New early crown-group asteroids (Echinodermata; Triassic of Germany)

Migmaster angularis n. gen. n. sp. (Trichasteropsiidae, Forcipulatacea, Asteroidea) is described from the German Triassic Lower Muschelkalk of Anisian (Pelsonian) age, and new specimens ofTrichasteropsis bielertorum broaden understanding of this species. Phylogenetic events linking the stem groups, known only from Paleozoic rocks, with the crown group, known only from post-Paleozoic rocks, are problematic; the new fossils partially constrain phylogenetic changes associated with emergence of crown-group asteroids.      

Phylogeny and classification of the Asteroidea (Echinodermata)

Post-Palaeozoic asteroids share a large number of derived characters of the ambulacral column and the mouth frame, and constitute the crown group of the monophyletic group Asteroidea. This crown group is here called the Neoasteroidea (new subclass). The stem species of the crown group lived in the Permian or early Triassic and so the evolution of the asteroids parallels that of the echinoids. Character distribution within the Neoasteroidea, especially morphology of the skeleton, digestive system, larvae and tube feet, allows subdivision into four orders (Paxillosida, Notomyotida, Valvatida, Forcipulatida). The latter three orders possess the synapomorphy of suckered tube feet and are united as the Surculifera (new superorder); the Paxillosida are their primitive sister group. Palaeozoic asteroids represent the stem group of the class, and may be divided into plesions according to the order of appearance of synapomorphies with the crown group. Classification of Palaeozoic asteroids requires much further study. The appearance of new characters within the crown group asteroids, such as suckered tube feet, implies that these were absent in the stem group. The range of life-habits possible in Palaeozoic asteroids can thus be partly deduced from evidence provided by living asteroids. Palaeozoic asteroids are deduced to have lacked suckered tube feet and were presumably unable to evert the stomach; hence they were precluded from life on hard substrates and extraoral feeding on epifaunal organisms. It is suggested that they lived on soft substrates by deposit feeding, scavenging and predation on small benthos.     

Molecular phylogeny of the Valvatacea (Asteroidea: Echinodermata)

The Valvatacea is one the most ecologically important, taxonomically diverse, and widespread groups of post‐Palaeozoic (i.e. modern) Asteroidea. Classification within the group has been historically problematic. We present a comprehensively sampled, three‐gene (12S, 16S, early‐stage histone H3) molecular phylogenetic analysis of the Valvatacea. We include five of the six families within the Paxillosida, the monotypic Notomyotida, and 13 of the 16 families of the living Valvatida. The Solasteridae is removed from the Velatida (Spinulosacea) and joins the Ganeriidae and the Leilasteridae as members of the clade containing the Asterinidae. The Poraniidae is supported as the sister group to the large cluster of Valvatacea. Asteropseids and poraniids are phylogenetically distant, contrary to morphological evidence. Several goniasterid‐like ophidiasterids, such as Fromia and Neoferdina are supported as derived goniasterids rather than as Ophidiasteridae. The Benthopectinidae (Notomyotida) are supported as members of the Paxillosida as are two members of the Pseudarchasterinae that have traditionally been considered members of the Goniasteridae. Our data suggest that Antarctic valvataceans may be derived from sister taxa in adjacent regions. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, 161 , 769–788.     

The black layer in cephalopods from the German Muschelkalk (Triassic)

Thin, dark, probably phosphatic coatings were found on the dorsum in front of and sometimes behind the aperture of 50 specimens of Paraceratites and Ceratites (Ammonoidea) belonging to 14 species and subspecies and in three specimens of Germanonautilus , all from the Middle Triassic of Germany. The proportions, occurrences, position, outline, and preservation in fossil Nautiloidea and Ammonoidea (originally organic matter) of this structure support the hypothesis that it is homologous with the black layer in Recent Nautilus and Allonautilus . It is not yet possible to test whether these cephalopods show homologous styles of the development of these structures or whether the black layer can be identified in a common ancestor. In contrast to many ammonoids, Ceratites and Paraceratites , most Palaeozoic ammonoids, and some Mesozoic ammonoids probably did not have lower mandibles that were suitable for the closure of the aperture. They probably possessed a dorsally extending mantle (supracephalic mantle fold) and a hood, as in Recent Nautilus and Allonautilus , that was attached to the black layer. This interpretation is corroborated by a similar morphology of the black layer in an adult specimen of the nautilid Cenoceras from the South German Middle Jurassic and three specimens of Germanonautilus from the South German Middle Triassic (both Nautiloidea).     

