taxonID	type	description	language	source
03FD87F964530D058B2CF8BEFE7C3995.taxon	materials_examined	Type species: Eiffelia globosa Walcott, 1920; Burgess Shale (Middle Cambrian), British Columbia, Canada.	en	Clausen, Sébastien, Álvaro, J. Javier (2006): Skeletonized microfossils from the Lower-Middle Cambrian transition of the Cantabrian Mountains, northern Spain. Acta Palaeontologica Polonica 51 (2): 223-238, DOI: 10.5281/zenodo.13643839
03FD87F964520D048866FC89FC403B61.taxon	description	Fig. 3 H, I. Material. — Ten specimens preserved as phosphatized steinkerns in the Middle Cambrian “ Beleño ” facies, section Cr 4. Description. — Two−rayed sclerites (up to 500 µm long, distal part of the rays most probably eroded off) diverging at about a right angle with distinct boundary between the rays. Remarks. — These specimens are not interpreted as fragments of three− or four−rayed forms because the two rays diverge at a right angle, are straight and lie on the same plane. Although A. pentactina (Sdzuy, 1969) has a small percentage of 2 + 0 sclerites, the present sclerites seem to represent Allonnia? cf. simplex (Jiang in Luo et al. 1982). However, the foramina are indiscernible because of inadequate preservation of the phosphatic steinkerns	en	Clausen, Sébastien, Álvaro, J. Javier (2006): Skeletonized microfossils from the Lower-Middle Cambrian transition of the Cantabrian Mountains, northern Spain. Acta Palaeontologica Polonica 51 (2): 223-238, DOI: 10.5281/zenodo.13643839
03FD87F964520D048866FDB2FC573D5E.taxon	materials_examined	Type species: Allonnia tripodophora Doré and Reid, 1965; Lower Cambrian, Carteret, Armorican Massif, France. Remarks. — Qian and Bengtson (1989: 19) broadened the concept of the genus [originally including only sclerites with a (3 + 0) formula] to include sclerites with (2 + 0) and (4 + 0) formulas with the rays bending sharply away from the plane of the basal facet.	en	Clausen, Sébastien, Álvaro, J. Javier (2006): Skeletonized microfossils from the Lower-Middle Cambrian transition of the Cantabrian Mountains, northern Spain. Acta Palaeontologica Polonica 51 (2): 223-238, DOI: 10.5281/zenodo.13643839
03FD87F964520D048B2CFB05FC753C24.taxon	discussion	Remarks. — The nomenclature and taxonomy adopted below follow Qian and Bengtson (1989) and Bengtson (in Bengtson et al. 1990) who revised and updated the chancelloriid genera. Chancelloriid (4 + 0) sclerites Fig. 3 E – G. Material. — About 20 specimens preserved as phosphatic steinkerns from the “ Beleño ” facies, sections Cr 1 to Cr 4. Description. — Sclerites having four rays (up to 300 µm long, most distal parts eroded off) merging with distinct external boundaries; some sclerites show rays with varying degrees of curvature (Fig. 3 F), others (Fig. 3 G) have subrectangular outlines of the foramina−bearing base. Remarks. — (4 + 0) sclerites could be assignated to Allonia (A.? tetrathallis sensu Qian and Bengtson, 1989), Chancelloria (C. eros Walcott, 1920), and Archiasterella (A. cf. hirundo sensu Bengtson, in Bengtson et al. 1990; A. pentactina Sdzuy, 1969). Therefore, and because of the differences in ray curvature observed and the general preservation of the sclerites, the use of open nomenclature seems more appropriate here.	en	Clausen, Sébastien, Álvaro, J. Javier (2006): Skeletonized microfossils from the Lower-Middle Cambrian transition of the Cantabrian Mountains, northern Spain. Acta Palaeontologica Polonica 51 (2): 223-238, DOI: 10.5281/zenodo.13643839
03FD87F964520D048B2CFE90FF493A57.taxon	description	Fig. 3 B – D. Material. — More than 100 specimens preserved as secondary phosphatized spicules or phoshatic steinkerns in the Middle Cambrian “ Beleño ” facies, sections Cr 1 to Cr 4. Description. — Siliceous hexactine spicules, exhibiting regular triaxons with six rays at right angles displaying the original spicule symmetry of hexactinellids; size variable, from about 0.2 to 0.8 mm in diameter; rays long and inflated with rounded ends; basal diameter of the ray 80 – 100 µm; in some specimens, the rays radiate from an inflated spherical center reaching 350 – 400 µm in diameter (Fig. 3 D). Normally, the rays are of approximately equal length, but in some specimens a few rays are reduced (probably because of erosion) and, in others, one or two rays reach almost double length. When broken, most of the rays show central canals, and hollow spherical center (Fig. 3 D). Remarks. — Similar inflated hexactines (with inflated rays) have been reported from the Middle Cambrian of Australia (Mehl 1998), and the Upper Cambrian of Argentina (Heredia et al. 1987).	en	Clausen, Sébastien, Álvaro, J. Javier (2006): Skeletonized microfossils from the Lower-Middle Cambrian transition of the Cantabrian Mountains, northern Spain. Acta Palaeontologica Polonica 51 (2): 223-238, DOI: 10.5281/zenodo.13643839
