Note As explained in the section Discussion, the present material indicates that Palaeocomaster should be assigned to a separate family Palaeocomasteridae n. fam. in the Superfamily Comatuloidea rather than in Solanocrinitoidea. Summers et al. (2014) restored Comatulidae Fleming (1828) in place of Comasteridae Clark (1908), in accordance with ICZN Article 23.9. The corrected name has since been used in at least one other paper (Messing and Tay 2016). Correspondingly, diagnosis of Comasteroidea of the Revised Treatise (Hess and Messing 2011) is modified in the following.
Order Comatulida A. H. Clark 1908.
Superfamily Comatuloidea Fleming 1828.
Diagnosis Centrodorsal thick to thin discoidal or pentagonal, rarely stellate; aboral apex broad, cirrus-free, flat or slightly convex or concave, sometimes with narrow radiating interradial impressions (also in fossil Notocrinoidea); dorsal star absent, but center of aboral apex sometimes depressed; central cavity less than 40 % of centrodorsal diameter, larger in very small specimens; adoral surface with interradial furrows for basals, but no radial pits or coelomic impressions. Cirrus sockets generally rather large, without distinct ornament, crowded around centrodorsal margin in one to three irregular tiers, never forming vertical columns. Basis of cirrus sockets loosely connected in Palaeocomaster. Some species of Comatula, Comanthus, Comaster, Phanogenia and Capillaster with centrodorsal thin, reduced, commonly not projecting over exposed aboral surface of radials and bearing few or no cirri. Basal rosette unknown in Palaeocomaster but present in other genera; basals rod-shaped, with tips commonly exposed interradially. Subradial clefts may be present, especially in large specimens. Radials typically with short exposed surface, commonly concealed midradially or barely exposed interradially; rarely completely concealed; well exposed and trapezoidal in species with reduced centrodorsal; well exposed with tongue-like extensions separating bases of adjacent rays in paedomorphic Comatilia. Radial articular facet parallel to oral–aboral axis or nearly so and with shallow fossae. Interarticular ligament fossae large, high and wide, generally higher than aboral ligament fossa, and separated by broad and shallow midradial furrow, which is commonly constricted between muscle fossae. Adoral border of interarticular fossae straight or slightly curved, horizontal or slightly sloping. Adoral muscle fossae high in Palaeocomaster, low in other genera and forming narrow bands along horizontal adoral edge. Radial cavity large, with a spongy calcareous filling in living species. Rays divided at least at primibrachial 2, commonly up to several times more producing as many as 200 undivided arms. Synarthry or modified synarthry between primibrachials 1 and 2 and secundibrachials 1 and 2, either relatively featureless or resembling syzygies. True syzygies present only in Comatula. First pinnule on secundibrachial 2 (when series composed of 4 ossicles). Pinnulation incomplete only in Comatilia, which lacks several pinnules after the first pair. Oral pinnules slender, flagellate, of numerous short pinnulars. Distal pinnulars of at least some oral pinnules bearing a comb formed by peg- or blade-like teeth, one or two per pinnular. Similar combs present elsewhere only in some Heliometrinae (Antedonoidea). Middle and distal pinnules commonly extremely spiny. Arms arising farthest away from the eccentrically placed mouth (=posterior) commonly shorter than those arising closest to mouth, sometimes lacking ambulacral groove but with better developed gonads. Mouth typically displaced off center or marginal and anal papilla central or subcentral on disk (commonly less so in juveniles); mouth central or subcentral in Phanogenia, Palaeocomatella, Aphanocomaster, Comissia, Rowemissia and Comatilia.
Early Jurassic (Hettangian)––Holocene.
Palaeocomasteridae n. fam.
Diagnosis Centrodorsal with rather loosely aggregated tube-like bases of smooth cirrus sockets, sockets arranged in one to three irregular rows, interradial ridges not developed; centrodorsal cavity deep and sealed aborally by a thin plate, but open in less well-preserved specimens; width of cavity 15–25 % of centrodorsal diameter. Basals united in a star-shaped ring around the centrodorsal cavity, with narrow petals marginally crenulated; petals distinct or more or less fused to the centrodorsal.
Early Jurassic (Hettangian)––Late Jurassic (Kimmeridgian).
