes a pivotal interval in the fossiliferous record, marking the first stratigraphic appearance of macroscopic multicellular soft-bodied organisms, precursors to the biomineralized, actively burrowing Cambrian faunas. This interval is traditionally subdivided into three ecostratigraphic units – known as the Avalon, White Sea and Nama assemblages (Waggoner, Reference Waggoner2003) – each characterized by distinct faunal compositions, palaeogeographic distribution and depositional settings. The oldest Avalon Assemblage is predominantly recorded in deep marine siliciclastic facies, the following White Sea Assemblage in nearshore to offshore shelfal siliciclastic and carbonate, and the youngest Nama Assemblage in similar shelfal facies (Bowyer et al. Reference Bowyer, Wood and Yilales2024). Recent findings, however, suggest that the Avalon and White Sea assemblages overlap temporally, and may instead reflect spatial rather than strictly temporal differences, as predicted by the increasing identification of contemporaneous genera across biotas (Bowyer et al. Reference Bowyer, Wood and Yilales2024, fig. 1).
Typical preservation in Avalon Assemblage deposits involves the casting of soft-bodied impressions beneath volcaniclastic event beds. These Konservat-Lagerstätten are assessed as conforming to the ‘death-mask’ model, whereby early diagenetic reactions between microbial mats, carcasses and sediment induce authigenic mineralization of an iron sulphide veneer (with frequent telodiagenetic alteration to iron oxide) between the carcasses and the smothering sediment, accounting for the fidelity of soft-tissue preservation (Gehling, Reference Gehling1999; Liu, Reference Liu2016; MacGabhann et al. Reference MacGabhann, Schiffbauer, Hagadorn, Van Roy, Lynch, Morrison and Murray2019; McKean et al. Reference Mckean, Taylor and McIlroy2023). In recent years, alternative models have proposed the formation of early diagenetic clays (Becker-Kerber et al. Reference Becker-Kerber, El Albani, Konhauser, Abd Elmola, Fontaine, Paim, Mazurier, Prado, Galante, Kerber, da Rosa, Fairchild, Meunier and Pacheco2021) and the rapid precipitation of silica induced by microbial biofilms (Slagter et al. Reference Slagter, Hao, Planavsky, Konhauser and Tarhan2022) to address Ediacaran-type moldic fossilization. In Newfoundland, Ediacaran macrofossils occur mainly in the Conception and St. John’s groups (Matthews et al. Reference Matthews, Liu, Yang, McIlroy, Levell and Condon2021, fig. 1), which record a progressive increase in generic diversity (Matthews et al. Reference Matthews, Liu, Yang, McIlroy, Levell and Condon2021, fig. 5) yet are dominated in density by the Rangeomorpha and Arboreomorpha.
Arboreomorphs are frondose organisms that form a sister clade to the iconic rangeomorphs (Hoyal Cuthill & Han, Reference Hoyal Cuthill and Han2018), from which they differ primarily in branching architecture. Rangeomorph branching follows a pseudofractal pattern (Brasier & Antcliffe, Reference Brasier and Antcliffe2009; Brasier et al. Reference Brasier, Antcliffe and Liu2012), with multiple (at least three) hierarchical orders of self-similar modules in which lower-order units derive from the repetition of higher-order structures (see McIlroy, Reference McIlroy2025). In contrast, arboreomorphs – depending on the genus – exhibit only second- or third-order branches, with no further recursive subdivision. Their first-order branches are parallel to one another (Erwin et al. Reference Erwin, Laflamme, Tweedt, Sperling, Pisani and Peterson2011). Their second- and third-order branches also typically arise perpendicularly from their parent branch, whereas rangeomorph branches – particularly those of the first-order – more commonly diverge at acute angles (Grimes et al. Reference Grimes, Narbonne, Gehling, Trusler and Dececchi2024). Another common feature of arboreomorphs is the marginal rim, a structure encircling the petalodium, to which first-order branches are attached (Erwin et al. Reference Erwin, Laflamme, Tweedt, Sperling, Pisani and Peterson2011).
