Chariocrinus japonicus, a new species of isocrinid crinoid (Articulata) from the Lower Cretaceous of Takayama City, central Japan
A specimen, originally described as ‘Pentacrinus’ from the Middle–Upper Jurassic of central Japan, is re-analysed and now recognised to be a new species of the genus Chariocrinus Hess, 1972, from the Lower Cretaceous. Chariocrinus japonicus sp. nov. has nine columnals per noditaxis, low columnal height, a pentalobate to sub-pentagonal articular facet and an impersistent median ridge on the latera. Chariocrinus was originally described from the Middle Jurassic of Switzerland, and has also been recognised from elsewhere in Europe, Antarctica and North America. The Japanese specimen represents the first report of Chariocrinus in the Cretaceous of Asia, thereby significantly extending both its temporal and eastern geographical range. This specimen suggests Chariocrinus had a global distribution and, as such, conforms with the distribution of other Mesozoic and modern isocrinine genera.
An Upper Jurassic Boreal echinoderm Lagerstätte from Janusfjellet, central Spitsbergen
Echinoderm ossicles have a high preservation potential as fossils. Their skeletons, however, disarticulate easily and rapidly after death, so they are relatively rare as articulated specimens. Because of the fragility of the echinoderm skeletons, preservation of complete specimens requires special conditions. Burial has to be rapid and effective enough to prevent subsequent disruption by currents or scavengers (Donovan 1991). Echinoderms are particularly sensitive to smothering by sediments, because this effectively blocks their water-vascular system. Following Seilacher (1970), the results of such events have been referred to as “obrution deposits”. Tempestites and turbidites have commonly been suggested as physical mechanisms for the creation of exceptionally wellpreserved assemblages known as Lagerstätten. Late Jurassic examples in Europe include the Solnhofen Plattenkalk of Bavaria (Hess 1999) and the French lithographic limestones of Cerin (Breton et al. 1994) and Canjuers (Roman et al. 1991, 1993, 1994). However, very few echinoderm fossils have until now been reported from high-latitude deposits.
A note on Hoploscaphites pungens (Binckhorst, 1861) (Cretaceous Ammonoidea)
Abstract Slicified specimens of the scaphitid ammonoid Hoploscaphites pungens (Binckhorst, 1861) are recorded from the basal part of the Gronsveld Member (Maastricht Formation, late Maastrichtian, Belemnitella junior Zone of authors), as exposed near the Maastrichtian stratotype section. This record significantly extends down the stratigraphic range of the species, which was previously thought to be confined to the Nekum Member of the "Maastricht tuffaceous chalk facies' and to the upper ammonite occurences in the Maastricht Formation are virtually restricted to indurated parts (e.g., hard-grounds) of the sequence. Refinement of the stratigraphic ranges of the various ammonite species is to be expected as fieldwork continues.