Palaeocomaster is the only genus of the family. Included species: P.styriacus Kristan-Tollmann 1988, Hettangian; P. morierei (de Loriol 1889 in 1882–1889), Pliensbachian; P. benthuyi Hess 2014a, Pliensbachian; P. paucicirrus Hess 2014a, Toarcian/Aalenian; P. schlumbergeri (de Loriol 1889 in 1882–1889), Bathonian; P. messingi Hess (2012), Bathonian; P. stellatus Gislén (1924), Bathonian; P. latiradius (Carpenter 1882), Bathonian; P. calloviensis (Carpenter 1882), Callovian; P. guirandi (de Loriol 1889 in 1882–1889), Oxfordian; P. musculosus Hess (2014b), Oxfordian; P. wurtembergicus (Carpenter 1881), Kimmeridgian.
Palaeocomaster Gislén 1924
Diagnosis See family
Palaeocomaster
structus n. sp., Figs. 3, 4, 5, and 6a.
Material Twelve centrodorsals or parts thereof were examined, two with attached basal circlet. Their diameter varies from about 2.5 mm (Fig. 3a) to 1 mm (Fig. 5c), and their height from 1.2 mm (Fig. 3a, b) to 0.4 mm (Figs. 5c, 6a). They range from the Serpentinum Chronozone (three specimens) to the Variabilis Chronozone (two specimens); seven specimens are from the Bifrons Chronozone. Apart from the type specimens, the material includes specimens MHNLM 2015.1.16 to 2015.1.23.
Holotype MHNLM 2015.1.12; centrodorsal, Fig. 3a.
Paratypes Centrodorsals with attached basal circlet, MHNLM 2015.1.13, fig. 3c (locus 490, Bifrons Chronozone), MHNLM 2015.1.14, fig. 5a, locus 293 (Variabilis Chronozone), MHNLM 2015.1.15, fig. 5b, locus 325 (Bifrons Chronozone).
Etymology Latin, struo, structus; for the stacked elements making up the centrodorsals.
Type locality and horizon Guérin quarry, Feuguerolles, Calvados, France, locus 489 of Marc Chesnier, bed T8/2, Bifrons Chronozone, early Toarcian, Early Jurassic.
Diagnosis Centrodorsal slightly conical, rounded pentagonal in outline, composed of several layers (nodals) that may be fused or preserved as one- to three-layered disks with through-going cavity and crenulated petals on each facet; adoral centrodorsal cavity roughly 20 % of centrodorsal diameter, up to 30 % in smaller specimens, aborally sealed in a juvenile specimen and probably also in intact adults. Adoral surface of individual disks with slightly concave impressions with weakly crenulated interradial petals; aboral surface similar, but petals may be less developed, with edges slightly crenulated. Basal circlet stellate, fused to centrodorsal; petals crenulated and broadly united around cavity. Depending on centrodorsal height, 2–5 elliptical cirrus sockets on each side; axial canal rectangular; cirral scars smooth or with slightly ornamented transverse ridge, part of rim weakly crenulated.
Description Of the twelve specimens described, all but one (Fig. 5b) have aboral opening only slightly smaller than adoral opening. The two best preserved specimens are also the largest (Figs. 3a, 5a). In the holotype (Fig. 3a), adoral and aboral sides appear similar, but centrodorsal is slightly conical (the aboral end is narrower). One centrodorsal is more or less intact (Fig. 5b) with aboral facet closed and irregular; adoral facet has three narrow, slightly concave petals fused to neighbouring bases of cirrus sockets. The second largest centrodorsal (Fig. 5a) bears basal circlet adorally, with only two rows of cirrus sockets and open aborally, suggesting that it is incomplete. Holotype centrodorsal (Fig. 3a) appears intact adorally, as indicated by regular petal structure, but not sealed aborally. However, aboral diameter of centrodorsal cavity is only about half that on adoral surface, as in relatively high centrodorsal (Fig. 3b), indicating that both centrodorsals are almost complete. Cirral scars are mostly smooth; axial canal is elliptical to rectangular and may be flanked by weak knobs (Figs. 3a3; 5a3) but no distinct transverse ridge. Two centrodorsals have basal circlet attached (Figs. 3c, 5a). In the paratype (Fig. 5a), petal-shaped basals are united interiorly, forming stellate circlet around central cavity. Basal circlet is fused here with centrodorsal, and standing out from its surface. Figure 3c illustrates similar situation but with three basal petals somewhat shorter and two much shorter than those on centrodorsal. The aboral surface commonly has interradial petals that may have crenulated edges, similar to those on the adoral surface, but less produced in most cases; the specimen in Fig. 6a has nearly equal petals. Almost all facets bear petals, indicating