Trilobites

This study examines the geological features of the Southern Nopah Range at Emigrant Pass, California, with a focus on stratigraphy, lithology, and structural geology. Field methods included lithological mapping, measurement of bedding orientations, and fault system documentation. Results indicate that the area is an extensional province characteristic of the Basin and Range tectonic regime. Observations reveal rift-bound normal faults and variations in rock units and stratigraphic sequences, which chronicle a history of deposition, uplift, and deformation. These findings contribute to understanding the tectonic evolution and sedimentation processes within this dynamic extensional setting, offering insights into the interplay between marine deposition and structural deformation in the region's geological history.

Glacial erratics belonging to the Rickard Hill facies (RHf) of the Saugerties Member of the Schoharie Formation (upper Emsian: Lower Devonian) occur scattered throughout the Piedmont of northern New Jersey and Lower Hudson Valley of New York. These RHf glacial erratics contain an assemblage of trilobites belonging to: Anchiopella anchiops, Burtonops cristatus, Calymene platys, Terataspis grandis, cf. Trypaulites sp. and cf. Coniproetus sp. This RHf glacial erratic trilobite assemblage consists predominantly of disarticulated cephala and pygidia that were originally preserved as part of a localized, third-order eustatic sea level lag deposit in the area of the present day Helderberg Mountains region of New York State and subsequently transported in glacially plucked blocks by the Hudson-Champlain Lobe of the Laurentide Ice Sheet southward into New Jersey. Physical and chemical weathering during glacial erosion, transportation and deposition of the RHf glacial erratics has revealed some anatomical features of these trilobites in high detail along with other invertebrates. This unique sequence of weathering reveals additional characteristics that bear upon issues of bathymetric controls on upper Schoharie Formation lithology, trilobite faunal abundance and taphonomy during the upper Emsian (Lower Devonian) of eastern New York State. RÉSUMÉ Des éléments erratiques glaciaires faisant partie du faciès de la Rickard Hill (RHf) du Membre Saugerties de la Formation de Schoharie (Emsien supérieur: Dévonien inférieur) sont présents de façon éparse partout à l'intérieur du Piedmont dans le nord du New Jersey et la vallée du cours inférieur de l'Hudson de l'État de New York. Ces éléments renferment un assemblage de trilobites faisant partie des Anchiopella anchiops, Burtonops cristatus, Calymene platys et Terataspis grandis, comparables à l' espèce des Trypaulites et à l' espèce des Coniproetus. Cet assemblage de trilobites des éléments erratiques glaciaires du RHf est principalement constitué de céphalums et de pygidiums ayant originalement été conservés au sein d'une charge de fond localisée, au niveau marin eustatique de troisième ordre, dans le secteur de la région des monts Helderberg actuels de l'État de New York et subséquemment transportés dans des blocs grainelés par l'impact glaciaire du compartiment Hudson-Champlain de l'Inlandsis laurentidien en direction sud vers le New Jersey. L'altération atmosphérique physique et chimique survenue durant l' érosion glaciaire, le transport et la sédimentation des éléments erratiques glaciaires du RHf ont révélé certaines particularités anatomiques des trilobites de façon très détaillée ainsi que d'autres invertébrés. Cette séquence unique d'altération atmosphérique révèle d'autres caractéristiques témoignant d'un contrôle bathymétrique sur la lithologie

Through his numerous papers, articles, some books and lectures, a prolific palaeontologist Rudolf J. Prokop (Department of Palaeontology, National Museum, Praha) has become known in our country and abroad as one of the best European echinoderm specialists of our time. His special interest over the years has been the echinoderm fauna of the Bohemian Lower Palaeozoic. A brief biography and bibliography of him is to be found in two articles by V. Petr in the 1994 issue of this journal and in the 1994 issue of Český kras. Herein, a list of fossil invertebrates bearing the name of Rudolf Prokop is presented for the first time and updated addition to his bibliography is also included.

Formal subdivision of the Cambrian System into four series and ten stages is in progress. The base of Cambrian Stage 3 (provisional), which is conterminous with the base of Cambrian Series 2 (provisional), is expected to be placed at a horizon close to the first appearance of trilobites, which marks the onset of the largest phase of the Cambrian explosion. Conceptually, an ideal boundary position would be marked by a significant and globally recognizable bioevent that divides the lower part of the Cambrian System into a sub-trilobitic Terreneuvian Series and a trilobite-dominated Series 2. If the level is to be identified principally through biostratigraphic means, its position also needs to be recognizable using non-biostratigraphic means, and its correlation potential should be tested through detailed investigation of several continuous successions embracing the critical interval. Major difficulties in identifying a suitable horizon include strong biotic provincialism, a plethora of regional unconformities, and facies changes on different paleocontinents in the Cambrian Terreneuvian-Series 2 boundary interval. Levels that provide potential for intercontinental correlation include the first appearance position of trilobites and the approximately equivalent first appearance positions of certain small shelly fossil and acritarch species. In addition, a non-biostratigraphic marker, such as a stable carbon isotopic excursion, may be useful as a correlation level. Cambrian Series 2 and Stage 3 are provisional stratigraphic units, and their conterminous base was previously suggested to coincide to the appearance of trilobites. Compared to other potential chronostratigraphic indicators, the first appearance of trilobites still has advantages for recognizing and correlating the base of Stage 3, and should remain as the provisional primary marker for the boundary position.