03FD87F964540D028B2CFCD9FD253D70.taxon	materials_examined	Type species: Archiasterella pentactina Sdzuy, 1969; Lower Cambrian (Atdabanian), Cazalla de la Sierra, Ossa Morena, Spain.	en	Clausen, Sébastien, Álvaro, J. Javier (2006): Skeletonized microfossils from the Lower-Middle Cambrian transition of the Cantabrian Mountains, northern Spain. Acta Palaeontologica Polonica 51 (2): 223-238, DOI: 10.5281/zenodo.13643839
03FD87F964540D028B2CF9C5FB473A27.taxon	description	Figs. 3 M, N, 4 A, B. Material. — About 20 specimens from the Middle Cambrian “ Beleño ” facies, section Cr 4. Description. — Sclerites with a tapering central vertical ray (0.5 to 0.7 mm in length) and five to seven prominent, recurved, radiating lateral rays; lateral rays are asymmetrically arranged and commonly differ in size; the curvature of rays is greatest at the intersection with the central ray; they are relatively straight, and make an acute angle (less than 30 °) with the central ray; diameter of the sclerite can reach 0.6 mm, whereas the maximum diameter of the central ray is 0.4 mm; specimens commonly have five to six lateral rays, although a few have seven; they are oval to subrectangular in cross−section, except for the tips, which are round in outline, whereas the whole central ray is round in cross−section except at its polygonal base; specimens are slightly longer (central ray) than large (including lateral−ray outline), with a ratio varying from 1 to 1.5. Specimens cut longitudinally (Fig. 4 A) show an inner cavity along the central ray, subtriangular in section, bounded (except at the basal foramen) by a wall, ca. 30 µm thick. Remarks. — Some specimens of Chancelloria eros from the Lower Cambrian of the United States (Mehl 1996: fig. 1 D) and the Middle Cambrian of Australia (Mehl 1998: pl. 7: 7 – 8) show similar robust rays, although they have a distinct flat base and flat marginal rays, and the Cantabrian sclerites are prominently recurved. The morphology of the Cantabrian sclerites mimics that of paraclavules, interpreted as anchorate root−tuft spicules by Mehl (1996) in hexactinellids associated with dermal or gastral membranes (Mehl 1998), and is also similar to the siliceous spicules of Nabaviella Mostler and Mosleh−Yazdi, 1976 (sensu Bengtson et al. 1990). Nevertheless, they do not only differ in their composition (most probably secondarily phosphatized calcareous sclerites, not siliceous in origin) but also in the presence of basal foramina. Although some Late Cambrian – earliest Ordovician pelmatozoan holdfasts share close morphological similarities, their size, microstructure and inner cavities are different (Sumrall et al. 1997; Álvaro and Colchen 2002).	en	Clausen, Sébastien, Álvaro, J. Javier (2006): Skeletonized microfossils from the Lower-Middle Cambrian transition of the Cantabrian Mountains, northern Spain. Acta Palaeontologica Polonica 51 (2): 223-238, DOI: 10.5281/zenodo.13643839
03FD87F964540D028866FBBBFA3438F1.taxon	description	Fig. 4 C – E. Material. — More than 50 specimens preserved as phosphatic steinkerns in the Middle Cambrian “ Beleño ” facies, sections Cr 2 to Cr 4. Description. — Radially symmetrical sclerites with central vertical ray (up to 300 µm long), and 5 to 7 lateral rays lying on the same plane, which can be approximately of equal (ca. 300 µm) or variable (200 to 400 µm) length (though most distal parts of the rays probably eroded off). A broken specimen (Fig. 4 E) shows circular transverse sections of rays. Remarks. — The Cantabrian species is relatively similar to other previously described sclerites, such as those from the Early Cambrian of Southern Spain (Ossa−Morena Zone; Fernández−Remolar 2001: fig. 4 a, b) and Antarctica (Wrona 2004: fig. 6 j); and from the Middle Cambrian of Australia (Mehl 1998: pl. 7: 3); however, the lateral rays of the Cantabrian specimens lie on the same plane whereas they are clearly bent in the others. The sclerites referred to as Chancelloria sp. A above differ from Chancelloria sp. B. in the significantly larger central ray and prominently recurved lateral rays.	en	Clausen, Sébastien, Álvaro, J. Javier (2006): Skeletonized microfossils from the Lower-Middle Cambrian transition of the Cantabrian Mountains, northern Spain. Acta Palaeontologica Polonica 51 (2): 223-238, DOI: 10.5281/zenodo.13643839