that the centrodorsal was formed by fusion of several nodals during ontogeny. Number of cirrus sockets on each nodal side depends on centrodorsal height and varies from five (holotype, Fig. 3a) to two in specimens preserved as a nodal (Figs. 4d, 5c–d, 6a). Centrodorsals with only one or two rows of cirrus sockets have similarly sized adoral and aboral openings (Figs. 3c; 4b–d; 5a, c–d; 6a), suggesting that they are incomplete. Presumably, one or more nodals making up the centrodorsal were lost post-mortem, indicating that they were not tightly fused in life. The cirral scars are mostly smooth; the axial canal is elliptical to rectangular, and it may be flanked by weak knobs (Figs. 3a3; 5 a3). However, a distinct transverse ridge is not developed. The rims of the scars may be weakly crenulated (Figs. 3b3, c3; 4b3, c3). The centrodorsals have a flat adoral surface with petals that are merged with adjoining bases of cirrus sockets on two opposing sides; on the other sides, the petals are free in two cases and partly free in another one. Thus, the petals are either embedded in produced bases of cirrus sockets or stand out against the bases (Fig. 3a2). Such a situation is also seen in other specimens (e.g. Fig. 4c). Petals that are slightly convex (Fig. 3c1) may match concave petals (Fig. 3b1) of presumably adjoining disks. Petals assumed to be from an interior surface of the centrodorsal all reach the central cavity. Two centrodorsals are preserved with attached basal circlet (Figs. 3c and 5a). In the paratype Fig. 5a, the petals are united around the central cavity in a closed basal ring. The basal circlet is here fused with the centrodorsal, and stands out from the surface. Such a situation also occurs in the specimen in Fig. 3c, but in this case three of the petals on the circlet are somewhat shorter than those on the centrodorsal, and two of them are much shorter.
Remarks The 12 specimens are thought to belong to a single species, although there are some differences, especially in the shape and crenulation of the petals. However, overall morphology, including the presence of one to three stacked nodals making up the slightly conical centrodorsal, is not in favour of the presence of several distinct species. Similar variability also occurs in other species of Palaeocomaster, e.g. in P. paucicirrus (Hess 2014a, fig. 5). The present species is similar to P. paucicirrus Hess (2014a) from the Toarcian/Aalenian of Quedlinburg. In the well-preserved specimens of P. paucicirrus, the aboral apex is closed and concave (Hess 2014a, fig. 5a–c). The attached basal circlet is superimposed on the centrodorsal and its petals are equally long; they also lack the crenulated margins of P. structus n. sp. The width of the cavity in the Quedlinburg specimens is 25 % of centrodorsal diameter in the holotype, but larger in another specimen; the number of cirrus sockets is two or three on each side of centrodorsal; they are more prominent and circular than those of P. structus n. sp. Specimens assigned to Palaeocomaster were described by Nicosia (1991) from the Late Sinemurian-Early Pliensbachian of Turkey. The material includes three conical centrodorsals with closely set cirrus sockets, a narrow axial canal and a closed aboral apex. The finds were not named, and this is also true of a pentagonal, low cup without centrodorsal. Simms (1988) described an intact five armed comatulid as Procomaster pentadactylus from the German Posidonienschiefer (Early Toarcian). Because the centrodorsal is concealed by roughly 25 robust cirri, the arrangement and scars of the cirrus sockets cannot be ascertained, although Simms assumed that they are arranged in 10 or 15 vertical rows. Since the cirrus sockets of the most complete specimen of the present species total 25 (holotype, Fig. 3a), it cannot be excluded that the forms are conspecific. However, P. pentadactylus with its centrodorsal diameter of perhaps 5 mm is larger than the holotype of P. structus n. sp., with only about half that diameter. P. pentadactylus has a crown height of 6 cm, and one may assume by analogy that P. structus n. sp. was smaller. Because the centrodorsal is not exposed, P. pentadactylus cannot be assigned to family, although Simms discussed a possible relationship with Atelecrinidae (note: at the time this family included five armed Atopocrinus now excluded from the family) and Solanocrinitidae in which unbranched arms also occur.
