Intrastratal trace fossil zonation,Cretaceous flysch of northern California

Dissection of fine‐grained turbidites within the Franciscan complex at Trinidad Harbor reveals intrastratal zonation of biogenic structures. The pre‐depositional association comprises only three ichnotaxa (preserved in convex hyporelief) and is less diverse than the tiered post‐depositional association (comprised by at least seven ichnotaxa preserved in full relief). The latter association is dominated by Melatercichnus (n. ichnogen.). Post‐depositional trace‐makers exploited abundant plant detritus deposited with the turbidite sand. Temporal alternation of trace fossil associations resulted from the infrequent, but catastrophic, disturbance of pre‐turbidite communities and local replacement by assemblies of opportunistic organisms. Although probably short‐lived at specific sites, the post‐turbidite infauna was tiered, enabling a variety of deposit feeders to harvest phytodetritus of varied size or density simultaneously at different depths within newly deposited turbidite sand layers.     

Trace fossils from the Podhale Flysch Basin, Poland - an example of ecologically-based lithocorrelation

Certain ichnogenera from the Podhale Flysch Basin do not occur randomly, but are grouped in distinct horizons, which are useful in mapping. The position of certain tuffite beds proves an approximate isochronism of those trace fossil horizons. Changes of the life conditions, among them especially oxygenation of the sea bottom, were responsible for that ichnologic differentiation. Profuse Occurrences of Taphrhelminthopsis are mainly connected with the presence of lighter, bluish shales, which indicates a well-oxygenated bottom. More distal and frequent sedimentation of turbidites could positively influence the preser-vational potential of the surface forms (very good state of preservation of Taphrhelminthopsis suggests that preservation of surface forms was frequent in the flysch basin), but the O₂ condition was the main controlling factor for the occurrences of ichnofauna. Most discriminating were trace makers of pre-depositional (mud-dwelling) Taphrhelminthopsis , and they were most probably irregular echinoids, while soft-bodied trace makers of pre- and post-depositional Planolites (post-depositional means sand-dwellers) were the most tolerant ones. An increased level of biological activity connected with a shift in the OMZ could have been the reason why Taphrhelminthopsis became so profuse in one period. Concerning preservational problems, some complications in determining pre- and post-depositional forms in the case of composite beds are presented.     

First beetle elytra,abdomen (Coleoptera) and a mine trace from Lunz (Carnian,Late Triassic,Lunz‐am‐See,Austria) and their taphonomical and evolutionary aspects

Abstract: Four new species of Permosynidae are described: Platycrossus caroli Ponomarenko in Meller et al. sp. nov., Hydrobiites handlirschi Ponomarenko in Meller et al. sp. nov., Ademosyne polyzetete Ponomarenko in Meller et al. sp. nov. and Diarcuipenna bennettitophila Ponomarenko in Meller et al. sp. nov. Together with one polyphagous abdomen, they represent the first beetle remains from the Lunz formation, known for its richness in bennettite and cycad leaf remains and also for the bennettite reproductive organs. Furthermore, the first insect mine trace on a Nilssonia leaf segment is described, which is one of the most ancient linear mine traces. The rareness of insect remains in the plant‐bearing layers of the Lunz formation is still an enigma from the taphonomical–chemical point of view. The palaeoentomological and palaeobotanical considerations tentatively indicate a relationship between the rare occurrence of coniferous plants and the evolution or radiation of phytophagous insects during this time.     

A Nereites ichnofacies from the Ordovician‐Silurian Welsh Basin

The sediments of the Ordovician‐Silurian succession of west Wales are interpreted as turbiditic sands with associated pelagic and hemi‐pelagic mudstones. The strata contain a trace fossil assemblage consisting of fifteen ichnogenera, namely: Chondrites, Circulichnis, Cochlichnus, Cosmorhaphe, Desmograpton, Gordia, Helminthoida, Helminthopsis, Neonereites, Nereites, Paleodictyon, Palaeophycus, Planolites, Protopaleodictyon and Spirophycus. The ichnofaunal assemblage is typical of the Nereites ichnofacies. Twenty three ichno‐species are described, two of which (Helminthoida granulata, Palaeophycus serratus) are new. Turbiditic sands contain the most abundant and diverse ichnoassemblages, a reflection of favorable environmental conditions for habitation by benthic organisms. Both the turbiditic mudstones and anoxic hemipelagites contain just two ichno‐species, namely Chondrites ichnosp. and Planolites montanus both of which are common, albeit less so in the latter facies. The effects of preservation potential, medium and preservation mechanisms are also important controls on distribution.     