03FD87F964540D028B2CFA32FE743829.taxon	materials_examined	Type species: Chancelloria eros Walcott, 1920; Burgess Shale, Middle Cambrian, British Columbia, Canada.	en	Clausen, Sébastien, Álvaro, J. Javier (2006): Skeletonized microfossils from the Lower-Middle Cambrian transition of the Cantabrian Mountains, northern Spain. Acta Palaeontologica Polonica 51 (2): 223-238, DOI: 10.5281/zenodo.13643839
03FD87F964540D028866F86DFB7539E7.taxon	materials_examined	Type species: Parazhijinites guizhouensis Qian and Yin, 1984; Meishucunian (Lower Cambrian), Guizhou, China.	en	Clausen, Sébastien, Álvaro, J. Javier (2006): Skeletonized microfossils from the Lower-Middle Cambrian transition of the Cantabrian Mountains, northern Spain. Acta Palaeontologica Polonica 51 (2): 223-238, DOI: 10.5281/zenodo.13643839
03FD87F964570D008B2CF894FD713D60.taxon	description	Fig. 4 F. Material. — Two phosphatic sclerites from the Middle Cambrian “ Beleño ” facies, section Cr 4. Description. — Elongate sclerites, subhexagonal in outline and posteriorly expanded (650 µm long and 400 µm wide), bilaterally symmetrical; anterior spine perpendicular to slightly bent at its extremity (400 µm long), with oval cross−section (160 µm in diameter), except at its tip where it is round; surface smooth. Remarks. — Bengtson et al. (1990) indicated that cambroclavids exhibit a wide morphological variability within the same scleritome, so that additional material seems necessary to complete the description and systematic assignment of the Cantabrian taxon. Parazhijinites guizhouensis shows a widespread morphological variability, and the most noticeable feature of this species is the elongate spine arising from a small base (Conway−Morris et al. 1997: 179). Although Conway Morris and Chen (1991) placed questionably Z. guizhouensis Qian and Yin, 1984 in synonymy with Z. longistriatus Qian, 1978, the former only differentiable by the presence of a slipper−like base and a very elongate spine, Conway Morris et al. (1997) reported them as separate species. The Cantabrian sclerites have all the characters visible in some Chinese sclerites of Meishucunian (Zhou et al. 2001: 212, fig. 4.2) to Atdabanian (Conway Morris et al. 1997) age. This paper reports the youngest occurrence of Parazhijinites within the lowest trilobite biozone of the Iberian Middle Cambrian.	en	Clausen, Sébastien, Álvaro, J. Javier (2006): Skeletonized microfossils from the Lower-Middle Cambrian transition of the Cantabrian Mountains, northern Spain. Acta Palaeontologica Polonica 51 (2): 223-238, DOI: 10.5281/zenodo.13643839
03FD87F964560D008B2CFBF5FD143A6D.taxon	materials_examined	Type species: Torellella laevigata (Linnarsson, 1871), by original designation, Lower Cambrian, Lugnås, Västergötland, Sweden.	en	Clausen, Sébastien, Álvaro, J. Javier (2006): Skeletonized microfossils from the Lower-Middle Cambrian transition of the Cantabrian Mountains, northern Spain. Acta Palaeontologica Polonica 51 (2): 223-238, DOI: 10.5281/zenodo.13643839
03FD87F964560D0E8866FA91FE863B9B.taxon	discussion	Remarks. — Qian and Xiao (1995) have recently proposed a relatively comprehensive hyolith classification (see English translation in Kruse 2002). Due to the lack of conchs associated with opercula, detailed suprageneric−level groupings will not be used herein. Operculum A Fig. 5 A – E. Material. — About 20 phosphatized opercula from the “ Beleño ” facies, section Cr 4. Description. — Operculum circular to slightly oval in outline, up to 0.6 mm in diameter; outer side strongly convex and smooth, with faint concentric growth lines, composed of a central, convex (sometimes almost hemispherical) area separated by a distinct depression from a peripheral band, corresponding to internal marginal zone and reaching ca. 1 / 10 of the