Formal subdivision of the Cambrian System into four series and ten stages is in progress. The base of Cambrian Stage 3 (provisional), which is conterminous with the base of Cambrian Series 2 (provisional), is expected to be placed at a horizon close to the first appearance of trilobites, which marks the onset of the largest phase of the Cambrian explosion. Conceptually, an ideal boundary position would be marked by a significant and globally recognizable bioevent that divides the lower part of the Cambrian System into a sub-trilobitic Terreneuvian Series and a trilobite-dominated Series 2. If the level is to be identified principally through biostratigraphic means, its position also needs to be recognizable using non-biostratigraphic means, and its correlation potential should be tested through detailed investigation of several continuous successions embracing the critical interval. Major difficulties in identifying a suitable horizon include strong biotic provincialism, a plethora of regional unconformities, and facies changes on different paleocontinents in the Cambrian Terreneuvian-Series 2 boundary interval. Levels that provide potential for intercontinental correlation include the first appearance position of trilobites and the approximately equivalent first appearance positions of certain small shelly fossil and acritarch species. In addition, a non-biostratigraphic marker, such as a stable carbon isotopic excursion, may be useful as a correlation level. Cambrian Series 2 and Stage 3 are provisional stratigraphic units, and their conterminous base was previously suggested to coincide to the appearance of trilobites. Compared to other potential chronostratigraphic indicators, the first appearance of trilobites still has advantages for recognizing and correlating the base of Stage 3, and should remain as the provisional primary marker for the boundary position.

With 9 figures K u r z f a s s u n g: Im vorliegenden Artikel wird der derzeitige Kenntnisstand fiber die unterkambri-schen Trilobitenfaunen der Gegend um G6rlitz (Sachsen) mitgeteilt. Zus~itzlich zu den seit langem bekannten Arten werden Calodiscus cf. lobatus und Ferralsia saxonica n. sp. aus den untersuchten Schichten vorgestellt. Die Olenelloiden, die bisher als zwei eigensfiindige Arten angesehen wurden, werden als identische Art interpretiert. Lusatiops bederkei wird nut durch verformte Stficke von L. lusaticus repriisentiert. Die stratigraphische Aussagekraft der Trilobiten und Probleme, die aufgrund der biostratigraphischen Daten auftreten, sowie die Korrelationen der Abfolgen werden diskutiert. Abstract: The present article reviews recent advances in the knowledge of the Lower Cambrian trilobite faunas of the G6rlitz area, Saxonia, eastern Germany. New additions to the fauna are Calodiscus of. lobatus (HAL~.) and Ferralsia saxonica n. sp. The olenelloid trilobites, previous...

Formal subdivision of the Cambrian System into four series and ten stages is in progress. The base of Cambrian Stage 3 (provisional), which is conterminous with the base of Cambrian Series 2 (provisional), is expected to be placed at a horizon close to the first appearance of trilobites, which marks the onset of the largest phase of the Cambrian explosion. Conceptually, an ideal boundary position would be marked by a significant and globally recognizable bioevent that divides the lower part of the Cambrian System into a sub-trilobitic Terreneuvian Series and a trilobite-dominated Series 2. If the level is to be identified principally through biostratigraphic means, its position also needs to be recognizable using non-biostratigraphic means, and its correlation potential should be tested through detailed investigation of several continuous successions embracing the critical interval. Major difficulties in identifying a suitable horizon include strong biotic provincialism, a plethora of regional unconformities, and facies changes on different paleocontinents in the Cambrian Terreneuvian-Series 2 boundary interval. Levels that provide potential for intercontinental correlation include the first appearance position of trilobites and the approximately equivalent first appearance positions of certain small shelly fossil and acritarch species. In addition, a non-biostratigraphic marker, such as a stable carbon isotopic excursion, may be useful as a correlation level. Cambrian Series 2 and Stage 3 are provisional stratigraphic units, and their conterminous base was previously suggested to coincide to the appearance of trilobites. Compared to other potential chronostratigraphic indicators, the first appearance of trilobites still has advantages for recognizing and correlating the base of Stage 3, and should remain as the provisional primary marker for the boundary position.