Superfamily Solanocrinitoidea Jaekel 1918.
Diagnosis Centrodorsal truncated conical to discoidal or columnar with cirrus-free aboral apex. Postlarval column with synarthrial articulations retained in adults of Thiolliericrinidae. Cirrus sockets arranged in 10–20 vertical columns or in a few irregular, marginal circles, reduced or obliterated in Thiolliericrinidae. Centrodorsal cavity very narrow. Basals stout, generally united, in Decameridae forming large rhombic plates surrounded by the radial circlet and forming bottom of large shallow radial cavity. In other families, basals rod-shaped, visible interradially or concealed. Radial cavity large. Arms undivided or divided at first or second primibrachial.
Early Jurassic (Pliensbachian)––Late Cretaceous (Coniacian).
Family Solanocrinitidae Jaekel 1918.
Diagnosis Aboral side of centrodorsal flat or concave, commonly rugose or with irregular furrows. Cirrus sockets closely placed, commonly large, arranged in 10–15 columns (exceptionally as many as 20). Stout rod-shaped basals commonly exposed interradially, meeting centrally without forming large plates in bottom of radial cavity. Adoral side of centrodorsal with radiating, commonly short coelomic furrows in at least some species of Comatulina but not in other genera, although secondary furrows along each side of the basal rods may occur in corroded specimens. Exposed surface of radials rather large to short or concealed. Interarticular ligament fossae and adoral muscle fossae generally low and wide, forming narrow bands in Solanocrinites and Comatulina but may be higher and triangular in Archaeometra. Rays undivided or divided at first or second primibrachial, exceptionally at second secundibrachial or more distally.
Early Jurassic (Pliensbachian)––Late Cretaceous (Coniacian). Genera: Solanocrinites Goldfuss 1829 in 1826–1833, Archaeometra Gislén 1924, Comatulina d’Orbigny 1852 in 1850–1852, Pachyantedon Jaekel 1891.
Solanocrinites Goldfuss 1829 (in 1826–1833).
Diagnosis See Hess and Messing 2011.
Solanocrinites
jagti n. sp., Fig. 6b.
Material Only the holotype.
Holotype MHNLM 2015.1.24; centrodorsal, Fig. 6b.
Etymology Dedicated to John W. M. Jagt for his work on echinoderms, particularly crinoids.
Type locality and horizon Guérin quarry, Feuguerolles, Calvados, France, locus 355 of Marc Chesnier, bed D1, Margaritatus Chronozone, late Pliensbachian, Early Jurassic.
Diagnosis Centrodorsal columnar, slightly conical, wider than tall and circular in cross section; central cavity narrow; sides with five interradial and five radial vertical ridges; cirrus sockets sunken, lacking any distinct articular features, in two irregular columns of 2–3 sockets per radial area; adoral side nearly flat, petals indistinct, fused with radial parts, and not produced; aboral apex slightly concave, unsculptured.
Remarks The ten projecting ridges are better seen from the aboral side because of the slightly conical shape of the centrodorsal. The centrodorsal cavity is filled by sediment but narrow; the adoral facet lacks produced interradial petals which seem to be fused with the radial parts. Available information supports assignment of the centrodorsal to Solanocrinites, making it the oldest representative of the genus. It differs from the Middle Jurassic S. voultensis Hess (2012) in having 10 distinct vertical ridges, 5 interradial and 5 radial. Similar ridges occur in the Upper Jurassic S. costatus Goldfuss and S. gresslyi (Étallon), see Hess and Messing (2011, fig. 38), and are characteristics of the genus.
Superfamily incertae sedis.
Family incertae sedis.
Andymetra Hess 2012.
Diagnosis See Hess 2012.
Andymetra
toarcensis n. sp., Fig. 7.
Material The holotype and specimen MHNLM 2015.1.31.
Holotype MHNLM 2015.1.25, centrodorsal, Fig. 7a.
Etymology Name formed in reference to the Toarcian age of the species.
Type locality and horizon Guérin quarry, Feuguerolles, Calvados, France, locus 425 of Marc Chesnier, bed T1bc, Tenuicostatum Chronozone, early Toarcian, Early Jurassic.