Hettangian Asteriidae (Echinodermata: Asteroidea) from southern Germany: taxonomy,phylogeny and life habits

Germanasterias amplipapularia andHystrixasterias hettangiurnus are new genera and species of Asteriidae (Asteroidea: Forcipulatida) described from the Hettangian (lowest Jurassic) of southern Germany. They are among the oldest known relatively complete asteroids assignable to surviving families, yet they are remarkably similar to certain living species. Modern asteriids are efficient predators of sessile and slow-moving stoutly-armored mullusks, however much asteriid morphology is suggested to have originated with suspension-feeding habits. The lineage leading to the modern Forcipulatacea might have separated from that of the remainder of the modern asteroids as early as the Carboniferous.     

Remarkably preserved benthic organisms and their traces from a Middle Triassic (Muschelkalk) mud flat

Knaust, D. 2010: Remarkably preserved benthic organisms and their traces from a Middle Triassic (Muschelkalk) mud flat. Lethaia, Vol. 43, pp. 344–356. A new Fossil‐Lagerstätte is reported from the Middle Triassic of Germany, preserving Foraminifera, Nematoda, Platyhelminthes, Nemertea, Annelida and a range of Arthropoda together with their traces. This is the oldest fossil record of free‐living nematodes and turbellarians, and the first occurrence of nemerteans in the Mesozoic. The rare preservation of the benthic associations together with their traces is unique; especially the abundant occurrence of different phyla as meiofauna (organisms with shortest dimension between 0.06 and 1 mm) provides an insight into the palaeoecological conditions of a 240‐Ma‐old muddy tidal flat. The preservation of benthic animals at the termination of their traces offers the exclusive opportunity to assign producers to the trace fossils. The results show that the discussed phyla were already established in the early Mesozoic in a similar diversity and composition as in modern analogues. The new Fossil‐Lagerstätte has the potential to prove a number of soft‐bodied taxa immediately after the end‐Permian mass extinction, which has wide‐ranging implications for phylogenetic interpretations. □Benthos, soft‐bodied organisms, Fossil‐Lagerstätte, Muschelkalk, trace fossils, Triassic.     

The Class Asteroidea (Echinodermata): Fossils and the Base of the Crown Group

Because of limited research, a generally accepted hypothesishas not emerged for the phylogeny of the Asteroidea. The fossilrecord is a potential source of needed data, although fossilasteroids are rare, and they tend to be poorly preserved. Emphasis in the taxonomy of both recent and fossil asteroidshas been on characters visible from the exterior, and paleontologistshave sought to fit even the most ancient (i.e., Ordovician)specimens into taxonomic ordinal schemes devised for recentasteroids. Animal form and arrangement of body wall ossiclesof Paleozoic asteroids can be similar to those of younger species,thereby suggesting close affinities, yet ambulacral arrangementsindicate clear separation of Paleozoic stem groups from thecrown group. Traits taken from the ambulacral column that mark crown-groupasteroids include presence of dorsal podial pores (which allowedtransfer of the ampullae to the arm interior), an offset arrangementof ambulacrals on the adambulacrals, and increased complexityof the articulation structures between ambulacrals and adambulacrals.Transfer of ampullae to the arm interior provided protectionand more space for ampullae within the arm, as well as spacewithin the furrow and between the ambulacral and adambulacralossicles for elaboration of the soft tissues that enhance armmotion.     

The structure of the larval nervous system of Pisaster ochraceus (Echinodermata: Asteroidea)

Ultrastructural observations and glyoxilic acid-induced fluorescence of catecholamines indicate that tracts of axons lie at the base of the ciliary bands and run throughout their length in bipinnaria and brachiolaria larvae of Pisaster ochraceus. Two types of nerve cells occur at regular intervals within the ciliary bands. Type I nerve cells are associated with the axonal tracts, and type II nerve cells, which are ciliated, occur along the edge of the ciliary bands. Two prominent ganglia, which appear as accumulations of nerve cells and neuropile, occur on the lower lip of the larval mouth. Smaller ganglia occur irregularly throughout the ciliary band. Synapses were never clearly identified and were assumed to be unspecialized. Nervous tissues were also found associated with the esophageal muscles, the attachment organ, and the larval arms. Organization of the nervous system and its association with effectors suggest it controls swimming and feeding. Several similarities exist between the nervous systems of larval asteroids, larval echinoids, and adult echinoderms.     