Diversos sills subvolcanicos. aflorantes en el área de Arándiga-(Zaragoza) se emplazan en sedimentos pertenecientes al transito del Keuper al Rhetiense-Hettangiense. Corresponden a basaltos alcalinos cuyos minerales primarios (olivino, piroxeno, plagioclasa) se han transformado en albita-oligoclasa, ortosa, clorita, clorita-esmectita, carbonatos, etc. Es característica de 10s sills una zonaci6n petrográfica reconocible en sus propiedades texturales y asociaciones minerales. La composici6n química de estas rocas ha experimentado asimismo importantes modificaciones. Las pautas de variación de 10s elementos incompatibles indican una pequeiia diferenciación magmiítica. Tiene notable afinidad con rocas, de an6loga composi-ci6n y edad, aflorantes en..otros sectores de la Cadena Ibérica. Según ha sido expuesto por diversos autores, representa una provincia alcalina que, con edad Trias-Lias, esta asociado a un rifting intracontinental que afecta al borde occidental del Tethys.

espanolEl analisis de polen, diatomeas y foraminiferos de un sedimento litoral en la Ria de Ares (A Coruna, Espana) ha permitido interpretaciones paleoambientales comparables. Se trata de un sedimento turboso con macrorrestos vegetales. El analisis micropaleontologico de este nivel y las dataciones absolutas situan la formacion del mismo en el periodo Subboreal. La lectura paleoecologica obtenida a traves del estudio micropaleontologico nos permite reconstituir dos paleoambientes fundamentalmente: un medio continental vegetado y un ambiente con condiciones salobres, consecuencia del aumento del nivel del mar. EnglishPollen, diatoms and foraminifera from a raised marine sediment of the Ria de Ares (A Coruna, Spain) area produced comparable paleoenvironmental interpretations. It is an organic formation with peat associated with numerous vegetal rests. The micropaleontological analysis of this level and the absolute dating, place its formation in the Subboreal period. The paleoecologic...

discovered just such a polymorphism on chromosome 4, which is linked to Huntington's disease, after screening with only three probes. That this led to the identification of the genetic disease locus made linkage analysis seem relatively easy and highly effective. But the hunt for mood genes has so far proved to be a dismal failure. Claims made for linkages to the X chromosome and chromosomes 11 and 18, based on studies of Amish, Israeli and Costa Rican pedigrees respectively, have not been substantiated. Frustrated, Barondes turns to Alzheimer's disease, susceptibility to which is increased by the presence of the apolipoprotein A4 genotype, to reassure us that gene linkage can be useful in studying mental disorders. Because the linkage approach has failed to identify mood genes, the peremptory dismissal of the candidate gene approach is puzzling. However, this and other inconsistencies do not detract from the overall importance of Mood Genes as an interim account of an exciting gene hunt, written in comfortable and in parts racy prose by an authority in the field. The evidence for the genetic transmission of mood disorders is incontrovertible, so the hunt must go on.

Se presenta el estudio lito y bioestratigráfico de la Formación Pizarras del Sueve en su area tipo de la Zona Cantábrica oriental, a partir de! análisis de nueve perfiles estratigráficos fosilíferos, enclavaclos en sus afloramientos más septentrionales. Estos han posibilitado definir formalrnente la unidacl, constituida esencialrnente por pizarras negras (Miernbros Cerracín y Cofiño), en cuya base pueclen aparecer horizontes de hierro oolítico, separados por un trarno medio de areniscas y pizarras (Miembro Bayo). que alcanzan en conjunto 50-100 m de potencia. El contenido paleontológico es muy notable, identificándose medio centenar de especies de invertebrados marinas (graptolitos, trilobites, ostrácoclos, braquiópodos. rnoluscos, equinodermos) e icnofósiles, a los que se suman de modo preliminar otras setenta especies de microfósiles de pared organica (quitinozoos y acritarcos). Estes últirnos, junto con los graptolitos, aportan informaciones bioestratigraficas muy precisas para l...

The first Furongian trilobites are described herein from the Cambrian of the Cantabrian Zone, NW Spain. They were collected during the construction of the "Túnel Ordovícico del Fabar" from the shales of "El Fabar Beds" in the La Matosa member of the Barrios Formation. The assemblage includes the aphelaspidine genus Maladioidella, with a specimen identified as M. cf. colcheni, a species previously known from Sierra de la Demanda (Spain), and possibly Sardinia and Oman. Fragments of an indeterminate olenid trilobite and phyllocarid crustaceans have also been recorded. Based on the acritarch assemblage, these beds are considered as late Jiangshanian or earliest Stage 10 of the Cambrian System. The ichnofossil Cruziana semiplicata has also been collected in the tunnel from the upper part of the Ligüeria Member (Tremadocian) of the Barrios Formation, clearly postdating the occurrence of Maladioidella colcheni, its supposed tracemarker according to some authors. The separate record of both taxa (a Furongian trilobite and a Cambro-Ordovician trace fossil) does not support this statement, so their relationship would be refuted in this case. • Key words: Cambrian, Furongian, trilobites, trace fossils, Cantabrian Zone, Spain.

Los graptolitos silúricos de la Zona Centroibérica suelen conservarse aplastados en pizarras negras, pero en algunos yacimientos los rabdosomas pueden retener parte de su relieve original o conservarse incluso en tres dimensiones. La mayoría de las veces existe una piritización temprana de los rabdosomas por la acción de bacterias sulforreductoras en ambiente anóxico, a la que se suma la génesis de nódulos. La alteración posterior de la pirita deja los graptolitos en forma de moldes, que pueden ser estudiados mediante vaciados en látex. Otros fenómenos de piritización multifásica en sedimentos gruesos conducen a la formación de nódulos de pirita que incluyen en su interior graptolitos huecos y en tres dimensiones, con el peridermo replicado delicadamente en óxidos de hierro. En otras ocasiones, los graptolitos preservados en nódulos generados en sedimentos pelágicos incluyen el recrecimiento de fosfatos sobre el peridermo de los graptolitos, que llegan a conservarse huecos y con estructuras de rellenos geopetales. Finalmente, se presenta el único caso de calizas con graptolitos conocido en el Silúrico centroibérico.