diameter; well rounded apex (growth center) situated generally in the centre of the operculum or slightly excentric; inner (concave) side bearing a distinctly offset marginal zone, up to about 1 / 10 of the operculum diameter in width; paired cardinal processes prominent, crescent−shaped, symmetrically bounding internally the offset marginal zone, diverging at 30 – 40 ° at their most prominent edge, and reaching 4 / 5 of the diameter; clavicles absent. Remarks. — The Cantabrian operculum differs from Conotheca australiensis Bengtson (in Bengtson et al. 1990) and C. laurentiensis Landing and Bartowski, 1996 (respectively from the Lower Cambrian of Australia and Laurentia), in the absence of clavicle−like tubules. It differs also from Turcutheca? sp. A (Hinz 1987), from the Lower Cambrian of Shropshire (UK), in the crescent shape of the cardinal processes; from Sysoieva exilis Marek, Malinky and Geyer, 1997, from the Middle Cambrian Micmacca Breccia, in the shape of the cardinal processes (like wings of butterfields) and central termination of their lateral edges, attached to the interior surface and terminating in a central point; and from Neogloborilus hymenodes (Duan and Xiao in Qian et al. 2000), from the Lower Cambrian Yuertus Formation, Xinjiang (China), in the presence of a central elevated area (ca. 1 / 3 of the diameter) lacking a central apex on the convex side, and of paired cardinal processes bearing transverse faint constrictions on the concave side. As Marek (1963) pointed out that hyolith taxa should not be erected without complete information from both conch and operculum morphology, the present operculum is taxonomically unassigned.	en	Clausen, Sébastien, Álvaro, J. Javier (2006): Skeletonized microfossils from the Lower-Middle Cambrian transition of the Cantabrian Mountains, northern Spain. Acta Palaeontologica Polonica 51 (2): 223-238, DOI: 10.5281/zenodo.13643839
03FD87F964580D0D8866FEBBFDF43C24.taxon	description	Fig. 5 F, G. Etymology: After “ margarita ” (in Spanish, daisy), the broad aspect of the convex side of the sclerite. Type locality: Eastern Esla nappe, in the vicinity of the locality of Crémenes, Cantabrian Mountains, Spain. Type horizon: Up to 10 m above the base of the “ Beleño ” facies, upper member of the Láncara Formation. Holotype: Sclerite DGO 21146 (Fig. 5 G). Material. — Eight specimens from the “ Beleño ” facies, section Cr 4. Diagnosis. — Bilaterally symmetrical, concavo−convex sclerites, oval to subtrapezoidal in outline, bearing one prominent notch and two subduded domes on concave side, two distinct pits and radially symmetric folds or invaginations on anterolateral margins. Description. — Two faces, convex and concave, can be distinguished in these sclerites. One margin of the sclerite bears a prominent notch, and is here considered (by analogy with marginal notches of Wushichites; Conway Morris et al. 1997) as the posterior margin. On the convex face, the opposite (anterior) margin bears two symmetrical (perpendicular) folds or invaginations, which form prominent sulci on margin, and attenuate toward the centre. The lateral margins connecting both folds and the posterior notch are slightly convex−concave in a rounded sinuous pattern that also attenuates toward the centre. The anterior margin of the concave face bears two symmetrical domes with rounded tops, which correspond to the prolongation of the above−described folds, connected by a faint depression, the whole framework elevated above the rest of the face; the centre of the concave face is depressed anteriorly and laterally bounded by an amphitheatre−like wall. The lateral (concave upward) view of the sclerite is subtriangular, increasing in thickness toward the anterior margin, and bears two lateral pits (60 µm in outer diameter) in the wall at both anterolateral sides. Comparison. — Wushichites minutus and W. polyedrus were originally defined in Xinjiang (China) by Qian and Xiao (1984) as cambroclaves of uncertain affinity. Although Bengtson et al. (1990: 103) reported both taxa as “ doubtful species ” likely referable to the genus Cambroclavus, their morphological characters are so striking that it seems reasonable to place them in a separate genus (Conway Morris et al. 1997). These authors revised new material from the type area, and considered W. polyedrus to be a junior synonym of W. minutus. The presence of a prominent spine broadly transverse to the disc (Qian Yi 1989: 235) was the criterion for keeping Isoclavus and Wushichites separate (Conway Morris et al. 1997: 180). Holoplicatella differs from Wushichites sensu Conway Morris et al. (1997) in the presence of folds and lateral pits, and the broadly inflated (and not flattened) character of the sclerites.	