Remark The following nomenclatural revisions and diagnoses refer to the Revised Crinoid Treatise (Hess and Messing 2011).
Repositories NMB Natural History Museum Basel (Switzerland), SMNS Staatliches Museum für Naturkunde, Stuttgart (Germany).
Order Isocrinida Sieverts-Doreck, 1952
Diagnosis See Hess and Messing (2011).
Suborder Pentacrinitina Gray, 1842
Diagnosis Cup with radials projecting downwards and basals overhanging the top of the column; in Paracomatula radials without projection and large exposed surface, basal circlet flat. Stellate circlet of basals articulating with column with pattern of narrow interradial petals bordered by short, uniform crenulae. Arms divided at primibrachial 2 and further divided several times; division at primibrachials and secundibrachials isotomous, succeeding divisions endotomous; in Paracomatula 10 undivided, long arms after primibrachial 2. Interradial plates present in Pentacrinitidae and continuing in numerous plates of high tegmen, or absent in Eocomatulidae and Paracomatulidae. Synarthry between primibrachials 1 and 2 and secundibrachials 1 and 2. Syzygies absent in Pentacrinitidae, but cryptosyzygies present in Eocomatulidae and Paracomatulidae where syzygies also occur. Highly cirriferous juvenile column with intercalated internodals in adults in Pentacrinitidae. Articular facet of columnals with narrow or elliptical to pyriform petals surrounded by a slightly crenulated edge and separated by large, more or less triangular, smooth or rugose radial areas. Column of Eocomatula and Paracomatula short, with at most a few columnals, some of which may be low and without cirri in Paracomatula; column of Eocomatula with nodals articulated by symplexy, in Paracomatula mostly by synostosis. Cirri commonly laterally compressed and long in Pentacrinites but shorter and more circular in Seirocrinus, thin and circular throughout in Paracomatula. Late Triassic (Norian)–Late Jurassic (Oxfordian).
Family Pentacrinitidae Gray, 1842
Diagnosis Radials large and projected outwards or downwards, lower edge of basals more or less curved downwards, overhanging the top of the column. Arms divided at primibrachial 2 and further divided several times; division at primibrachials and secundibrachials isotomous, succeeding divisions endotomous. Interradial plates present and continuing in numerous plates of high tegmen. Brachials with weakly developed muscle fossae in pseudoplanktonic species. Ligamentary brachial articulations absent or restricted to secundibrachials 6 and 7, additional ligamentary articulations present in Pentacrinites dargniesi. Highly cirriferous juvenile column that may become very long with intercalated internodals in adults, reaching more than 20 m in Seirocrinus. Cirri commonly laterally compressed and long in Pentacrinites but shorter and more circular in Seirocrinus although differences are smaller in juvenile specimens. Column with persistent alternation and indefinite intercalation of columnals, small intercolumnals may be concealed by nodals. Upper Triassic (Norian)—Upper Jurassic (Oxfordian).
Family Eocomatulidae Simms, 1988
Diagnosis Interradial plates absent. Cryptosyzygies common throughout arm, facets with numerous fine marginal culmina. Short, untapered column of nodals, retaining distinct symplectial articulum on terminal columnal with open axial canal. Upper Triassic (Norian)–Lower Jurassic (Pliensbachian).
Family Paracomatulidae Hess, 1951
Diagnosis Column centrodorsal-like, composed of closely united five-sided columnals, terminal columnal with sealed axial canal; single columnal in Singillatimetra. Cirrus sockets without profile, offset to either side of the radial midline and arranged in 5 or 10 columns. Stellate circlet of basals articulating with centrodorsal with pattern of narrow interradial petals bordered by short, uniform crenulae (as in column of Pentacrinites). Radials with large exposed surface, commonly recumbent or overhanging. Radial articular facet large and steep to almost vertical; adoral muscle fossae high. Rays divided once at primibrachial 2; synarthry between primibrachials 1 and 2 and secundibrachials 1 and 2; cryptosyzygy with numerous fine ridges between secundibrachials 3 and 4. Syzygies after secundibrachials 11 or 12 on approximately every fifth brachial and with a few coarse ridges. First pinnule on secundibrachial 2. Upper Triassic (Norian)–Upper Jurassic Oxfordian).
Paracomatula Hess, 1951
Diagnosis Centrodorsal-like column of variable segments, distal or proximal segments may be lower and without cirri, in P. morator two fused columnals with symplectial upper and lower facets. Upper Triassic (Norian)–Upper Jurassic (Oxfordian).
Singillatimetra Hess, 2012
Diagnosis (after Hess 2012). Centrodorsal of single element, asymmetrical in outline; 5 bulging cirrus sockets arranged irregularly; no radial cavity or axial canal visible; aboral and adoral sides similar, weakly sculptured, on aboral side irregular tubercles and weak radial impressions without crenulae, on adoral side narrow interradial bands with short crenulae for articulation to basals. Middle Jurassic (Bathonian).