Modularity of the cranidium of Crassifimbra? metalaspis, a Cambrian ptychoparioid trilobite, is investigated using landmark-based geometric morphometric methods to gain insight into the integration among morphogenetic processes responsible for shaping the head of an ancient arthropod. Of particular interest is the extent to which the structure of phenotypic integration was governed by direct interactions among developmental pathways, because these interactions may generate long-term constraints on evolutionary innovation. A modified two-way ANOVA decomposes cranidial shape variation into components representing symmetric variation among individuals and fluctuating asymmetry (FA). The structure of integration of each of these components is inferred from correlated deviations in shape among nine partitions of the cranidium. Significant correlation among partitions in FA indicates direct interactions among their respective developmental pathways. An a priori hypothesis that modularity was determined by functional association among partitions is not well supported by the among-partition correlation structure for either component of variation. Instead, exploratory analyses reveal that phenotypic integration was strongly influenced by spatially localized morphogenetic controls. Comparison of the structures of the Individuals and FA components of variation reveals that the two share relatively few commonalities: the structure of phenotypic integration was only weakly influenced by direct interactions. The large contribution of parallel variation to phenotypic integration suggests that modularity was unlikely to have imposed a long-term constraint on evolutionary innovation in these early trilobites.

Modularity of the cranidium of Crassifimbra? metalaspis, a Cambrian ptychoparioid trilobite, is investigated using landmark-based geometric morphometric methods to gain insight into the integration among morphogenetic processes responsible for shaping the head of an ancient arthropod. Of particular interest is the extent to which the structure of phenotypic integration was governed by direct interactions among developmental pathways, because these interactions may generate long-term constraints on evolutionary innovation. A modified two-way ANOVA decomposes cranidial shape variation into components representing symmetric variation among individuals and fluctuating asymmetry (FA). The structure of integration of each of these components is inferred from correlated deviations in shape among nine partitions of the cranidium. Significant correlation among partitions in FA indicates direct interactions among their respective developmental pathways. An a priori hypothesis that modularity was determined by functional association among partitions is not well supported by the among-partition correlation structure for either component of variation. Instead, exploratory analyses reveal that phenotypic integration was strongly influenced by spatially localized morphogenetic controls. Comparison of the structures of the Individuals and FA components of variation reveals that the two share relatively few commonalities: the structure of phenotypic integration was only weakly influenced by direct interactions. The large contribution of parallel variation to phenotypic integration suggests that modularity was unlikely to have imposed a long-term constraint on evolutionary innovation in these early trilobites.

The area included in the Amberloup-La Roche-en-Ardenne-Houffalize sector is located in the province of Luxembourg and belongs geographically to the Central Ardenne. The rocks are of Lower Devonian age. On the regional level, the region integrates southeast of the axial zone of the Ardenne Anticlinorium, northwest of the Neufchâteau Synclinorium. Geological mapping at the scale of 1 : 10 000 has identified numerous faults ignored on old geological maps at a scale of 1 : 40 000. The greater part of map-sheet Houffalize is modeled by the Houffalize Syncline, which extends into the lower third of map-sheet Wibrin. The detailed surveys of its northern flank and the transition zone to the La Roche Syncline in the northwest show that the intermediate structure does not correspond to a simple anticline known in the literature as Taverneux Anticline. During the Variscan orogeny, an anticline was effectively formed, then it overturned north and, finally, was segmented by longitudinal faults which, initially, were reverse faults, but some were reactivated as normal faults during a phase of relaxation.