Diagnosis Centrodorsal low bowl-shaped, irregularly circular with strongly projecting cirrus sockets; adoral surface with crenulated interradial petals, narrow and flat to concave, partly fused medially with tubular bases of neighbouring, nascent cirrus sockets; cirrus sockets about 50, circular, deeply sunken, largely unsculptured, with small axial canal surrounded by faint rim; upper cirrus sockets developed as strongly outward-projecting tubes; width of cavity 16 % of centrodorsal diameter; aboral apex small, lacking cirrus sockets.
Description The two centrodorsals are of similar size and morphology. The better preserved holotype has a jagged outline due to some cirrus sockets projecting strongly outward. Sockets diminish in diameter aborally and are deeply sunken, except those in the uppermost (adoral) row. Second specimen (Fig. 7b) similar, but adoral side partly covered by sediment and not well preserved.
Remarks
Andymetra
toarcensis n. sp. differs from the Bathonian A. galei Hess (2012, fig. 10b) mainly by the jagged outline caused by the more strongly projecting cirrus sockets. A. galei also has larger and less sunken cirrus sockets. Upper Oxfordian A. donovani Hess (2014b) has an outline approaching that of Andymetra
toarcensis, but bears only 2–3 rows of sockets, despite its somewhat larger size (3 mm diameter vs. 2.4 mm in A. toarcensis n. sp.). In addition, the petals in A. donovani do not form a stellate ring fused to bases of flanking nascent cirrus sockets. The centrodorsal of Upper Oxfordian Semiometra petitclerci (Caillet 1923) shares deeply sunken cirrus sockets with A. toarcensis n. sp., but is lower, with more numerous sockets, and without the individualized adoral side sockets. The adoral surface of the present species is similar to that of S. petitclerci (see Caillet 1923, fig. 1b), but latter has narrow petals similar to those of A. donovani. Semiometra petitclerci is known from specimens with the distinctive radial circlet attached to the centrodorsal (Radwańska 2007, fig. 3); the aboral pole bears a dorsal star (see Radwańska 2007, pl. 1, fig. 1e–f). Because the radial circlet is so far unknown in the three species assigned to Andymetra, the relationship between the two genera must remain open. However, the occurrence of a hemispherical, bowl-shaped and densely cirrated centrodorsal in the Early Jurassic shows that an increase in the number of cirri was one of the main trends in comatulid radiation. This is confirmed by Spinimetra chesnieri n. g. et n. sp. described below.
Superfamily incertae sedis.
Family incertae sedis.
Spinimetra n. g.
Diagnosis Centrodorsal circular and cone shaped in the adult specimen, hemispherical in the juvenile specimen; adoral surface with basal circlet of narrow, marginally crenulated petals, merged with the five adjoining, nascent bases of cirrus sockets around centrodorsal cavity; width of cavity 16 % of centrodorsal diameter; cirrus sockets numerous, small, crowded and deeply sunken, with pronounced horseshoe-shaped rim, each side projecting outward and downward as a blunt triangular spine. Aboral apex nearly flat, about 20 % of centrodorsal diameter in holotype, with small opening on the aboral pole.
Etymology Latin, spina, spine or thorn, for the spiny appearance of the centrodorsal; metra is a suffix commonly used for comatulids.
Type species Spinimetra chesnieri n. sp.
Remarks Morphology of the densely cirrated, conical, spiny centrodorsal of Spinimetra is unique among Lower Jurassic comatulids and, indeed, among later fossil forms. Similar cirrus sockets are known from the extant Atopocrinus A. H. Clark, Family Atopocrinidae Messing 2011 in Hess and Messing 2011, and Superfamily uncertain (Hess and Messing 2011, fig. 37, 2b). An undescribed species of Atopocrinus shares with Spinimetra several potential synapomorphies (Messing, pers. comm. 2016). These include cirrus socket structure, pores between sockets connecting to centrodorsal cavity, and tube-shaped rudimentary sockets on the aboral surface flanking the narrow basals. Differences include the strong interradial ridges, unitary construction, and apparent lack of basal crenulae in the living Atopocrinus. The construction of the Spinimetra centrodorsal from multiple ‘nodals’ versus the unitary construction in Atopocrinus (with interradial ridges) seems a major evolutionary distinction above family level. Extant Atelecrinidae also share with Spinimetra and Atopocrinus a conical centrodorsal with similar sockets, but lack the pores and tube-shaped rudimentary sockets. Atelecrinidae also differ in having wedge-shaped basals that form an externally visible ring (Messing 2003, 2013).