Commentary

Recently rediscovered type material referred to Muensteria Stern‐berg confirms that in its original (paleobotanical) definition this genus is too heterogenous to be useful in ichnotaxonomy. It contains plant remains, a coprolite string, and trace fossils. Some corrections concerning appearance of the analyzed specimens are introduced.     

Paleoecology of a large Early Cambrian bioturbator

The Lower Cambrian Poleta Formation in the White-Inyo Mountains of eastern California contains well-preserved and laterally extensive exposures of the large looping and meandering trace fossil Taphrhelminthopsis nelsoni n.isp. Such traces are typical features on upper bed surfaces of Lower Cambrian shallow marine sandstones and occur with Ediacaran fossils at other localities. Morphologic, sedimentologic and goniogram analyses suggest that the inferred tracemaker was a large soft-bodied echinozoan- or mollusc-grade animal with a volume greater than 14 cm³ that actively grazed or ingested sediment at the sediment-water interface. Although portions of these traces appear to reflect relatively 'complex' behavior, looping patterns are not periodic as expected for a systematic foraging strategy. T. nelsoni traces are patchy in distribution and commonly associated with suspect-microbial features, suggesting that tracemakers may have been targeting microbial-based or related concentrations of food resources. Such behavioral patterns are typical of shallow late Neoproterozoic-early Cambrian settings, and like suspect-microbial structures are later restricted to deep marine or stressed settings.     

Development and characterization of microsatellites from Senegal sole (Solea senegalensis)

To assist in the domestication of the sole fish Solea senegalensis, 15 microsatellites were developed from its genome (13 di‐ and two trinucleotide). These loci, along with three from S. solea that cross‐amplified, were characterized on a sample of 20 individuals of S. senegalensis from a hatchery stock. All loci were polymorphic displaying from two to 15 alleles/locus (mean 6.5). The results obtained from the hatchery population screening indicate that they might be useful for studies of genetic structuring and/or kinship analysis in S. senegalensis.     

Swimming trace of a coelacanth fish from the Lower Keuper of south-west Germany

Parundichna schoelli igen. nov., isp. nov. from the Middle Triassic (Ladinian) Lower Keuper of Rot am See (Baden-Württemberg, Germany) consists of clusters of sigmoidal scratches symmetrically arranged in a plaited pattern. It is here interpreted as the swimming trace of a large coelacanth fish. In contrast to ichnospecies of Undichna there is no unpaired groove left by the tail fin. Instead, the sets of parallel scratches resulted from the pendulum motion of two pairs of appendages, the pectoral and pelvic fins, which acted in alternation, as in tetrapods. This strange mode of swimming is compared to films of modern Latimeria and to computer simulations; it probably corresponds to a particular foraging behaviour. The presence of fittingly-sized coelacanths is documented in coeval carbonates (Alberti-Bank) by disarticulated skeletal elements. Since the Lower Keuper represents a fluvial and estuarine facies of the receding Muschelkalk sea, we cannot be sure whether this trace was made in a marine or freshwater environment.     

Gyrophyllites cristinae isp. nov. from Lower Ordovician Shallow-Marine Deposits of Northwest Argentina

Abstract

The lower Paleozoic marine siliciclastic succession of the Central Andean Basin, northwestern Argentina, provides a valuable record of the onset of the Great Ordovician Biodiversification Event in western Gondwana. A new ichnospecies of rosette trace fossil, Gyrophyllites cristinae, is documented from lower and upper Tremadocian (Tr1 and Tr2) deposits of this basin. It is characterized by five to six non-overlapping petaloid lobes and can be easily differentiated from the other four formally defined ichnospecies. Gyrophyllites cristinae occurs at the top of hummocky cross-stratified sandstone regularly interbedded with mudstone. These deposits are interpreted as reflecting the alternation of high-energy storm events and low-energy fair-weather conditions immediately below the fair-weather wave base, representing deposition in offshore transition environments. Gyrophyllites has been traditionally interpreted as the product of worms of uncertain taxonomic affinity that mined the sediment in search for food (fodinichnia). The occurrence of Gyrophyllites cristinae in these Ordovician deposits records post-storm colonization. Storms may have increased oxygenation and supplied fresh organic detritus that were exploited by worm-like, surface detritus- or shallow deposit-feeders exploring the uppermost silt-rich fine-grained sediments.     