A construção do verdadeiro parece então como um proieto h¡storico abeño; é uma construção humana, tendo aliás um caráter estético, na medida em que o espírito humano nela se encontra. (.../ Esse caráter h¡storico não implica gue se possa construir, de maneira equivalente, qualquer verdade: sabemos que as representações teóricas não são todas bem suced¡das. Na construção histórica do verdadeiro, por exemplo, encontramos uma dimensão que não dominamos e não consegu¡mos seguer descrevêJa inteiramente. Em filosofia, desrgrna-se por meio de diversos ferrnos esse limite em que o ser humano sente que ele não é tudo. (Fourez, 1988, p. 255) i Este trabalho é dedicado: l) À fan¡a e ao pequeno Gabriet, : constantes e amados : companhe¡ros. , Aos meus pais, Mar¡a e Abílio, I refe rê n c i a s essenciars. AGRADECIMENTOS Este trabalho contou com a colaboração de diversas pessoas e instituições. Ao Prof. Dr. Setembr¡no Petr¡ (|G/USP), sou grato pelo aceite na orientação desta pesquisa e pelas inúmeras sugestões e crít¡cas oferecidas no decorrer deste período, o que tornou esta caminhada menos angustiante. A sua experiência e segurança foram fundamentais como exemplo de conduta profissional. À Prof Dra Maria Antonieta Rodrigues (FGEUUERJ), sou imensamente grato pelo apoio, incentivo e facilidades logísticas oferecidas por meio da concessão, através do projeto PADCT/FINEP no 65.91.0373.00, por ela coordenado, de verbas para a realização de trabalhos de campo, análises laboratoriais e despesas fotográficas, que viabil¡zaram a realizaçáo desta pesquisa. A amplitude de espirito da ProF Antonieta, seu humanismo e seus conhecimentos vêm permitindo a estruturação e a manutençåo do entrosamento da equipe de pesquisa do "'Paleozóico da Bacia do Paraná" por um longo período. O convívio em me¡o a este grupo de pesquisa foi fundamental para a elaboração e desenvolvimento do trabalho aqui apresentado. Minha concepção a respeito da estratigrafia da seção pré-carbonífera foi construída, em sucessivas etapas de campo, em diferentes domínios da bacia, conjuntamente com o amigo e colega de trabalho Prof. Egberto Pereira (FGEUUERJ). Ao Egberto, sou grato também pelas incontáveis sugestões e criticas feitas nesses anos. Às Profa' Nina Paula Laranjeira (UnB) e Sandra de Fátima Oliveira (UFG, Goiânia)' sou grato pelo convívio amigo mantido desde 1992, pela colaboração nas etapas de campo e pelas proveitosas discussões e sugestóes mantidas em nossos encontros. Ao Geó|, José Henrique G. de Melo (Cenpes/PETROBRAS), grande referência de competência e dedicação entre os pesquisadores da geologia sedimentar paleozóica, sou grato pelas inúmeras discussões, sugestões e esclarecimentos acerca dos aspectos bioestratigráficos e paleogeográficos do Devoniano da bacia. Muitas de minhas concepções relacionadas à caßcledzaçâo de sistemas deposicionais do Devoniano lnferior da bacia foram fortemente influenciadas por constantes e instigantes discussöes com o amigo Prof. Leonardo Borghi (|G-UFRJ). Sou também grato ao Leonardo pelo convívio, marcado por estimulantes discussóes de temas sempre controversos que caracterizam nosso trabalho. tv Ao prof. Dr. Renê Rodrigues (PETROBRAS e FGEUUERJ), sou grato pela inestimável colaboraçäo e orientação no desenvolvimento das análises geoquímicas, como também pelos estímulos e críticas feitas nos últimos anos. Ao prof. Dr, Rodolfo Dino (PETROBRÁS e FGEUUERJ), sou grato pelas discussöes acerca dos aspectos bioestratigráficos do Devoniano da bacia e pelas diversas sugestöes apresentadas no decorrer dos trabalhos. Aos colegas professores Dr. Yngve Grahn e Dr. Antônio carlos sequeira Fernandes' da FGEUUERJ, sou grato pelas discussões e informações relacionadas' respectivamente' à bioestrat¡grafia e à icnologia do pré-Carbonífero da bacia. Aos professores D¡. Thomaz R. Fairchild e Dr. Paulo c.F. Gianinni, do lG-usP, sou grato pelas críticas e sugestões encaminhadas na defesa do exame de qualificação' Aos professores Dr. Jorge Della Fávera e Dr. Hernan¡ chaves, da FGEUUERJ, sou grato pelas positivas influências exercidas no campo da ética da Eskatigrafia 'moderna', em especial na colaboração da compreensåo da dinåmica de sedimentação e de preservação do registro em bacia intracratônica.

A low‐diversity graptolite fauna from the upper part of the Eusebio Ayala Formation exposed in the intracratonic Paraná Basin of eastern Paraguay is reported herein. The sections studied are composed dominantly of red micaceous mudstones with intercalations of purple sandstones from a series of clay quarries (Santa Elena; Galeano; Western Itauguá) around Itauguá city. The graptolites Metaclimacograptus sp., Normalograptus cf. ajjeri (Legrand), and Normalograptus cf. medius (Törnquist) indicate an early Llandovery age for the upper Eusebio Ayala unit. Compared to coeval, postglacial successions in southwestern Gondwana, the graptolites studied have their closest affinities with those from the Rhuddanian lower Lipeón (Subandean Ranges, northwestern Argentina) and La Chilca (Precordillera) formations. In addition, a trilobite assemblage dominated by the genus Mucronaspis was collected from the Eusebio Ayala Formation type locality near Eusebio Ayala city. The latter represents an isola...

This dissertation contains 19 research papers published since 1967, relating primarily to the functional organisation of trilobites, and to the taxonomy of some Ordovician and Silurian trilobite faunas. These papers are preceded by a., short summary in which the aims, methods and conclusions of this work are briefly explained. The bulk of the functional work is concerned with the eyes of trilobites-the oldest known visual system. Little was known about these eyes beforehand, but the long geological record and often good preservation has enabled many details of their structure, evolution and function to be clarified. It was initially confirmed, that there were two types of eye, 1981 E.N.K. Clarkson and Yvonne Howells. Upper Llandovery trilobites from the Pentland Hills, near Edinburgh, Scotland. Palaeontology vol. 24, 507-536. 1982 E.N.K. Clarkson and R.P. Tripp. The Ordovician trilobite Calyptaulax brongniartii. Trans. Roy. Soc. Edin. Earth Sciences 72, 287-294.