Antarctic Starfish (Echinodermata, Asteroidea) from the ANDEEP3 expedition

This dataset includes information on sea stars collected during the ANDEEP3 expedition, which took place in 2005. The expedition focused on deep-sea stations in the Powell Basin and Weddell Sea.Sea stars were collected using an Agassiz trawl (3m, mesh-size 500µm), deployed in 16 stations during the ANTXXII/3 (ANDEEP3, PS72) expedition of the RV Polarstern. Sampling depth ranged from 1047 to 4931m. Trawling distance ranged from 731 to 3841m. The sampling area ranges from -41°S to -71°S (latitude) and from 0 to -65°W (longitude). A complete list of stations is available from the PANGAEA data system (http://www.pangaea.de/PHP/CruiseReports.php?b=Polarstern), including a cruise report (http://epic-reports.awi.de/3694/1/PE_72.pdf).The dataset includes 50 records, with individual counts ranging from 1-10, reaching a total of 132 specimens.The andeep3-Asteroidea is a unique dataset as it covers an under-explored region of the Southern Ocean, and that very little information was available regarding Antarctic deep-sea starfish. Before this study, most of the information available focused on starfish from shallower depths than 1000m. This dataset allowed to make unique observations, such as the fact that some species were only present at very high depths (Hymenaster crucifer, Hymenaster pellucidus, Hymenaster praecoquis, Psilaster charcoti, Freyella attenuata, Freyastera tuberculata, Styrachaster chuni and Vemaster sudatlanticus were all found below -3770m), while others displayed remarkable eurybathy, with very high depths amplitudes (Bathybiaster loripes (4842m), Lysasterias adeliae (4832m), Lophaster stellans (4752m), Cheiraster planeta (4708m), Eremicaster crassus (4626m), Lophaster gaini (4560m) and Ctenodiscus australis (4489m)).Even if the number of records is relatively small, the data bring many new insights on the taxonomic, bathymetric and geographic distributions of Southern starfish, covering a very large sampling zone. The dataset also brings to light six species, newly reported in the Southern Ocean.The quality of the data was controlled very thoroughly, by means of on-board Polarstern GPS systems, checking of identification by a renowned specialist (Prof. Michel Jangoux, Université Libre de Bruxelles), and matching to the Register of Antarctic Marine Species (RAMS) and World Register of Marine Species (WoRMS). The data is therefore fit for completing checklists, for inclusion in biodiversity patterns analysis, or niche modeling. It also nicely fills an information gap regarding deep-sea starfish from the Southern Ocean, for which data is very scarce at this time. The authors may be contacted if any additional information is needed before carrying out detailed biodiversity or biogeographic studies.     

Oysters and oyster-like bivalves from the Middle Triassic Muschelkalk of the Germanic Basin

Middle Triassic marine deposits of the Germanic Basin (Muschelkalk) record a significant proliferation of cementing bivalves from different families. Based on previously undescribed, excellently preserved material from the Willebadessen Member (late Anisian, Illyrian) of the Upper Muschelkalk Trochitenkalk Formation of Willebadessen (Germany), we propose the new genus Noetlingiconcha, type species N. speculostreum sp. nov., for strongly plicate prospondylids lacking auricles. The new genus differs from Terquemia and Enantiostreon in being plicate rather than costate, and from Newaagia in the absence of auricles. We demonstrate that N. speculostreum was invariably attached by its right valve, in contrast to an externally similar species from the Lower Muschelkalk Freudenstadt Formation (lower Anisian, Bithynian) that was exclusively cemented by its left valve and thus represents the geologically oldest known oyster species. Previous reports of amphi-pleurothetic cemented bivalve species from the Muschelkalk probably result from lumping together these two externally similar species. The constancy of sinistral attachment in the geologically oldest Ostreidae suggests that left-pleurothetic valve orientation was already established in the ancestry of this family. Palaeontological data are therefore in accordance with genetic and larval shell morphology analyses that identified Pterioidea as the sister taxon of Ostreoidea, because Pterioidea contains several Permian-Triassic genera with an anatomically lower left valve.     