Some specimens of Arboreomorpha are among the largest frondose organisms known from this period, reaching lengths of up to two metres (Dunn et al. Reference Dunn, Liu and Gehling2019, fig. S2). Interestingly, they rank among the most abundant fossils in certain Ediacaran biotas (Australia, Ediacara Range – Grimes et al. Reference Grimes, Narbonne, Gehling, Trusler and Dececchi2024), yet exhibit relatively low generic diversity, with only three valid genera being currently recognized: Akrophyllas Grimes et al. Reference Grimes, Narbonne, Gehling, Trusler and Dececchi2024, Arborea Glaessner & Wade, Reference Glaessner and Wade1966 and Charniodiscus Ford, Reference Ford1958.
The genus Arborea was first described by Glaessner & Wade (Reference Glaessner and Wade1966), but it was later synonymized with Charniodiscus by Jenkins & Gehling (Reference Jenkins and Gehling1978). Laflamme et al. (Reference Laflamme, Gehling and Droser2018) subsequently reinstated Arborea as a valid genus, based on a detailed morphological analysis of Australian specimens and – following the recommendations of Brasier & Antcliffe (Reference Brasier and Antcliffe2009) – transferred Charniodiscus arboreus (Glaessner & Daily, Reference Glaessner and Daily1959) together with C. oppositus (Jenkins & Gehling, Reference Jenkins and Gehling1978) to Arborea, designating A. arborea as the type species. Pérez-Pinedo et al. (Reference Pérez-Pinedo, McKean, Taylor, Nicholls and McIlroy2022) later recommended that the species C. longus (Glaessner & Wade, Reference Glaessner and Wade1966), C. oppositus (confirming Laflamme et al. Reference Laflamme, Gehling and Droser2018) and C. spinosus (Laflamme et al. Reference LaFlamme, Narbonne and Anderson2004) be transferred to Arborea (A. longa; A. opposita; A. spinosa). Their proposal was based on a taphonomic study of the holotype of Charniodiscus, which they demonstrated to have a subconical frond rather than the planar frond typical of Arborea. Grimes et al. (Reference Grimes, Narbonne, Gehling, Trusler and Dececchi2024) subsequently erected the genus Akrophyllas, reassigning Arborea longa as its type species (Akrophyllas longa). The genus Arborea is therefore characterized by the planar geometry of the petalodium, the presence of a basal backing sheet (Pérez-Pinedo et al. Reference Pérez-Pinedo, McKean, Taylor, Nicholls and McIlroy2022), and second-order branches that typically exhibit a morphology ranging from globular to comb-shaped (Laflamme et al. Reference Laflamme, Gehling and Droser2018; Dunn et al. Reference Dunn, Liu and Gehling2019; the terms ‘teardrop-shaped’ and ‘peapod unit’ are also used in the literature).
Herein, we describe and figure a new species of Arborea from the late Ediacaran Mistaken Point Formation of Newfoundland, characterized by a slender petalodium, proportionally wide first-order branches, a broad basal disc and a reduced stem.
2. Materials and methods
2.a. Geological setting
The type material was recovered from the southern end of Halfway Cove (Figure 1; see King, Reference King1990) from an outcrop exposed by a rockfall. The site is located near the town of Logy Bay-Middle Cove-Outer Cove, along a coastal strip. The slab bearing the specimens was found in situ and largely intact, albeit loosened, while overhanging, heavily weathered rock debris posed an immediate hazard. Extraction from the field was conducted under special permit P24.07 issued by the province of Newfoundland. The type locality lies approximately 10.45 m above the red marker bed that is part of the ‘5m’ unit of the Middle Cove Member of the lower Mistaken Point Formation, as mapped by King (Reference King1990). The Middle Cove Member in the St. John’s area has not been directly dated; however, its depositional age can be constrained through regional stratigraphic relationships. Recent detrital zircon U–Pb ages from the overlying Hibbs Cove Member in Spaniard’s Bay, near its type locality on the Port de Grave Peninsula (King, Reference King1990), indicate a maximum depositional age of 557 ± 3 Ma (Khatrine & Lowe, Reference Khatrine and Lowe2025). Given that the Hibbs Cove Member has also been documented in the St. John’s region (King, Reference King1990), the underlying strata of the Middle Cove Member bearing A. elegans sp. nov. are estimated to have been deposited between ca. 561 and 557 Ma. The depositional environment is interpreted as a proximal continental slope, indicated by evidence of slumping and interbedded coarse-grained sandstone and pebbly layers within the stratigraphic sequence.