en	Clausen, Sébastien, Álvaro, J. Javier (2006): Skeletonized microfossils from the Lower-Middle Cambrian transition of the Cantabrian Mountains, northern Spain. Acta Palaeontologica Polonica 51 (2): 223-238, DOI: 10.5281/zenodo.13643839
03FD87F9645B0D0D8B2CF9F7FD7638C5.taxon	materials_examined	Type species: Cantabria labyrinthica gen. et sp. nov. Etymology: After the Cantabrian Mountains, in which the fauna was sampled. Cantabria (feminine): enigmatic sclerite from the Cantabrian Mountains. Diagnosis. — As for the species (because of monotypy).	en	Clausen, Sébastien, Álvaro, J. Javier (2006): Skeletonized microfossils from the Lower-Middle Cambrian transition of the Cantabrian Mountains, northern Spain. Acta Palaeontologica Polonica 51 (2): 223-238, DOI: 10.5281/zenodo.13643839
03FD87F9645B0D0D8B2CFDB2FF663BE9.taxon	description	Fig. 5 H. Material. — One isolated specimen from the “ Beleño ” facies, section Cr 4. Description. — Bilaterally symmetric, concavoconvex sclerite, ca. 750 µm in diameter. The convex face of the sclerite is subcircular in outline, bearing two pairs of distinct symmetric folds on the anterolateral half of the face. The anterior margin of the concave side bears two lateral symmetric, sharp−pointed domes, which correspond to the prolongation of the above−described folds, connected by an offset marginal platform, U−shaped, and bounded by steep slopes. In lateral view, both domes and the platform are prolonged into a subtriangular face bearing a central pit, circular in outline and 120 µm in diameter. The posterior margin of the concave face is depressed, connected with the center of the concavity and with the steep slopes that bound the U−shaped offset marginal platform. The posterior margin is rounded and has no notch. Remarks. — Although the specimen is morphologically close to Holoplicatella margarita gen. et sp. nov, open nomenclature is preferred: Holoplicatella? sp. differs from P. margarita in the absence of a prominent notch on the posterior margin, and the presence of two pointed domes on the anterior margin and of a distinct pit on the anterior margin of the sclerite. These characters do not seem preservational artifacts and are maintained here as morphologically distinctive.	en	Clausen, Sébastien, Álvaro, J. Javier (2006): Skeletonized microfossils from the Lower-Middle Cambrian transition of the Cantabrian Mountains, northern Spain. Acta Palaeontologica Polonica 51 (2): 223-238, DOI: 10.5281/zenodo.13643839
03FD87F9645B0D0A8B2CF913FDF43BFE.taxon	description	Figs. 6 – 8. Etymology: After “ labyrinthine ”, the diagnostic character of the meshwork microstructure. Type locality: Eastern Esla nappe, in the vicinity of the locality of Crémenes, Cantabrian Mountains, Spain. Type horizon: Up to 10 m above the base of the “ Beleño ” facies, upper member of the Láncara Formation. Holotype: Plate DGO 21149 (Fig. 6 B). Material. — More than 100 specimens preserved as phosphatic sclerites in the “ Beleño ” facies, sections Cr 2 and Cr 4. Diagnosis. — Phosphatic sclerites, subcircular in outline and trapezoidal in cross−section, composed of a labyrinthine meshwork of tubes that centripetally increase in diameter and length; tubes interconnected by transverse smaller tubes; upper surface perforated by meshwork of holes, round to oval in shape. Description. — Phosphatic sclerites, subcircular in outline and trapezoidal in cross−section, with flat bottom, up to 0.8 mm in diameter and 0.2 mm thick, constructed of two parts: a framework forming a labyrinthine meshwork of tubes, and an upper surface making up the uppermost wall junctions of tubes; in some cases the latter is absent because of erosion or incomplete preservation. Edge of sclerites formed by peripheral girdle, completely perforated: holes 5 – 15 µm in diameter on bottom and lateral sides, and 50 – 200 µm on upper cap. Basal and lateral girdle rough