The ultrastructural organization of the mature spermatozoon of Luidia clathrata (Say) (Echinodermata: Asteroidea)

The sperm of Luidia clathrata are morphologically typical of asteroid sperm. The head is spherical and contains the nucleus and acrosomal complex. The nucleus has an anterior indentation in which rests the acrosomal complex. There is no evidence of a centriolar fossa along the posterior border of the nucleus. The acrosome is a cup-shaped structure containing a less electron dense central region. The periacrosomal material is homogeneous in nature, and the subacrosomal specialization of the periacrosomal materials appear as bands of varying electron density. The middle piece is an annular band of mitochondria which surrounds the proximal and distal centrioles. The centrioles exhibit the typical nine triplet arrangement. Both the centrioles and the axoneme project to one side of the middle piece region. Associated with the distal centriole is an elaborate pericentriolar process.     

Agelacrinitid Edrioasteroidea (Echinodermata) from the Middle Devonian of the Eifel (Rhenish Massif, Germany)

The few isolated reports of agelacrinitid edrioasteroids (“Timeischytes”) from the Middle Devonian of the Eifel (Rhenish Massif, Germany) are revised. In this context, a specimen-rich but low-diversity edrioasteroid association is described from the threshold of the Eisen and Latistriatus Members of the Junkerberg Formation (Eifelian, Middle Devonian) of the Blankenheim Syncline. Predominantly, the autochthonously preserved edrioasteroids settled fixosessile-epibenthically on the frequent-occurring orthid brachiopod Schizophoria schnuri blankenheimensis and represent a wide spectrum of ontogenetic growth stages. They are associated with epibenthic brachiopods, microconchids, bryozoans, and auloporids—exemplifying synecological interactions. Roundish, shallow concavities with the shape and size of preserved adjacent edrioasteroids within encrusting colonies of the bryozoan Eostenopora clivosa are of special interest. It is suggested that the depressions represent former positions of the adjacent edrioasteroids. The new Bellastrella eifeliana n. gen. n. sp. is described, and genus Krama Bell, 1976 is reported from the Middle Devonian of Germany for the first time.     

New fossil insects from the Anisian (Lower to Middle Muschelkalk) from the Central European Basin (Germany and The Netherlands)

The Palaeozoic–Mesozoic transition is characterized not only by the most massive Phanerozoic mass extinction at the end of the Permian period, but also its extensive aftermath and a prolonged period of major biotal recovery during the succeeding Middle to Late Triassic. Particularly, Anisian insect species from units of the Lower to Middle Muschelkalk from the Central European Basin are rare. The specimens described here originated from the Anisian Wellenkalk facies (Lower Muschelkalk), Vossenveld Formation of the Winterswijk quarry, The Netherlands, and from the orbicularis Member (lowermost Middle Muschelkalk, Anisian) of Esperstedt near Querfurt (Saxony-Anhalt). Thus, the described insect remains from Winterwijk and Esperstedt expand our knowledge about Middle Triassic terrestrial arthropod communities and their palaeodiversity. A new species of Chauliodites (C. esperstedti sp. nov) is introduced.     

A chemical alarm response in Pycnopodia helianthoides (Echinodermata: Asteroidea)

Adult Pycnopodia helianthoides exhibit a classic alarm response, moving away from fragments and tissue fluid of the tube feet, pyloric caeca, and body wall of conspecific individuals.     

Skeletal morphology of the mud star,Ctenodiscus crispatus (Echinodermata: Asteroidea)

The morphology of the following eight major ossicle types is described and illustrated for the goniopectinid asteroid Ctenodiscus crispatus: terminal plates, superomarginal and inferomarginal ossicles, adambulacral and ambulacral ossicles, odontophores, oral intermediate plates, and superambulacral ossicles. Development, variation, and relationships with soft body-parts and with other ossicles are embphasized. Each ossicle type is distinguished by numerous structures related to its function and to articulation with adjoining skeletal elements. Because major structures (such as pustules, alveoli, and articulation surfaces) distinguishing ossicle types develop early during ontogeny, immature ossicles are readily identifiable. However, changes in form and orientation of these structures occur during ossicle growth. Ontogenetic changes are influenced by development of associated skeletal and soft parts. Ambulacral and adambulacral ossicles near the peristome are highly modified but retain the basic characteristics of structure and orientation which define these major types of skeletal elements.     