(a) General map of Newfoundland, Atlantic Canada. (b) Detail of the Avalon and Bonavista peninsulas, showing the locations of the studied site (Halfway Cove), Discovery UNESCO Global Geopark, Mistaken Point Ecological Reserve, and the city of St. John’s, for geographic reference. (c) Stratigraphic position of the type material.
2.b. Type material
The holotype is preserved as a positive epirelief for the petalodium, negative epirelief for the basal disc, on a turbiditic fine mudstone containing sparse volcanic-derived grains (angular feldspars), overlain by lithologically similar material. Three additional specimens of the same species, exhibiting the same type of preservation, are present in the sample; two of these were designated as paratypes.
2.c. Preparation, photography and terminology
Two silicone moulds of the holotype and paratypes were made from the slab using Mold Star 20T. Two homogeneously coloured casts were subsequently created from the silicone moulds using jesmonite AC100, mixed with brown pigment, for illustration purposes. The type material and casts were photographed with a Canon EOS 5D Mark IV camera, with an attached EF 24–105mm f/4L IS II USM lens, and with a Fujifilm X-T5 camera, with an attached Fujinon XF 16–50mm f/2.8–4.8 R LM WR lens. Arboreomorph anatomical terminology is adapted from Laflamme et al. (Reference Laflamme, Gehling and Droser2018) and Dunn et al. (Reference Dunn, Liu and Gehling2019).
2.d. Repositories
The type material is housed at The Rooms Provincial Museum, St. John’s, Newfoundland, Canada, with registration numbers NFM F-4034, NFM F-4035 and NFM F-4036.
3. Systematic palaeontology
Phylum †Petalonamae Pflug, Reference Pflug1972
Clade †Arboreomorpha Erwin et al. Reference Erwin, Laflamme, Tweedt, Sperling, Pisani and Peterson2011
Family incertae sedis
Genus †Arborea Glaessner & Wade, Reference Glaessner and Wade1966
Type species †Arborea arborea (Glaessner & Daily, Reference Glaessner and Daily1959)
Other species †Arborea denticulata Wang et al. Reference Wang, Pang, Chen, Wan, Xiao, Zhou and Yuan2020; †Arborea opposita (Jenkins & Gehling, Reference Jenkins and Gehling1978); †Arborea spinosa (Laflamme et al. Reference LaFlamme, Narbonne and Anderson2004)
†Arborea elegans sp. nov.
Arborea elegans sp. nov., holotype, NFM F-4034. (a) General view. (b) Basal disc and proximal end of the petalodium. (c) Distal end of the petalodium. (d) Line drawing. Scale bar is 5 cm in (a) and (d), and 1 cm in (b) and (c).
Arborea elegans sp. nov., paratypes, NFM F-4035, NFM F-4036, overlapping. (a) Top-lit. (b) Side-lit, to enhance structural details. NFM F-4035 is highlighted in blue, NFM F-4036 in purple. The white arrow marks an adjacent specimen tentatively attributed to Charnia. All scale bars are 5 cm.
LSID. https://zoobank.org/NomenclaturalActs/655BEE8C-9270-40B6-B5C6-995CF6E35A3F.
Etymology. The specific epithet is derived from the Latin adjective elegans, meaning ‘graceful’ or ‘refined’, and was chosen to underscore the slender, elegant morphology of the species. It is treated as an adjective in the nominative singular case, in agreement with the feminine genus name Arborea.