Spinimetra chesnieri n. sp., Fig. 8.
Material Three centrodorsals, holotype and two additional, juvenile specimens MHNLM 2015.1.27 and 2015.1.28.
Holotype MHNLM 2015.1.26, centrodorsal, Fig. 8b.
Etymology Dedicated to Marc Chesnier who collected and carefully recorded the material.
Type locality and horizon Guérin quarry, Feuguerolles, Calvados, France, locus 358 of Marc Chesnier, bed T1a, Tenuicostatum Chronozone, early Toarcian, Early Jurassic.
Diagnosis See genus (monotypic).
Description of holotype. Outline in aboral view is regularly circular but jagged due to protruding socket spines; profile is conical with flattened apex. Sockets are crowded, about 100, with approximately 10 around aboral apex, increasing as irregular columns to 20 around adoral margin. Radial and interradial areas not differentiated. Adoral surface with five regular, rather narrow and marginally crenulated interradial petals that protrude, like the socket spines, beyond centrodorsal margin. Petals fused with adjacent bases of nascent cirrus sockets around centrodorsal cavity. Symplectial articulation between a petal and the underlying cirrus socket (Fig. 8 b3; arrow) suggests that petals are part of a basal circlet. From the two bases of cirrus sockets emerging in each radius between the petals, one is much smaller and superimposed on the larger one. Sockets are hourglass-shaped between angular lateral processes of centrodorsal rim, with small axial canal at narrowest point. Aboral apex is nearly flat, with small central orifice.
Description of smaller (juvenile) individuals. Centrodorsal outlines and profiles are irregular. Cirrus sockets number about 20 in two rows (Fig. 8c) or about 30 in four rows (Fig. 8a). Adoral petals are indistinct, especially in the smaller specimen.
Remarks
Andymetra differs from Spinimetra by larger, circular and shallow cirrus sockets. The Oxfordian Semiometra petitclerci (Caillet 1923) has a low, bowl-shaped centrodorsal; cirrus sockets have lateral tubercles but lack a horseshoe-shaped rim with spiny extensions (see Hess 2014b, fig. 11b; Radwańska 2007, pl. 1, fig. 1d). In contrast to the juvenile specimens (Fig. 8a, c), the aboral apex of the holotype has only a small opening. The smaller of the juvenile specimens (Fig. 8c) has only two rows of cirrus sockets and the openings are similar on both sides. The larger centrodorsal (Fig. 8a) has four rows of sockets and a smaller opening aborally. This suggests that the centrodorsal of Spinimetra was built from stacked parts, similar to Palaeocomaster structus n. sp. However, petals are less produced on the adoral side of the juveniles indicating a more coherent stereom. Apart from overall shape and arrangement of the cirrus sockets, the adoral side is basically similar in S. chesnieri n. sp., A. toarcensis n. sp. and Semiometra petitclerci.
Order Isocrinida Sieverts-Doreck 1952 in Moore, Lalicker & Fischer.
Diagnosis See Hess and Messing 2011.
Suborder Pentacrinitina Gray 1842.
Diagnosis See Hess 2014a.
Family Paracomatulidae Hess 1951.
Diagnosis See Hess 2014a.
Singillatimetra Hess 2012.
Diagnosis See Hess 2014a.
Singillatimetra
truncata n. sp., Fig. 9a.
Material Only the holotype.
Diagnosis Columnal centrodorsal-like, rather thick; axial canal narrow, interradial area star shaped, with coarsely crenulated petals widening outward; five cirrus sockets irregular, bulging and smooth, occupying whole height of ossicle, offset from radial midlines except in one ray. Cirral scars slightly concave, smooth. Both columnal facets similar.
Holotype MHNLM 2015.1.29, columnal, Fig. 9a.
Etymology
truncata, Latin, for the truncated interradial petals.
Type locality and horizon Guérin quarry, Feuguerolles, Calvados, France, locus 298 of Marc Chesnier, bed T3, Serpentinum Chronozone, early Toarcian, Early Jurassic.