Re-evaluation of the Devonian family Helianthasteridae Gregory, 1899 (Asteroidea: Echinodermata)

Because of their taxonomic and morphologic diversity, the asteroids of the Lower Devonian Hunsrück Slate of Germany are important to both an understanding of the history of the class Asteroidea and to the interpretation of community evolution during the Paleozoic. Helianthaster Roemer, 1863, a large multiarmed Hunsrück asteroid, is redescribed. The Helianthasteridae Gregory is restricted to Helianthaster and Arkonaster Kesling, 1982 (Middle Devonian, Canada); Lepidasterella Schuchert is similar to the other two genera but known specimens are of poor quality and as a result the status of the genus is uncertain. Helianthaster is noteworthy in part because its size, multiarmed state, and presence of pedicellariae suggest certain crown-group genera, yet aspects of the arrangement of the ambulacral column are characteristic of the Paleozoic asteroid evolutionary grade. Neither Helianthaster nor other Hunsrück asteroids appear closely linked to the crown group; instead, functional patterns apparently re-emerged through time, although identification of specific behavior of ancient asteroids is difficult to impossible.      

Molecular phylogeny of the Forcipulatacea (Asteroidea: Echinodermata): systematics and biogeography

We present a comprehensively sampled three‐gene phylogeny of the monophyletic Forcipulatacea, one of three major lineages within the crown‐group Asteroidea. We present substantially more Southern Hemisphere and deep‐sea taxa than were sampled in previous molecular studies of this group. Morphologically distinct groups, such as the Brisingida and the Zoroasteridae, are upheld as monophyletic. Brisingida is supported as the derived sister group to the Asteriidae (restricted), rather than as a basal taxon. The Asteriidae is paraphyletic, and is broken up into the Stichasteridae and four primary asteriid clades: (1) a highly diverse boreal clade, containing members from the Arctic and sub‐Arctic in the Northern Hemisphere; (2) the genus Sclerasterias; (3) and (4) two sister clades that contain asteriids from the Antarctic and pantropical regions. The Stichasteridae, which was regarded as a synonym of the Asteriidae, is resurrected by our results, and represents the most diverse Southern Hemisphere forcipulatacean clade (although two deep‐sea stichasterid genera occur in the Northern Hemisphere). The Labidiasteridae is artificial, and should be synonymized into the Heliasteridae. The Pedicellasteridae is paraphyletic, with three separate clades containing pedicellasterid taxa emerging among the basal Forcipulatacea. Fossils and timing estimates from species‐level phylogeographic studies are consistent with prior phylogenetic hypotheses for the Forcipulatacea, suggesting diversification of basal taxa in the early Mesozoic, with some evidence for more widely distributed ranges from Cretacous taxa. Our analysis suggests a hypothesis of an older fauna present in the Antarctic during the Eocene, which was succeeded by a modern Antarctic fauna that is represented by the recently derived Antarctic Asteriidae and other forcipulatacean lineages. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, 162 , 646–660.     

A preliminary phylogeny of the Pterasteridae (Echinodermata,Asteroidea) and the first fossil record: Late Cretaceous of Germany and Belgium

The Pterasteridae comprises a diversified group of extant largely deep-sea starfishes. Generic diagnoses have been based classically on soft tissue characters and skeletal architecture. A preliminary phylogeny of sixteen extant species is here worked out by cladistic analysis. The resulting tree suggests monophyly of extant genera and the validity of dissociated plates for identification of genera. Fossil remains of Pterasteridae are here described for the first time. By comparison with extant species, all the skeletal remains from the lower Upper Campanian of Belgium and from the lower Maastrichtian of Germany are tentatively assigned to the genusPteraster. The fossil record of starfishes is poor, but the present Late Cretaceous pterasterids provide one more piece of evidence of the high diversity of starfishes during the Mesozoic. Known Late Cretaceous and Paleogene fossils are broadly similar, which suggests the end-Cretaceous extinction event did not cause major turnover in asteroid faunal composition. As suggested for other starfish groups, both the fossil record of deep-sea Pterasteridae in shelf settings and tree topology imply an onshore-offshore evolutionary trend.