Holotype. NFM F-4034, positive (basal disc negative) epirelief on a mudstone/siltstone slab measuring 55 × 19 × 10 cm, with 3 additional specimens of the same species co-occurring on the slab. Deposited in the collection of The Rooms Provincial Museum, St. John’s, Newfoundland, Canada.
Referred material. NFM F-4035, NFM F-4036, positive (basal disc negative) epireliefs, co-occurring on the same mudstone/siltstone slab as the holotype.
Locality and horizon. Lower Mistaken Point Formation (Middle Cove Member), near the town of Logy Bay-Middle Cove-Outer Cove, Newfoundland, Canada; Ediacaran.
Diagnosis. Slender, planar petalodium, tapering proximodistally along most of the axis, with slight narrowing at basal disc attachment. Basal disc present, markedly wider than the petalodium. Stem reduced, either absent or with a length not exceeding the radius of the basal disc. Stalk prominent, exposed along the whole length of the petalodium, widening in the proximal-most third. First-order branches rectangular, opposite, arising orthogonally from the stalk, approximately twice as long as wide. The distal end of the first-order branches is curved at 90° towards the distal end of the petalodium, merging with adjacent branch apices to form a marginal rim.
Description. Based on holotype NFM F-4034 (Figure 2). Body length 10.23 cm (from the centre of the basal disc to the tip of the petalodium), width 1.5 cm (widest area of the petalodium).
The basal disc is 2.67 cm long, 2.15 cm wide, 1/3 wider than the proximal end of the petalodium. It is composed of three concentric rings. The central ring encompasses a circular depression.
The stem cannot be observed due to the preservation; if present, it is shorter than the radius of the basal disc.
The petalodium is elongate and lanceolate; its sides taper gently along the entire proximodistal axis, except for a slight narrowing near the basal disc attachment. The backing (dorsal sensu Laflamme et al. Reference Laflamme, Gehling and Droser2018) sheet is inconspicuous, either due to its absence or taphonomy. The central axis of the petalodium (stalk) is prominent and exposed along its whole length, and especially undulate near its distal end. The stalk is seemingly wider in the proximal-most third of the frond. The petalodium – particularly its stalk and branches – is better preserved beyond its most proximal third.
Two rows of approximately opposite (a few branches seem slightly alternate, as is seen in Arborea denticulata), rectangular first-order branches arise orthogonally from a stalk forming the central axis (i.e. central axis exposed and linear). The branching angle of the three most proximal pairs ranges proximodistally from 80° to 90°. The length of the first-order branches is approximately twice their width. Around 35 first-order branches per row. A sharp marginal rim is formed by the curvature and merging of the distal ends of adjacent first-order branches, delineating the lateral outline of the petalodium. The angle of the distally oriented bend is approximately 90°. The margin appears to be discontinuous in localized areas, mainly towards the distal end of the petalodium, where the stalk is curved.
Remarks. The paratypes NFM F-4035 and NFM F-4036 (Figure 3) were entombed in close association, with NFM F-4036 overlapping NFM F-4035. A third specimen of the same species, co-occurring on the slab, is not figured herein due to its poor preservation. An additional specimen, attributed to Charnia Ford, Reference Ford1958, is figured alongside the paratypes (Figure 3b).
4. Discussion
4.a. Systematic placement
The new specimens of Arborea elegans sp. nov. are readily attributed to the clade Arboreomorpha because of the following characters: bifoliate petaloids consisting of parallel primary branches which diverge from the central stalk at acute to right angles (45°–90°) and end at an outer margin; the branches are all joined together (Erwin et al. Reference Erwin, Laflamme, Tweedt, Sperling, Pisani and Peterson2011, supplementary material). The prominent central stalk of A. elegans, also diagnostic of the Arboreomorpha, widens in the proximal-most third of the petalodium, similar to the pattern observed in Arborea arborea (Dunn et al. Reference Dunn, Liu and Gehling2019). It should be noted that arboreomorphs can present a front–back asymmetry, and that the displayed faces of the described specimens remain indeterminate. Given that all four specimens on the slab exhibit the same morphology, the presence of a distinct asymmetry in this species is considered unlikely, though not impossible. This consistency suggests that either all individuals display the same face or that taphonomy and/or erosion have rendered both faces morphologically similar.