Description Interradial petals are star shaped, widening outward and with coarsely crenulated margins. Radial areas between the petals are truncated, ending with a large cirrus socket offset from midline. Sockets are separated by cleft. One socket is conspicuously smaller. Both facets are similar; sockets pointing slightly upward toward one facet likely indicate it as proximal facet.
Remarks This columnal differs from that of S. inordinata Hess (2012) in having a star-shaped outline with truncated endings interrupted by clefts. The interradial petals are strongly produced on both facets. Assignment to Singillatimetra is based on the presence of large, bulging cirrus sockets offset from the radial midline, and a narrow axial canal on both facets. The columnal is somewhat similar to nodals of Pentacrinites, such as P. collenoti (de Loriol 1888 in 1882–1889), here figured for comparison (Fig. 9c). However, nodals of the latter have elliptical, protruding petals; and the area between the crenulated margins is strongly concave. The cirral scar has a transverse ridge thickened at both ends. In addition, P. collenoti has small internodals found mostly as single ossicles, but may also be attached to nodals (Fig. 9c).
Pentacrinitina Gray 1842.
Family incertae sedis.
Forcipicrinus n. g.
Etymology Latin, forceps, after the forceps-like aspect of the cirrus socket bases.
Diagnosis Columnal moderately thick, with five claw-like radial processes harbouring smooth, deeply sunken circular cirrus sockets; axial canal very narrow; one facet with raised, star-shaped interior part showing short blunted interradial petals bordered by some scattered crenulae; other facet flat and largely unsculptured.
Type species Forcipicrinus
normannicus n. sp.
Forcipicrinus
normannicus n. sp., Fig. 9b.
Material Only the holotype.
Holotype MHNLM 2015.1.30, columnal, Fig. 9b.
Etymology Latin, normannicus, for the occurrence in Normandy.
Type locality and horizon Guérin quarry, Feuguerolles, Calvados, France, locus 397 of Marc Chesnier, bed T8/1, Bifrons Chronozone, early Toarcian, Early Jurassic.
Diagnosis See genus (monotypic).
Description Columnal is dominated by five claw-like radial extensions supporting circular, sunken cirrus sockets. One facet (Figs. 9b, 2) slightly convex with rounded petals that do not reach clefts between processes; petals are bordered by few scattered granules. Other facet (Figs. 9b, 1) flat, with a few scattered granules; three sockets projecting slightly upward suggest this as adoral. Axial canal is very narrow on both facets.
Remarks The narrow axial canal and the similar aboral and adoral facets of the ossicle suggest that it is not a centrodorsal belonging to Comatulida but rather a columnal of Pentacrinitina. In contrast to Singillatimetra truncata n. sp. and S. inordinata Hess 2012, the cirrus sockets are not offset from the radial midlines, a character of Paracomatulidae and Pentacrinitidae (see Hess and Messing 2011). Thus, assignment to Pentacrinitina is tentative and to a specific family uncertain. Some columnals of Pentacrinites collenoti (de Loriol 1888 in 1882–1889) were also found in the same bed. Figure 9c shows a nodal with attached internodal, illustrating slightly offset cirrus sockets and a cirral scar with transverse ridge thickened at the ends, characteristic of Pentacrinites (Hess and Messing 2011, fig. 21i–k).
Family Pentacrinitidae Gray, 1842.
Pentacrinites collenoti (de Loriol, 1888 in 1882–1889), Fig. 9c.
Material Three isolated nodals and two nodals with attached internodals from locus 397.
Description Small nodal and attached internodal having star-shaped outline with well-developed interradial petals (Fig. 9c), internodal visible laterally. Petals concave, surrounded by crenulated rim, and leaving some space around the axial canal for an internodal. One petal somewhat smaller, with acute tip. Axial canal is rather wide, 12 % of nodal diameter. Internodal small; diameter and height about half those of nodal.
Remarks The small size and the prominent internodal suggest that the two specimens are juvenile. Similarly, small specimens were figured by de Loriol (1888, pl. 200, figs. 2 and 3). In adult columns of the species, internodals are not visible (de Loriol 1888, pl. 200, fig. 1). Species of Pentacrinites vary in internodal development. They are small and not visible on the outside of the column in Bajocian P. dargniesi Terquem and Jourdy 1869 (see Hess and Messing 2011, fig. 21j,k); in the Bajocian/Bathonian P. ausichi Hess 2012, nodals and internodals are of similar diameter although the internodals are lower.
