Hans Hess

Myzostome Deformation on Arms of the Early Jurassic Crinoid Balanocrinus gracilis (Charlesworth)

Abstract Myzostome galls on arms of the Early Jurassic (Pliensbachian) Balanocrinus gracilis provide the first unequivocal evidence of such parasitic infestation in a post-Paleozoic crinoid.

Crinoids from the Middle Jurassic (Bajocian–Lower Callovian) of Ardèche, France

Several Middle Jurassic outcrops in the Ardèche Department near La Voulte-sur-Rhône and St-Étienne-de-Boulogne are rich in the remains of crinoids, but these were known from surface collections only and were not described using present standards of systematics. This paper brings the taxonomic status of the previously described crinoids up to date, reassesses the systematic position of some of the species based on cups and describes new forms. Sampling and washing of bulk material from the Lower Bathonian of the La Pouza locality yielded nearly 100,000 crinoid ossicles. Among them are rare comatulids with the following recognized as new: Andymetragalei n. g., n. sp., Palaeocomaster messingi n. sp., Singillatimetra inordinata n. g., n. sp. and Solanocrinitesvoultensis n. sp. These forms supplement the meagre record of Middle Jurassic comatulids and indicate that this group radiated well before the Late Jurassic. The Cyrtocrinida constitute the bulk of the crinoids and they are dominated by Cyrtocrinus praenutans n. sp. from which nearly all parts of the skeleton are described in their morphological variability. The La Pouza site furnished the additional new cyrtocrinids, Praetetracrinus bathonicus n. sp. and Phyllocrinusvoultensis n. sp. The material also includes numerous remains of the isocrinids Isocrinus dumortieri (de Loriol), Balanocrinus dumortieride Loriol, Balanocrinus pacomeide Loriol and Balanocrinus inornatus (d’Orbigny), which are described in some detail, including brachials. From the Upper Bajocian–Lower Bathonian locality of Pont des Étoiles, Pentacrinites ausichi n. sp. and the cyrtocrinid Scutellacrinus tenuis n. g., n. sp. are new to science. The results demonstrate that the Middle Jurassic crinoids from the Ardèche are one of the important and diverse Mesozoic crinoid faunas. Some forms bridge the gap between the Early Jurassic and the Late Jurassic hardground faunas of cyrtocrinids. Cyrtocrinus praenutans n. sp., a form similar to Cyrtocrinus nutans (Goldfuss) from the Oxfordian, is described as a separate species despite some overlapping phenotypic variability of cups and columnals. Pathological deformations on all types of ossicles of C. praenutans n. sp. are ascribed to the epizoan commensal Oichnus paraboloides Bromley. Different species are dominant at the different Bathonian localities, namely C. praenutans n. sp. at La Pouza and Phyllocrinus fenestratus (Dumortier) and Lonchocrinus dumortieri (de Loriol) at La Clapouze. Preservation and rock formation of the Upper Bajocian–Lower Bathonian Isocrinus nicoleti (Thurmann) at Pont des Étoiles suggests that this form lived in rather shallow and turbulent water. The dominance of cyrtocrinids and the presence of all growth stages and parts of the skeleton at La Pouza and La Clapouze suggest a deeper palaeoenvironment, with some transport of the ossicles.

Crinoids from the Shenley Limestone (Albian) of Leighton Buzzard, Bedfordshire, UK

A diverse and exceptionally preserved crinoid fauna is described from the Early Albian (Leymeriella tardefurcata Zone) Shenley Limestone of Leighton Buzzard (Bedfordshire, England). It is unusual in the presence of a number of species which are the last records of genera common in and typical of the Jurassic (the isocrinid Balanocrinus smithi sp. nov., the millericrinids Apiocrinites gillieroni (de Loriol) and an unnamed species of Apiocrinites, and the cyclocrinid Cyclocrinus variolarius (Seeley)), in association with the first record of the typically Cretaceous Roveacrinidae (Discocrinus integer sp. nov.). Sclerocrinids (Cyrtocrinida) are represented by Torynocinus canon and Torynocrinus globosus sp. nov. The excellent preservation of the material permits new and taxonomically important observations to be made on cup structure in the sclerocrinid and roveacrinid species, and the first description of Torynocrinus brachials. Additionally, the material includes different growth stages and brachials which allow for extended diagnoses of known species. The fauna is also remarkable for the association of differently sized stalked crinoids attached either by cirri or holdfasts, and a pelagic roveacrinid.