Isolation and characterization of polymorphic microsatellite DNA markers in the brown sole,Pleuronectes herzensteini

New microsatellite DNA markers from brown sole were developed and characterized. Fourteen primer sets were designed from 40 microsatellite regions. Eight of 14 loci exhibited variations comprising 8–31 alleles. Observed and expected heterozygosities ranged from 0.611 to 0.833 and from 0.647 to 0.968 among 36 individuals, respectively. Phz3, Phz8 and Phz12 significantly deviated from Hardy–Weinberg equilibrium, and there was a significant linkage disequilibrium between Phz2 and Phz12. Seven of eight loci conformed to the Mendelian manner of inheritance in a full‐sib family. Seven to four loci of three related species were cross‐amplified by primers for brown sole.     

Names for trace fossils: a uniform approach

The taxonomic treatment of trace fossils needs a uniform approach, independent of the ethologic groups concerned. To this aim, trace fossils are rigorously defined with regard to biological taxa and physical sedimentary structures. Potential ichnotaxobases are evaluated, with morphology resulting as the most important criterion. For trace fossils related to bioerosion and herbivory, substrate plays a key role, as well as composition for coprolites. Size, producer, age, facies and preservation are rejected as ichnotaxobases. Separate names for undertracks and other poorly preserved material should gradually be replaced by ichnotaxa based on well-preserved specimens. Recent traces may be identified using established trace fossil taxa but new names can only be based on fossil material, even if the distinction between recent and fossil may frequently remain arbitrary. It is stressed that ichnotaxa must not be incorporated into biological taxa in systematics. Composite trace fossil structures (complex structures made by the combined activity of two or more species) have no ichnotaxonomic standing but compound traces (complex structures made by one individual tracemaker) may be named separately under certain provisions. The following emendations are proposed to the International Code of Zoological Nomenclature: The term 'work of an animal' should be deleted from the code, and ichnotaxa should be based solely on trace fossils as defined herein.     

An ethological framework for animal bioerosion trace fossils upon mineral substrates with proposal of a new class, fixichnia

Animal bioerosion trace fossils upon mineral substrates are analyzed from the point of view of the Seilacherian ethological classification. Several of the currently accepted ethological classes: cubichnia, fugichnia, repichnia, fodinichnia, agrichnia, calichnia and aedificichnia are not represented in these substrates. This fact points out a lower behavioral diversity of hard substrate trace fossils when compared with soft sediment trace fossils. Bioerosion traces can be classified in just five classes: domichnia, pascichnia, equilibrichnia, praedichnia and fixichnia. Fixichnia is here erected to gather superficial etching scars resulting from the anchoring of fixation of sessile epiliths by means of a soft or skeletal body part. Praedichnia and fixichnia are exclusive of the bioerosion realm.     

Isolation and characterization of polymorphic microsatellites for the bastard sole (Microchirus azevia)

The bastard sole (Microchirus azevia) is a species of commercial interest in Spain. Nevertheless, little information is currently available about the genetic characteristics of wild populations. In this survey, we have developed eight new microsatellites using an enriched genome library protocol. Primers were screened on a total of 54 individuals from two wild populations (Mediterranean and Atlantic) from the south coast of Spain, revealing six to 18 alleles per locus with expected heterozygosities ranging from 0.51 to 0.94. These markers can potentially be useful tools for use in population genetic studies.     