The illaenid trilobite Vysocania is widely represented in the Upper Ordovician of the Czech Republic, Portugal and Spain, and is one of the most characteristic taxa in the high-latitude peri-Gondwana palaeobiogeographical region to which it is endemic. Three species of the genus that were formerly assigned to Stenopareia and Zetillaenus, from the Czech Republic and Spain respectively, are herein revised, and a new species is described from the Czech Republic. The genus Octillaenus, of which a new species is described from the Upper Ordovician of Morocco, is considered to have arisen from Vysocania through paedomorphic (neotenic) processes. The relationships between Vysocania, Octillaenus, Stenopareia and Zetillaenus are reviewed and the criteria used in the definition of these taxa discussed. Species assigned to Vysocania are V. vaneki (type-species), V. iberica, V. moraveci sp. nov. and V. panderi; species assigned to Octillaenus are O. hisingeri (type-species) and O. marocanus sp. nov. Vysocania appears for the first time in the lower Berounian (Sandbian) and has its last undoubted record in the upper Berounian (upper Katian); Octillaenus is presently restricted to the Kralodvorian (upper Katian). • Key words: Stenopareia, Zetillaenus, Illaenidae, high-latitude peri-Gondwana, Dalmanitoidean Realm.

To a large extent, a chitinous external cuticle is the distinguishing feature of arthropods (Barnes, 1980). Many of the other features considered characteristic of arthropods, such as growth by molting or the jointed appendages, are either directly or indirectly tied to the possession of the cuticle (Cisne, 1974; Neville, 1975; Grasshoff, 1981).

Givetian limestones near Čelechovice contain rather abundant trilobites be longing to several species (for summary see Chlupáč 1992), whereas the Frasnian limestones of the Moravian Karst development are generally poor in trilobites and only a few rare specimens have been mentioned or described in the literature (

The Windermere Supergroup in southern British Columbia and its correlatives (such as the Pocatello Formation and lower Brigham Group in southeastern Idaho) along the western North American Cordilleran margin are an archetype of Neoproterozoic to early Paleozoic tectonic, sedimentary, and climatic processes. The central Idaho portion of the margin remains relatively understudied when compared to regions to the south in southeastern Idaho or to the north in northeastern Washington. This is in part a legacy of early workers, who identified the absence of Neoproterozoic and Cambrian strata in east-central Idaho across the Lemhi arch. However, Neoproterozoic and Cambrian rocks are indeed present west of the Lemhi arch within the central Idaho section of the Cordillera. Here, we summarize recent advances in our understanding of these strata within central Idaho and correlate the Pocatello Formation and Brigham Group rocks from northern Utah/southeastern Idaho through central Idaho to northeastern Washington. We also provide new constraints that link Cambrian strata from central Idaho across the Lemhi arch to southwestern Montana. Collectively, this emerging tectono-stratigraphic framework suggests extensive, some likely diachronous, stratigraphic boundaries and magmatic events relating to (1) widespread rifting ca. 720-680 Ma; (2) early and late Cryogenian (Sturtian and Marinoan) glacial sedimentation; (3) base-level drawdown and formation of incised valleys, previously correlated to the Marinoan glacial interval, but which now appear to be younger (ca. 600 Ma) and perhaps related to tectonic activity; (4) onset of the Sauk I transgression 560-530(?) Ma; (5) the ca. 515 Ma Sauk II lowstand, perhaps

We define the Sun Valley Group of south-central Idaho to include the Desmoinesian to Leonardian Wood River, Dollarhide, and Grand Prize Formations, which consist of 2000 to 3400 m of mixed carbonate-siliciclastic strata deposited in the epicratonic Wood River basin. In the Woo d River Formation we revise the basal Hailey Member to make it more easily mappable, and define overlying Eagle Creek and Wilson Creek Members. The Middle Pennsylvanian part of the Sun Valley Group contains proximallyderived conglomerate and interbedded biostromal limestone deposited on a braiddelta and adjacent slope. The Late Pennsylvanian to Early Permian part of the group comprises a south-sloping finegrained mixed carbonate-siliciclastic rampapron system. This system received cratonal quartz sand from a northern source and comminuted bioclastic debris and micrite from the coeval Snaky Canyon Formation to the east.

Recent fieldwork in the state of Mato Grosso made it possible to find new specimens of trilobites, among them: Metacryphaeus australis, Metacryphaeus sp., and a homalonotide. Taphonomically, it was possible to observe that there are two patterns of conservation, one of which is where the specimens are complete, related to a rapid burial event; and another pattern of preservation where paleoenvironmental conditions provided disarticulation after death. These new findings, as well as their taphonomic interpretations, open possibilities to work on biostratigraphic correlations, in addition to paleobiogeographic assessments for trilobites in South America.