The crinoid Eugeniacrinites cariophilites from the Late Jurassic of southern Germany: babies, cripples and enigmatic wing plates

The material for the present paper is based on 50xa0kg of processed sediment from the Early Kimmeridgian of Geisingen. The most frequent crinoids comprise cups and brachials of the roveacrinid Saccocoma quenstedti while Crassicomafeifeli is represented by a few cups only; these remains are not described. Cups and primibrachials of Eugeniacrinitescariophilites are the commonest cyrtocrinids, while cups of Pilocrinus moussoni are rather rare and not further treated, as are columnals of the two species. The ontogenetic series of cups and axillary primibrachials of E.cariophilites starts from ossicles of about 0.5xa0mm in height; and growth is allometric in both types. Postlarval cups resemble phyllocrinids; the distinctive shape with lanceolate interradial extensions and wide articular facets appears at a later stage. The spearhead-shaped axillary primibrachials are synapomorphic. The youngest of these ossicles with a muscular facet proximally were able to form a flat roof over the radial cavity. First primibrachials with synostosial distal facet appeared at a slightly later stage with a width of 1xa0mm; growth is isometric. A significant number of cups are mutilated by bite marks. The predatory attacks were sublethal in most cases as shown by secondary stereom growth and regenerated facets. First primibrachials are not deformed, but deformations occur in a small number of second primibrachials. The results suggest that the predators, presumably fishes, targeted the soft parts in the cup. Enigmatic brachials with a large wing to one side and a facet to an arm are thought to belong to E. cariophilites and presumably attached to deformed cups; the wings may have been an antipredatory adaptation providing some shelter to the cup. The various antipredator morphologies in cyrtocrinid history are discussed. The presently available growth series of Eugeniacrinites invites discussion of early cyrtocrinid phylogeny. Eugeniacrinites seems to have been derived from Phyllocrinidae; and Sclerocrinidae with Cyrtocrinus as the first representative in the Middle Jurassic is thought to have originated from Early Jurassic Tetracrinidae such as Bilecicrinus.

Origin and radiation of the comatulids (Crinoidea) in the Jurassic

The early history of the comatulids is discussed based on recently described Jurassic specimens. Their centrodorsals suggest that the Order Comatulida is a monophyletic, synapomorphic clade that originated with Palaeocomaster from stem group pentacrinitids and not from a paracomatulid ancestor. A pentacrinitid is also considered ancestor to Paracomatula. As a result Paracomatulidae are classified with Pentacrinitina, making Paracomatuloidea redundant as a suborder of Comatulida. Palaeocomaster paucicirrus n. sp. from the Toarcian/Aalenian of Quedlinburg, northern Germany, and Palaeocomaster benthuyi n. sp. from the Pliensbachian of Sedan, France, are described as new.

Roveacrinids (Crinoidea) from the mid-Cretaceous of Texas: ontogeny, phylogeny, functional morphology and lifestyle

New material of known roveacrinids from two Cretaceous sites in Texas is described. Upper Albian strata at Saginaw Quarry furnished rich material of Poecilocrinus latealatus and Roveacrinus pyramidalis; for these two forms cups can be combined with primibrachials and secundibrachials. Some cups of Orthogonocrinus apertus are also present. Juvenile cups of these three species demonstrate ontogenetic changes, which are most prominent in P. latealatus. At the adult stage this species has cups with dish-like lateral wings; the first primibrachials have an aboral bowl; axillary second primibrachials and proximal secundibrachials have a wide aboral bowl; and distal brachials carry spines. The arms lack pinnules. A pelagic lifestyle with a mouth-up position is assumed. In contrast, R. pyramidalis has rod-shaped or stick-like brachials without wings, and food grooves are lacking. The less rich lower Cenomanian strata at the Dottie Lynn site provided a number of cups and brachials of Roveacrinus spinosus. In addition, cups of R. peracutus and R. alatus are present. Styracocrinus Peck is considered synonymous with Roveacrinus Douglas. The double cavity in the cups of the various species is discussed; its proposed function as a hydrostatic organ seems conjectural. Two genera of Saccocominae of the Late Jurassic radiation are thought to be ancestors to similar genera of Roveacrinidae first appearing during the Albian radiation. Derivation of Poecilocrinus may be from Saccocoma, Discocrinus and Plotocrinus possibly from Crassicoma. The ancestry of species of Roveacrinus and Orthogonocrinus with conical cups and two distinct body chambers is unclear. The closely similar juvenile cups of Roveacrinus pyramidalis and Poecilocrinus latealatus suggest a common origin despite the widely diverging arm structure. A comparison of Roveacrinus pyramidalis with the Triassic somphocrinid Osteocrinus reveals similar rod-shaped, smooth and tall brachials lacking a distinct food groove. Based on their mass occurrence and wide distribution, species of Osteocrinus species are thought to have been pelagic. This is substantiated by the presence of cups and rod-shaped brachials in Ladinian black shales of southern China. While food of species of Poecilocrinus presumably consisted of coccolithophores and planktonic foraminifera, collection and transport of food particles by Roveacrinuspyramidalis is enigmatic, as is that of Osteocrinus.