Order Comatulida A.H. Clark, 1908
Superfamily Solanocrinitoidea Jaekel, 1918
Family Solanocrinitidae Jaekel, 1918
Palaeocomaster Gislén, 1924
Palaeocomaster paucicirrus n. sp., Fig. 5
Material Seven centrodorsals with basal circlet, ranging in diameter from 0.4 to 2 mm, are figured in Fig. 5a–g (SMNS 70107/1-7). Two postlarval centrodorsals and a broken small centrodorsal with basal circlet, similar to the specimen in Fig. 5f, are not figured. The comatulid material from Quedlinburg is part of a large collection of crinoids dominated by plicatocrinids (Cyrtocrinida) with the following species: Praetetracrinus inornatus Simms), P. doreckae Jäger and P. kutscheri Jäger; the millericrinid Shroshaecrinus? quedlinburgensis Jäger is also present; see Jäger 1995. Ophiuroids are common and were described by Kutscher (1996) who also collected the comatulid material.
Holotype Centrodorsal with basal circlet, Fig. 5a, SMNS 70107/1.
Etymology
paucus, L, for the few cirrus sockets on the centrodorsal.
Type locality and horizon. Quedlinburg, Upper Toarcian/Lower Aalenian (probably Aalensis Subzone), see Jäger (1995) and Kutscher (1996).
Diagnosis Small species. Centrodorsal with wide cavity, surrounded by stellate, prominent basal circlet fused to the centrodorsal; aboral apex flat and slightly rugose to convex and smooth; two or three circular and smooth cirrus sockets on each side, axial canal rectangular, nascent sockets not reaching periphery.
Description The centrodorsals are discoidal to slightly hemispherical in shape, the apex may be somewhat rugose, but is smooth and convex in one specimen (Fig. 5c). Two specimens are somewhat oval in outline; and the specimen in Fig. 5g seems to be distorted by some physical influence. The centrodorsal cavity is circular in the holotype and in specimen Fig. 5f, but oval in specimens Fig. 5b, c. The width of the cavity is 25 % of centrodorsal diameter in the holotype; in specimen Fig. 5c with roughly circular outline it is 45 % along one axis and 35 % along the other. The cavity is surrounded by the prominent stellate basal circlet that is fused with the centrodorsal. Weak sutures between centrodorsal and basal circlet are still seen in the specimens in Fig. 5b2, c1. The interradial extensions of the basals have weak furrows with finely crenulated margin. They extend to the periphery of the centrodorsal or beyond. Four juvenile specimens have a diameter of <0.5 mm, in three of them the centrodorsal cavity is sealed aborally (Fig. 5e), but in one (Fig. 5d) it is still open. The cirrus sockets are large, circular and smooth, with rectangular axial canal. Arrangement of the sockets is somewhat irregular, and they are displaced against each other. The holotype has three sockets on each side, one of them smaller, except in one radius with only two large sockets; the sides are separated by an interradial ridge. The facet of the smallest sockets reaches only halfway to the periphery. The other centrodorsals have only two sockets on each side, and one of them may be smaller; they lack interradial ridges.
Remarks The new species differs from the other Early Jurassic species of the genus (P. styriacus, P. morierei, and P. benthuyi n. sp.) by a different shape and a prominent basal circlet fused with the adoral facet of the centrodorsal. The Bathonian P. messingi has a narrower centrodorsal cavity and more numerous cirrus sockets, but the basal circlet is similarly fused with the centrodorsal. In the Oxfordian P. musculosus (see Hess 2013b) the centrodorsal cavity is wide, but the cirrus sockets are more numerous, and the aboral apex is distinctly sculptured. This species shares with P.
paucicirrus a stellate basal circlet extending beyond the periphery, although the basals may also be embedded in the radial circlet. P.
paucicirrus n. sp. seems to be more closely related to the Bathonian P. messingi and the Oxfordian P. musculosus than to the other Early Jurassic forms.
Palaeocomaster benthuyi n. sp., Fig. 4d
Material Only the holotype, a centrodorsal, is available.
Holotype Centrodorsal, NMB M10416, Fig. 4d.
Etymology Dedicated to Ben Thuy, for his recognition of the Sedan Lagerstätte and his work on ophiuroids.
Type locality and horizon Sedan, French Ardennes; late Early Pliensbachian, Davoei Zone, see Thuy et al. (2011).
Diagnosis Small species. Centrodorsal conical, without interradial ridges; adoral surface with concave, slightly crenulated interradial extensions for reception of the basals; diameter of centrodorsal cavity 25 % of centrodorsal diameter. Cirrus sockets large and smooth, slightly oval and protruding, arranged in two to three rows, without interradial ridges; axial canal rectangular.
Description The centrodorsal is conical, with protruding cirrus sockets extending to the apex. The largest sockets occur in the middle, smaller ones are close to the adoral side and around the apex. The centrodorsal cavity is wide; the adoral side is somewhat rugose and has interradial, concave extensions with slightly crenulated margins for attachment of the basals. The extensions are hardly demarcated from the base of the cirrus sockets; and they are interpreted as support for the basals.
Remarks The present centrodorsal has some resemblance with Palaeocomaster sp. from the Late Sinemurian/Early Pliensbachian of Turkey, represented by two small and a larger specimen (Nicosia 1991, fig. 43–44). In the figured Turkish specimen the cirrus sockets are also crowded and extend to the apex, but the shape is less conical and the cirrus sockets are more numerous, presumably the result of the larger size of the specimen that has a diameter of approximately 3 mm. However, the centrodorsal cavity is wider in P. benthuyi n. sp.