Late Cretaceous echinoderm ‘odds and ends’ from the Low Countries

From various levels within the Gulpen and Maastricht formations (upper lower to upper upper Maastrichtian, c. 69.5–66 Ma) in the extended type area of the Maastrichtian Stage (southeast Netherlands, northeast Belgium and the Aachen area in Germany), a few recent additions to echinoderm faunas are illustrated and briefly discussed. Added are some erratic, flint-preserved, pre-Maastrichtian echinoid taxa from Pleistocene fluvial gravel deposits; these are of palaeogeographical interest. Crinoids include the comatulid Semiometra saskiae with traces of sublethal predation and several bourgueticrinines. Amongst the latter, the species Dunnicrinus aequalis is found preserved in biocalcarenites as well as in flint, comprising a near-complete specimen with a spectacular, semiclosed crown and a number of dissolved thecae in nodules with flint-filled, 3D-preserved nerve canals. In addition, two types of bourgueticrinid holdfasts on echinoid tests are described. Amongst echinoids, cidaroid taxa such as Temnocidaris (T.) sp. 1, with preserved primary and scrobicular spines, and Temnocidaris (Stereocidaris) aff. arnaudi, are briefly discussed. Of special note is a near-complete, flattened test of Palaeodiadema (in a private collection) from the upper Maastricht Formation at Eben Emael (province of Liège, northeast Belgium); although no spines are associated, this specimen could well become an eye opener in diadematoid classification. Of Hemipneustes striatoradiatus, a number of tests with growth deformities (i.e., lack of one of the paired ambulacra, healed puncture wounds and apical depressions) and syn-vivo parasite infestation have been collected over recent years. Bite marks and healed puncture wounds on tests of Echinocorys spp. are recorded from the Vijlen and Lixhe 1 members (Gulpen Formation), in addition to bioerosional trace fossils produced by acrothoracican cirripedes and anomiid bivalves. Clusters of phymosomatid, holasteroid and spatangoid echinoids testify to obrution-induced mass mortality, possibly following(?)spawning. Added is the first record from the Maastrichtian type area of echinoid-produced traces (comparable to Scolicia), based on a slab from the basal Valkenburg Member; associated spatangoids comprise only members of the micrasterid genus Diplodetus. Of ophiuroids, a fairly rich material of Ophiomusium, or a closely related genus, is available from the Gronsveld, Emael and Meerssen members, preserving (partial) discs with arms attached that reveal all details of disc plating, mouth frame and arm structure. Asteroids include a (?)new astropectinid from the uppermost Gronsveld Member that appears to be distinct from Betelgeusia exposita, Aldebarania taberna and other paxillosidans on record from the area. This is preserved in life position, directly below a mass accumulation of both marine (sea grass) and terrestrial plants that testifies to a sudden event (obrution). A near-complete specimen of the goniasterid Chomataster acules, contained in a flint nodule, adds to our knowledge of this taxon by preliminary CT scanning. Pre-Maastrichtian, flint-preserved erratics include a test of Bathysalenia and isolated primary spines of Hirudocidaris. The former genus is known from the area, from lower upper Campanian strata (B. obnupta), but the apical disc and ambulacral plating of the present specimen appears to differ from that of both older (Turonian-Coniacian) populations of B. granulosa and the younger B. obnupta. The genus Hirudocidaris is unknown from the study area and, therefore, is assumed to have come from further afield (northwest France, southern Belgium).