The new specimens can be excluded from the genus Charniodiscus based on the following characters, provided in the emended diagnosis of the genus by Pérez-Pinedo et al. (Reference Pérez-Pinedo, McKean, Taylor, Nicholls and McIlroy2022): unipolar frondose arboreomorphs with stem (stem very short or absent in A. elegans, whereas both valid species of Charniodiscus – C. concentricus Ford, Reference Ford1958 and C. procerus Laflamme et al. Reference LaFlamme, Narbonne and Anderson2004; see Pérez-Pinedo et al. Reference Pérez-Pinedo, McKean, Taylor, Nicholls and McIlroy2022 – have distinct stems, constituting between a quarter to one half of the total frond length); outer surface of the branches has transverse ridges orthogonal to the long axis of the branches; the internal surface of the branch has similar oblique ridges close to the junction with the stem (both inconspicuous in A. elegans); the branches are distally curved forming a subconical frond in life (no evidence of such a subconical frond structure in A. elegans; more specifically, the first-order branches are straight for most of their length, then distally abruptly curved at approx. 90° and joined in a marginal rim, as opposed to Charniodiscus, in which the branches are – when outfolded – curved/arcuate over a greater length and at a shallower angle, not joined by their tips folded into a marginal rim, but laterally by a series of orthogonal to oblique transverse ridges).
Comparison with the emended generic diagnosis of Arborea by Laflamme et al. (Reference Laflamme, Gehling and Droser2018) reveals two differing characters: frond with ovate bifoliate petalodium (lanceolate in A. elegans); petalodium tapers distally (tapering along nearly the entire length of the petalodium in A. elegans). The backing (or dorsal) sheet, a key feature of the genus typically marked by a wrinkled or striated texture between branches (Laflamme et al. Reference Laflamme, Gehling and Droser2018; Dunn et al. Reference Dunn, Liu and Gehling2019; Pérez-Pinedo et al. Reference Pérez-Pinedo, McKean, Taylor, Nicholls and McIlroy2022), is absent or not preserved here – a condition also observed in several other congeneric specimens from the type locality (Laflamme et al. Reference Laflamme, Gehling and Droser2018; Dunn et al. Reference Dunn, Liu and Gehling2019), likely resulting from taphonomic loss.
The only species within the Arboreomorpha resembling the specimens of Arborea elegans in shape is Akrophyllas longa, bearing a similar elongate, gently tapering petalodium. The absence of high-order branching in the described specimens of A. elegans precludes constructive comparison of related characters with Akrophyllas longa. A significant difference between the two taxa is that in Akrophyllas longa, first-order branches arise from the stalk at an acute angle, whereas in A. elegans, they emerge orthogonally. First-order branch proportions are also different, being more slender in Akrophyllas longa (approx. 2:1 length:width ratio in A. elegans, 4:1 in Akrophyllas longa). The basal disc is also proportionally larger in A. elegans, being 1/3 wider than the proximal end of the petalodium (approx. same width in Akrophyllas longa). Perhaps the most diagnostic feature of Akrophyllas longa is its front–back asymmetry, characterized by a prominent stalk on one side and a concealed stalk on the other. On the concealed side, the presence of alternate first-order branches creates a zigzagging central axis, reminiscent of the rangeomorph Charnia. Neither of these characters is observed in A. elegans, but this may result from all known specimens preserving the same face (presumably the front – ‘obverse’ sensu Grimes et al. Reference Grimes, Narbonne, Gehling, Trusler and Dececchi2024). However, this would be contrasting with the description of Grimes et al. (Reference Grimes, Narbonne, Gehling, Trusler and Dececchi2024), explaining that those two variants are usually equally abundant in the studied bedding planes. The slab preserving the type material of A. elegans does contain an additional fossil with first-order branching typical of Charnia (Figure 3b), but, given its acute branching angle (approx. 45°) compared to the orthogonal branching of the type material of A. elegans, it is considered unlikely to be conspecific with A. elegans and is instead tentatively assigned to Charnia. Another difference from Akrophyllas longa that supports this interpretation is the arrangement of first-order branches on both sides of the petalodium: alternate in Akrophyllas longa, but mostly opposite in A. elegans (a few pairs appear slightly alternate). To be consistent with the branching anatomy of Akrophyllas longa, exhibiting Charnia-like alternate first-order branching on one side, alternating branches would also be expected on the opposite side.