Upper Ordovician-Lower Devonian rocks of the Cabrières klippes (southern Montagne Noire) and the Mouthoumet massif in southern France rest paraconformably or with angular discordance on Cambrian-Lower Ordovician strata. Neither Middle-Ordovician volcanism nor associated metamorphism is recorded, and the subsequent Middle Ordovician stratigraphic gap is related to the Sardic phase. Upper Ordovician sedimentation started in the rifting branches of Cabrières and Mouthoumet with deposition of basaltic lava flows and lahar deposits (Roque de Bandies and Villerouge formations) of continental tholeiite signature (CT), indicative of continental fracturing. The infill of both rifting branches followed with the onset of: (1) Katian (Ka1-Ka2) conglomerates and sandstones (Glauzy and Gascagne formations), which have yielded a new brachiopod assemblage representative of the Svobodaina havliceki Community; (2) Katian (Ka2-Ka4) limestones, marlstones and shales with carbonate nodules, reflecting development of bryozoan-echinoderm meadows with elements of the Nicolella Community (Gabian and Montjoi formations); and (3) the Hirnantian Marmairane Formation in the Mouthoumet massif that has yielded a rich and diverse fossil association representative of the pandemic Hirnantia Fauna. The sealing of the subaerial palaeorelief generated during the Sardic phase is related to Silurian and Early Devonian transgressions leading to onlapping patterns and the record of highangle discordances.

Later Cambrian and earliest Ordovician trilobites and brachiopods spanning eight horizons from five localities within the Sông Mã, Hàm Rồng and Đông Sơn formations of the Thanh Hóa province of Việt Nam, constrain the age and faunal affinities of rocks within the Sông Đà terrane, one of several suture/fault-bounded units situated between South China to the north and Indochina to the south. ‘Ghost-like’ preservation in dolomite coupled with tectonic deformation leaves many of the fossils poorly preserved, and poor exposure precludes collecting within continuously exposed stratigraphic successions. Cambrian carbonate facies pass conformably into Lower Ordovician carbonate-rich strata that also include minor siliciclastic facies, and the recovered fauna spans several uppermost Cambrian and Lower Ordovician biozones. The fauna is of equatorial Gondwanan affinity, and comparable to that from South China, North China, Sibumasu and Australia. A new species of Miaolingian ‘ptychopariid’ tril...

Imperfectly preserved specimen of a supposed hydrozoan Medusites cf. radiatus Linnars., originally described by Pompeckj (1896) from the "Pod trn ım" locality near T y rovice (Slapnice Member of the Buchava Formation, Skryje-T y rovice Basin) is revised. Recent study of the original specimen and a more complete topotype specimen testify the affiliation to the pineapple-shaped ichnogenus Astropolichnus (Crimes and Anderson, 1985). A new ichnospecies A. bohemicus is established on the material from the Buchava Formation. This material is the first occurrence of Astropolichnus in the middle Cambrian as well as the first report of this ichnogenus in the Barrandian area of Czech Republic.

Reçu le 26 mars 2003 ; révisé et accepté le 1 septembre 2003 Rédigé à l'invitation du Comité éditorial Résumé Les hétérochronies du développement sont définies comme des changements du « temps relatif d'apparition » et du « taux de développement » de caractères ancestraux. De telles altérations existent notamment chez les trilobites Phacopidae néodévoniens. Leur évolution est marquée par le « déplacement » progressif du complexe visuel vers les marges externes, accompagné du déplacement de la suture faciale. Cette évolution relève d'une pédomorphose. Ce caractère paraît adaptatif et se manifester dans de nombreuses lignées, entraînant entre celles-ci des convergences. Le phénomène de pédomorphose concerne également le changement dans le mode d'exuviation. Ce dernier caractère semble indépendant du milieu et représente un caractère hérité des formes ancestrales.

Modularity and integration are variational properties expressed at various levels of the biological hierarchy. Mismatches among these levels, for example developmental modules that are integrated in a functional unit, could be informative of how evolutionary processes and trade‐offs have shaped organismal morphologies as well as clade diversification. In the present study, we explored the full, integrated and modular spaces of two developmental modules in phacopid trilobites, the cephalon and the pygidium, and highlight some differences among them. Such contrasts reveal firstly that evolutionary processes operating in the modular spaces are stronger in the cephalon, probably due to a complex regime of selection related to the numerous functions ensured by this module. Secondly, we demonstrate that the same pattern of covariation is shared among species, which also differentiate along this common functional integration. This common pattern might be the result of stabilizing selection...

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Later Cambrian and earliest Ordovician trilobites and brachiopods spanning eight horizons from five localities within the Sông Mã, Hàm Rồng and Đông Sơn formations of the Thanh Hóa province of Việt Nam, constrain the age and faunal affinities of rocks within the Sông Đà terrane, one of several suture/fault-bounded units situated between South China to the north and Indochina to the south. ‘Ghost-like’ preservation in dolomite coupled with tectonic deformation leaves many of the fossils poorly preserved, and poor exposure precludes collecting within continuously exposed stratigraphic successions. Cambrian carbonate facies pass conformably into Lower Ordovician carbonate-rich strata that also include minor siliciclastic facies, and the recovered fauna spans several uppermost Cambrian and Lower Ordovician biozones. The fauna is of equatorial Gondwanan affinity, and comparable to that from South China, North China, Sibumasu and Australia. A new species of Miaolingian ‘ptychopariid’ tril...