The dispersion of sole, Solea solea and plaice, Plemonectes platessa within and away from a nursery ground in the Irish Sea

Populations of sole and plaice were sampled on and around a nursery on the North Wales coast during May, July arid October 1989 and 1990, and the distribution of age-groups described. Pre-recruit sole were tagged and reieased on the same area during September 1988 to provide information on their larger scale movements. Juvenile sole remained on the nursery ground close inshore until after their first winter, whereas plaice of the same age—group became more widely dispersed. Both species were still associated with the coastal zone as 2-groups, when they were vulnerable to capture by commercial trawls. The gradual movement of sole out of the nursery was almost complete by October of their third year. Sole tag returns were obtained mainly from the NE Irish Sea. and also from the E coast of Ireland. Only three of the 68 returns came from outside the Irish Sea, one from the SE Irish coast, one from Swansea Bay and another from the outer Bristol Channel. Published data indicated that plaice undergo more rapid and more extensive migrations within and away from the Irish Sea than sole of the same age-group. Juvenile plaice and sole populations from nursery grounds throughout the NE Irish Sea would become mixed, and could contribute to any of the spawning populations in that area.     

Vagorichnus,a new ichnogenus for feeding burrow systems and its occurrence as discrete and compound ichnotaxa in Jurassic lacustrine turbidites of Central China

A new ichnogenus, Vagorichnus, is figured and described from Jurassic lacustrine turbidites of the Anyao Formation, Henan Province, Central China. Vagorichnus consists of complex burrow systems composed of discontinuous curved to meandering segments in which irregular networks are formed. The ichnospecies V. anyao covers burrow systems characterized by constricted and irregularly annulated segments, and ridge‐like knobs. Although traces are preserved as hypichnial ridges on the sole of turbidite sandstones, several lines of evidence indicate that these ichnofossils record the activity of a post‐event infauna. Vagorichnus occurs as discrete and compound ichnotaxa. In the latter case, it grades into Gordia and Tuberculichnus. Vagorichnus is interpreted as invertebrate feeding structures (Fodinichnia).     

Isolation of polymorphic DNA microsatellites in the common sole Solea vulgaris

A microsatellite‐enriched genomic library was obtained from the common sole, Solea vulgaris, and seven polymorphic dinucleotide markers were successfully optimized. These markers showed levels of expected heterozygosity ranging from 0.55 to 0.83 and allele number ranging from eight to 12. Three of these markers were also found to successfully amplify in the closely related Solea senegalensis and can be employed to define population genetic structure of the two Solea species and for inferring stock origins.     

Borings in trepostome bryozoans from the Ordovician of Estonia: two ichnogenera produced by a single maker, a case of host morphology control

The evolution of borings has shown that the morphology of borings is a function of both the borer and its substrate. This study investigated the effect of bryozoan internal skeletal morphology on the dimensions and distribution of borings. One hundred and forty-three trepostome colonies from the Middle and Upper Ordovician strata of northern Estonia were examined. Of these, 80% were matrix entombed, longitudinally sectioned ramose and hemispherical colonies, and 20% were matrix-free hemispherical colonies that allowed examination of the colony surfaces. Seventy-one percent of the ramose colonies were bored, whereas 88% of the hemispherical colonies were bored. On average, only 8% of colony surface areas were bored out. Borings were more randomly oriented in the hemispherical colonies. In contrast in the ramose colonies, the borings tended to more restricted to the thin-walled endozone and thus parallel to the branch axis. This is interpreted to be a function of the thick-walled exozones controlling to some extent where the borer could bore. Based on morphology, the borings in the hemispherical colonies are referred to Trypanites and those in the ramose colonies to Sanctum . Sanctum is revised to include two possible openings and to recognize that boring shapes were inherently constrained by the thick-walled exozones of the host bryozoan colonies. Both trace fossils were probably produced by a boring polychaete that used the tubes as domiciles.     

Isolation and characterization of ten microsatellite loci for Senegal sole (Solea senegalensis Kaup)

Senegal sole (Solea senegalensis Kaup) is a high‐value marine flatfish exploited in both fisheries and aquaculture. Here we describe the isolation of seven tetranucleotide and three dinucleotide polymorphic microsatellite loci. Characteristics of a captive broodstock and a wild population are described. Three loci displayed a significant departure from Hardy–Weinberg expectations in both populations, suggesting a substantial frequency of null alleles. The remaining seven loci were found to be in equilibrium in the wild population, whereas only four of them were in the cultured population. Cross‐species amplification was successful for three loci in other five flatfishes.