Balanocrinus and other crinoids from Late Jurassic mudstones of France and Switzerland

Late Jurassic mudstones of France and Switzerland are rich in remains of the isocrinid Balanocrinus. From the early Late Oxfordian of Savigna (Département du Jura, France) Balanocrinus brachiospina is described as new; the material includes all growth stages and skeletal elements, allowing the reconstruction of the animal and description of ontogenetic changes. The remains of Balanocrinus from Savigna are compared with Balanocrinus subteres (Münster in Goldfuss) from the Middle Oxfordian sponge facies of Holderbank (northern Switzerland) and with Balanocrinus pentagonalis (Goldfuss) from the Early Oxfordian of Les Rouges-Terres (Canton of Jura, Switzerland. The present material enables improved diagnoses of the two common Oxfordian species, B. subteres and B. pentagonalis. The Savigna locality includes two rare new comatulids, Palaeocomaster musculosus n. sp. and Andymetra donovani n. sp. The late Early Oxfordian locality of Andelot-Morval near Saint-Amour (Département du Jura, France) furnished B. brachiospina n. sp., and the comatulids are represented by Palaeocomaster musculosus n. sp., Archaeometra scrobiculata (Goldfuss) and Semiometra petitclerci (Caillet). The paracomatulid Paracomatula morator n. sp. from Andelot is the last representative of the group. Numerous remains of the cyrtocrinid Tetracrinus galei n. sp. supplement the Andelot fauna.

Roveacrinida (Crinoidea) from Late Triassic (early Carnian) black shales of Southwest China

Rich material of a tiny pelagic roveacrinid from the lower member of the Carnian Xiaowa Formation, Guanling area (Guizhou Province, Southwest China), is described. The remains are assigned to a distinct species, Osteocrinus sinensis n. sp. The species is characterised by an aboral element of variable length, a radial circlet forming a small cup and unusually long arms with hollow brachials grouped in pairs. This morphology is unique among crinoids. The remains settled partly articulated on the seafloor. Coprolites comprised of roveacrinid remains and apparently produced by ammonites are common, corroborating a pelagic lifestyle of the roveacrinids. An overview of previously described species of Osteocrinus is given; the present material contributes recognising variability and growth stages of the partly insufficiently known forms.

Balanocrinus (Crinoidea) from the Jurassic: species concept, reconstruction, ontogeny, taphonomy and ecology

Early and Late Jurassic mudstones of Europe are rich in remains of the isocrinid Balanocrinus. Recently collected material from the Early Pliensbachian of Sedan (France), from the Oxfordian of Andelot-Morval and Savigna (Département du Jura, France), and Les Rouges-Terres (Canton of Jura, Switzerland) adds significantly to the knowledge of the most important Jurassic species. The Oxfordian faunas that also include isocrinids, comatulids and a cyrtocrinid are the subject of a parallel publication. In the present paper intact specimens of Balanocrinus gracilis (Charlesworth) from Sedan, including early growth stages, and early ontogenetic stages of Balanocrinus brachiospina Hess from Savigna are described. The material from Savigna allows reconstruction of the animal and a comparison with the type species, Balanocrinus subteres (Münster in Goldfuss), for which columnals from the Middle Oxfordian sponge facies of Holderbank (northern Switzerland) and cup plates previously described from Germany are used. The taphonomy and palaeoecology of Balanocrinus occurrences in mudstones of Early to Late Jurassic localities of England, France and Germany are discussed and compared with beds of Chariocrinus from the Early and Middle Jurassic of Switzerland.

Extraordinary diversity of feather stars (Echinodermata: Crinoidea: Comatulida) from a Lower Jurassic (Pliensbachian–Toarcian) rock reef of Feuguerolles (Normandy, France)

Comatulid feather stars are rare fossils in the Early Jurassic, providing only patchy insights into the early evolution of the group. Here, we describe new finds of comatulids from the late Pliensbachian to late Toarcian of Feuguerolles, Calvados, France. They include new species belonging to four superfamilies. The dominant genus is Palaeocomaster, with P. structus n. sp. represented by centrodorsals. For Palaeocomaster, the family Palaeocomasteridae n. fam. is proposed; it is placed in the Superfamily Comatuloidea. Solanocrinites is represented by S. jagti n. sp. The new taxa Andymetra toarcensis n. sp. and Spinimetra chesnieri n. g. et n. sp. are Family incertae sedis. The diagnoses of Comatuloidea and Solanocrinitoidea are modified based on the new material. The paracomatulid Singillatimetratruncata n. sp. is represented by a columnal, as is Forcipicrinusnormannicus n. g. et n. sp. tentatively assigned to Pentacrinitina, Family incertae sedis. The material indicates that an important early comatulid radiation took place prior to the Toarcian Oceanic Anoxic Event, creating some basic types of these free-living crinoids. Along with the stratigraphic distribution patterns of the co-occurring stalked crinoids including the isocrinids Pentacrinitescollenoti, Isocrinus (Chladocrinus) basaltiformis, the millericrinid Amaltheocrinusamalthei, and the cyrtocrinids Cotylederma docens, Eudesicrinus mayalis, Praetetracrinusinornatus, Sacariacrinus n. sp. and Tetracrinus n. sp., the new feather star finds suggest that the Toarcian Oceanic Anoxic Event was not of major influence to crinoid diversity.