Upper Devonian (Frasnian stage) of the north-western part of the Russian Platform: paleomagnetic data

Paleomagnetic determinations for the Devonian strata of the Main Devonian Field, available in the international paleomagnetic data base, do not make it possible to construct both detailed magnetostratigraphic scales and reliable trajectories of the apparent polar wander path of the paleomagnetic pole. This is primarily due to the insufficient amount of data that determine modern reliability criteria. Obtaining more complete series of reliable paleomagnetic determinations is one of the important tasks of paleomagnetic studies. The paper presents new paleomagnetic determinations from a collection of rocks of the Frasnian stage of the Upper Devonian (Ilmen and Bureg Beds of the Semiluky Formation), sampled on the southern shore of Lake Ilmen, east of the village. Korostyn in 2009. Magnetomineralogical studies were carried out to determine the magnetic minerals of carriers of natural remanent magnetization. Three characteristic components of natural remanent magnetization have been identified. Two components correspond to the Late Paleozoic magnetization reversal (in the Carboniferous and Permian times). The third, bipolar component of the Frasnian age passes the reverse polarity test of the geomagnetic field.. The obtained position of the paleomagnetic pole by the bipolar component of the natural remanent magnetization is consistent with the available data on the section of the Late Upper Devonian of the Main Devonian Field.

A New Tristichopterid (Pisces, Sarcopterygii) from the Devonian of Latvia

A New Tristichopterid (Pisces, Sarcopterygii) from the Devonian of Latvia A new species of tristichopterid sarcopterygians, Eusthenopteron kurshi, sp. nov., the earliest representative of the family reported to this date from the territory known as the Main Devonian Field, is described from the well-known fossil locality of Latvia, the Lode clay quarry (Upper Givetian/Lower Frasnian). One complete skeleton and several disarticulated bone elements of the head and shoulder girdle have been found. The material reveals some morphologic features like a relatively short parietal shield in the cranial roof and rather asymmetric caudal fin. Characteristic features for the species are a front end of the squamosal extending comparatively far anteriorly and opercular being twice as high as the subopercular.

The unique fossil assemblage from the Lode Quarry (Upper Devonian, Latvia)

The unique fossil fauna from the Lode clay quarry, lower Frasnian, Latvia, includes a diverse ichthyofauna of at least 15 taxa of agnathans and gnathostomes, representing most of the major taxa of Devonian vertebrates. Six new fish taxa (five species and one genus) were discovered during the last ten years. Exceptionally well-preserved juvenile fishes (<i>Asterolepis ornata, Lodeacanthus gaujicus</i>) provide unique data on ontogenetic change. Diverse arthropods are recorded. Parasitic platyhelminth remains in juvenile fish bodies is their first discovery in the fossil record, and represents the oldest parasitic association ever found. A complete faunal and floral list for the Lode quarry is presented, with a detailed biostratigraphic section. Comparison of vertebrata taxa from the Gauja Regional Stage with similar of the Main Devonian Field, Scotland, Timan, Canada, and Germany is reviewed. <br><br> Die einzigartige Lebensgemeinschaft von Lode repräsentiert eine diverse Fischfauna nahezu aller Hauptwirbeltiertaxa, die im Devon lebten. Sechs neue Fischtaxa (5 Arten und 1 Gattung) wurden in den letzten zehn Jahren in den Unter-Frasnium-Schichten der Ziegeleigrube von Lode in Lettland entdeckt. Insgesamt sind 15 identifizierte und unbestimmte Fisch- und Agnathen-Arten von dort bekannt. Besondere Beachtung wurde den außergewöhnlich gut erhaltenen Jugendformen von <i>Asterolepis ornata</i> und <i>Lodeacanthus gaujicus</i> und verschiedenen Invertebraten (Crustacea, Merostomata) gespendet, die in einer einzigen Linse fein verteilten Tones gefunden wurden. Reste parasitischer Platyhelminthen, die in Jungfischen auftreten, wurden hier zum ersten Mal als Fossilien entdeckt; sie repräsentieren die älteste bisher gefundene parasitische Gemeinschaft. Eine Liste der organischen Reste aus den Schichten der Ziegeleigrube Lode wird präsentiert. Ein detailliertes biostratigraphisches Profil wird beschrieben. Die Fischfaunen aus der Gauja Regional-Stufe werden mit denen vom Hauptdevonfeld Russlands, von Schottland, dem Timan, Kanadas und Deutschlands verglichen. <br.><br> doi:<a href="http://dx.doi.org/10.1002/mmng.20010040108" target="_blank">10.1002/mmng.20010040108</a>