containing grooves joining small perforations. Upper surface usually flat to slightly convex, perforated by meshwork of holes, round to oval in shape, highly variable in size (from 50 to 200 µm in diameter) but distinctly decreasing in size close to periphery; wall junctions between holes thin (ca. 30 – 35 µm) and smooth. Thin sections through sclerites (Fig. 7) reveal a complex internal structure, composed of a labyrinthine meshwork of tubes centripetally increasing in diameter and length by anastomosing their walls (Fig. 8); lowermost and lateral tubes randomly oriented, closed basally by thin hemispherical but perforated part of framework, passing upward into vertical, parallel and larger tubes, with annulated walls (Fig. 7 A, B, see also Fig. 6 D 1 – D 2). Tubes laterally perforated by transverse small synapticula−like tubes, up to 10 µm in diameter, connecting neighboring tubes (Fig. 7 E 3, see also Fig. 6 D 3). As a result, whole tube meshwork (and, originally, soft parts filling it) intercommunicating. Tube walls composed of two distinct apatitic layers, possibly diagenetic in origin (see discussion below), 0.25 – 0.3 µm thick (Fig. 7 E 2, E 3). Remarks. — Cantabria labyrinthica may be related to the eoconchariids based on the characters observed on the upper surface: the lack of protruding nodes or spines on the wall junctions separating the chaotic hole meshwork is a character shared by Fusuconcharium Hao and Shu, 1987. However, the holes of Microdictyon Bengtson, Matthews, and Missarzhevsky (in Missarzhevsky and Mambetov 1981), Fusuconcharium and Quadratapora Hao and Shu, 1987 (even if the two latter are considered synonyms of the former) can be both open and closed basally, are laterally unperforated, and continue as a single assemblage of parallel tubes through the plate, which has a bidimensional shape lacking a cup−shaped form. The labyrinthine microstructure of Cantabria can also be related to stereom microstructures (see e. g., Bengtson et al. 1990: fig. 174 A – C; Clausen and Smith 2005). Nevertheless, a labyrinthic stereom (Smith 1980: 12), which would be the most comparable known echinoderm−microstructure, consists of an unorganized mesh of trabeculae (which are not hollow) that behaves as a single crystal, whereas the meshwork of Cantabria is composed of (hollow) tubes with walls containing two distinct apatitic layers (Fig. 7 E 2, E 3), although this last character may be diagenetic. These skeletons were either originally phosphatic in composition or secondarily replaced by phosphate. However, the apatitic meshwork is not likely to represent phosphatic crusts lining trabeperforated parallel tubes labyrinthine meshwork culae and pores (external molds) as they have a constant wall thickness and both their inner and outer sides are ornamented with transverse crests (Fig. 6 C). In addition, although the “ Beleño ” facies is dominated by “ encrinitic ” (echinodermrich) packstone (see Álvaro et al. 2000 b), echinoderm ossicles are absent after etching as they were not secondarily phosphatized: phosphatization was selective and did not apparently affect stereoms. In summary, even if we interpret the described structure as a coated stereom, the preservation of the upper surface of the plates (Fig. 6 B, D) indicates that their tubes would from a stereom porosity and, therefore, the density, coarseness (sensu Smith, 1980) and structure would be quite different from other known stereom types. The taxonomic affinity of Cantabria is uncertain. Nevertheless, the similarities with eoconchariids (discussed above) suggest it might be considered as Middle Cambrian lobopodian external sclerites phylogenetically related to the Early Cambrian eoconchariids. However, new sclerites found in other outcrops, and eventually with other mineralogical composition, would help to improve this uncertain assignment. Stratigraphic and geographic range. — Lowermost Middle Cambrian “ Beleño ” facies, upper member of the Láncara Formation, eastern Esla nappe, in the vicinity of the locality of Crémenes, Cantabrian Mountains, Spain.	en	Clausen, Sébastien, Álvaro, J. Javier (2006): Skeletonized microfossils from the Lower-Middle Cambrian transition of the Cantabrian Mountains, northern Spain. Acta Palaeontologica Polonica 51 (2): 223-238, DOI: 10.5281/zenodo.13643839