Although the genus Paracharnia Sun, Reference Sun1986 was classified within Rangeomorpha Pflug, Reference Pflug1972 by Sepkoski (Reference Sepkoski2002), the accompanying illustration exhibits arboreomorph-type branching (two orders of branches, with the second arising orthogonally from the first), although this cannot be confirmed from the photograph. However, the affinity of the newly described specimens with Paracharnia can be ruled out because the unlinked (free-standing sensu Sun, Reference Sun1986) nature of the first-order branches (linked in A. elegans). Another distinctive character is the markedly wide stalk of Paracharnia, which is considerably broader than that of A. elegans. The basal disc figured in Sun (Reference Sun1986) is also proportionally smaller than in A. elegans; however, since the holotype of Paracharnia dengyingensis (Ding & Chen, Reference Ding and Chen1981) is twice as long as the type material of A. elegans, the difference could be attributed to allometric growth if they were conspecific.
Another broadly comparable genus is the monotypic rangeomorph Frondophyllas Bamforth & Narbonne, Reference Bamforth and Narbonne2009, but it is ruled out because of the two following diagnostic characters: leaflet-bearing branches emerging in slightly offset pairs at regular intervals along wide, continuous central rod (no evidence of leaflet-analogous structures in A. elegans); branching angle inconsistent along central rod, varying between 50° and 80° (consistent at approx. 90° in A. elegans). Moreover, the first-order branches of Frondophyllas are widely spaced along its central rod, contrasting with the tightly packed branches of A. elegans. There is also no evidence of a marginal rim in Frondophyllas, owing to the unlinked nature of its first-order branches (linked in A. elegans). However, no specimens of Frondophyllas similar in size to A. elegans have been described to date.
Based on these observations, the newly described specimens appear to be most closely related to the genus Arborea, differing only by a slight variation in the shape of the petalodium. In contrast, although the genus Akrophyllas exhibits a similar petalodium shape, its first-order branching architecture is different, and it shows pronounced asymmetry between its anterior and posterior surfaces – a distinctive feature not seen in A. elegans. Consequently, based on a parsimonious interpretation of these traits, the new species is readily assigned to the genus Arborea.
Comparison with other species of Arborea reveals significant differences, preventing the attribution of the specimens to any existing species.
The basal disc is proportionally larger than in A. arborea, the petalodium is more slender, and the first-order branches are wider (approx. 2:1 length:width ratio in A. elegans, 3.6:1 in A. arborea). The shape of the petalodium is elongate lanceolate in A. elegans, but is ovate in A. arborea.
The most conspicuous difference with A. denticulata is the presence of a stem comprising approximately 20% of the total length of the petalodium, which is absent or very short in A. elegans. The petalodium is elliptical in A. denticulata, but elongate lanceolate in A. elegans. The first-order branches are similar in shape in both species, but are alternate in A. denticulata and typically opposite in A. elegans.
In turn, A. opposita differs from A. elegans by having thinner first-order branches (approx. 3.5:1 length:width ratio in A. opposita, 2:1 in A. elegans), diverging from the stalk at more acute angles (65°–85° in A. opposita, approx. 90° in A. elegans).
The last valid species of the genus, A. spinosa, has an ovate petalodium, a prominent apical spine, and a short, broad stem – features absent in A. elegans.