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Trilobites from several horizons in the Florentine Valley Formation of the Tim Shea area *esi of Maydena, southwestern Tasmania are described and assigned late rremadoc to possibly early Arenig ages. I hen ayes approximate the Lancefieldian I a 1.5 /one of Psigraplus, La2 and possibly La3. raxa described are Hystricurus penchiensis Lu, //. lewisi (Kobayashi), //. sp, cf. //. rpbustus Ross,

Рассмотрены и проанализированы современные схемы стратиграфии Ордовика Великобритании, Северной Америки, Балто-Скандинавии, Австралии, Китая, Сибири, Средиземноморья и Северной Гондваны с точки зрения решений второй (Болонья, 1881), восьмой (Париж, 1900) и 27 (Москва, 1984) сессий международных геологическогих Конгрессов (МГК).
Они составлены, по мнению автора:
1) В соответствии с давно устаревшими решениями второй сессаии МГК и
2) С использованием стратиграфических терминов пионеров стратиграфической науки и практики второй половины Х1Х века: System / Period > Series / Epoch > Stage / Age.
В этой статье автор предлагает макет новой современной стратиграфической схемы ордовикской системы с учетом:
1) Всех требований восьмой сессии МГК и
2) Современной иерархии стратиграфических таксонов: Period / System > Epoch / Sub - System > Etap / Belt > Age / Tier > Phase / Zone (см. табл. 2, 3; рис. 3).

The aim of this study is to bridge a gap in the existence of Trilobites in the marine Permian successions of Iran by exploring a stratigraphic section of the Permian in Jamal Formation (Dizlu section).  Based on comprehensive field studies and laboratory investigations three Trilobite specimens were identified in the study area including Pseudophillipsia (Carniphillipsia) dizluensis sp. nov., Pseudophillipsia (Carniphillipsia) sagittalis and Pseudophillipsia (Carniphillipsia) sp.. A new occurrence of trilobites collected from the Permian (Wordian) Jamal Formation at a section at Dizlu, Isfahan Province, Iran, is documented.   They belong to a new species of Pseudophillipsia (Carniphillipsia), which is described herein, and can be attributed to the a group of species centered on P.(C). paffenholzi (Weber). It is based on 30 specimens from a single horizon, most of which are enrolled. Co-occurrence of Pseudophillipsia (Carniphillipsia) sp. A. and stenohalin groups such as brachiopods,...

In order to maximize the utility of future studies of trilobite ontogeny, we propose a set of standard practices that relate to the collection, nomenclature, description, depiction, and interpretation of ontogenetic series inferred from articulated specimens belonging to individual species. In some cases, these suggestions may also apply to ontogenetic studies of other fossilized taxa.

A Sequência Mesodevoniana-Eocarbonífera da Bacia do Parnaíba foi reinterpretada neste trabalho aplicando-se o modelo básico da estratigrafia de sequências. Foram analisados dados de poços e linhas sísmicas, elaborando-se a partir daí diagramas, mapas de isócoras e uma seção estratigráfica. Foram definidos dois ciclos de segunda ordem, referidos como sequências deposicionais 1 e 2 (SEQ1 e SEQ2). A SEQ1 inicia com o Trato de Sistemas de Nível Baixo (TSNB), constituído por conjuntos de parassequências progradacionais cujas litofácies indicam deposição em sistema deltaico sob influência de tempestades, tendo como limite superior a superfície regressiva máxima. O Trato de Sistemas Transgressivo (TST) caracteriza-se por conjuntos de parassequências retrogradacionais, compostos por pelitos de plataforma rasa depositados sob ação de tempestades. O Trato de Sistemas de Nível Alto (TSNA) apresenta conjuntos de parassequências progradacionais compostos por pelitos e arenitos depositados em amb...

AllsTRACT-The genus Otarion Zenker, 1833, first appears in the Wenlock simultaneously with Cyphaspis Burmeister, 1843, as the oldest known species of each occur together in the southern Mackenzie Mountains of the Canadian Northwest Territories. The genera are unambiguous sister groups, a relationship supported most compellingly by a uniquely derived and distinctive pattern of juvenile cephalie spines, shared also with the Carboniferous genus Namuropyge Richter and Richter, 1939. This sister group relationship permits the development of a robust and stratigraphically correlated hypothesis of relationship among the adequately known species of Otarion. Otarion, Cyphaspis, and Namuropyge constitute the tribe Otarionini. The Mississippian genus Dixiphopyge Brezinski, 1988, may also belong to Otarionini. Namuropyge is a paedomorph, likely derived from a Degree Six or Seven meraspid of an older species of uncertain position in the Otarion-Cyphaspis clade. Three Wenlock species of Otarion occur in stratigraphie succession in a single section in the Mackenzie Mountains. Analysis of morphological change with time, and of sequential ontogenies, suggests that the Silurian history of the genus was dominated by incidents of peramorphosis. New species are Otarion huddyi, O. beukeboomi, and O. coppinsensis. Otarion brauni Perry and Chatterton, 1979, is revised.