4.b. Retrodeformation
No evidence of significant deformation is observed in two dimensions along the bedding plane. Basal discs, commonly used as deformation proxies in Ediacaran palaeontology (Wood et al. Reference Wood, Dalrymple, Narbonne, Gehling and Clapham2003), are nearly circular in the described specimens, and the slab lacks pronounced cleavage or shear motions on the bedding plane. In the absence of any additional reliable indicators of distortion, no correction was considered justified.
4.c. Palaeobiology: taphonomy, inferred life position
Considering the stratigraphic context, the fossils are interpreted as epireliefs (preserved on the upper surface of the sedimentary bed). The basal disc, a negative epirelief, is regarded as an imprint, based on the presence of a central depression and the absence of an overlying stem, consistent with examples illustrated by Gehling (Reference Gehling1999, fig. 11) and MacGabhann et al. (Reference MacGabhann, Schiffbauer, Hagadorn, Van Roy, Lynch, Morrison and Murray2019, fig. 10). In contrast, the frond, a positive epirelief, is interpreted as a counterimprint (i.e. the original shape of the organism) for both the stalk and the first-order branches, owing to their raised topography. In some taxa (e.g. Fractofusus Gehling & Narbonne, Reference Gehling and Narbonne2007), an imprint may be expressed as partial positive epirelief, but this does not apply here: if the frond represented an imprint, the stalk would appear as a pronounced furrow widening toward the basal disc on the counterimprint. This morphology would be inconsistent with the anatomy of Arborea specimens preserved as positive hyporeliefs, which provide an appropriate analogue for the hypothetical counterimprint. Such Arborea specimens (see pictures and reconstructions in Dunn et al. Reference Dunn, Liu and Gehling2019) indeed exhibit a prominent stalk on both surfaces, rather than a furrow. Laflamme et al. (Reference Laflamme, Gehling and Droser2018) likewise note that the stalk of Arborea is typically preserved in positive relief, further supporting this interpretation. As stated in the species description, the petalodium of A. elegans sp. nov. – particularly its stalk and branches – becomes more prominent and detailed beyond its most proximal third. This preservation pattern is typical of arboreomorphs with an upright or recumbent mode of life (Figure 4), in which the arched, protruding stem (or proximal stalk here) is more poorly preserved than the rest of the fallen frond, which lies more firmly appressed to the sediment and is more readily entombed (Pérez-Pinedo et al. Reference Pérez-Pinedo, McKean, Taylor, Nicholls and McIlroy2022, fig. 4).
Three-dimensional interpretative reconstruction of Arborea elegans within its habitat.
5. Conclusions
The discovery and systematic description of Arborea elegans sp. nov. expands the known diversity of one of the few polyspecific Ediacaran genera, and represents the first new species identified from the Conception Group of the northeastern Avalon Peninsula since the mapping of King (Reference King1990). Recovery of additional, better-preserved specimens of A. elegans would be valuable for assessing the presence of genus-typical features – such as second-order branches and the backing sheet – not preserved in the type material. Continued exploration and detailed description of the area, as part of ongoing work, will be crucial for advancing our understanding of the local palaeobiota and refining interpretations of the depositional environment.
Acknowledgements
Ediacaran fossils in Newfoundland are legally protected and may only be collected and studied under permit, with all specimens accessioned into the collections of The Rooms Provincial Museum. The authors thank Dr Jamie Brake for issuing the permit enabling the collection of the loose slab bearing the type material on short notice, as it was at immediate risk. We also extend our thanks to Natural History Collections Manager Nathalie Djan-Chékar for accessioning the specimen into The Rooms collections; to Heléna Muirhead-Hunt for her comments on the manuscript’s language and clarity; to the anonymous reviewer for their constructive feedback; and to Dr Van de Schootbrugge for his editorial support. This research was supported by an NSERC Discovery Grant (#RGPIN 2025-0568) awarded to Duncan McIlroy and forms part of the PhD projects of Simon Rosse-Guillevic and Pascal Olschewski.
Competing interests
The authors declare none.
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