Trilobiten.de

[Jens]

Ich habe endlich ein lang vermisstes Zitat finden koennen, worin das Asaphus raniceps-Problem besprochen wird. Es gibt naemlich 2 Arten, naemlich einmal die Zonenleitart, die aber nicht der richtige Raniceps ist, sondern im Sinne von Angelin gebraucht wird.

BERGSTRÖM J., ZHI-QIANG Z., ZHI-YI Z. & WEN-WEI Y. 2003. The Asaphus raniceps problem in the Ordovician of Sweden. Bull. Geol. Soc of Denm. 50 : pp. 95 - 104.

[Jens]

Nicht ganz uninteressant, aber ohne Erwaehnung von Trilos. Aber vom Aussterben am Ende des Ordoviziums waren eben auch die Trilos arg betroffen (Agnostida, fast alle Asaphida, die letzten Ptychopariida). Tõnu Meidla ist uebrigens ein estnischer Ostrocoden-Spezialist, habe ihn in Greifswald kennengelernt.

Leho Ainsaar, Tõnu Meidla and Tõnu Martma (2004): The Middle Caradoc Facies and Faunal Turnover in the Late Ordovician Baltoscandian palaeobasin - Palaeogeography, Palaeoclimatology, Palaeoecology, 210 (2-4), 119-133.


Abstract
A Late Ordovician episode of remarkable biotic, climatic, sea level and facies changes, named here as the Middle Caradoc Facies and Faunal Turnover, took place in the Baltoscandian area. This paper presents an integrated overview of these changes in the critical middle Caradoc interval. Data are given on carbonate rock composition, distribution and grain-size composition of the siliciclastic material and the carbon isotopic composition of whole-rock carbonates in cores of Estonia and Sweden.

The Middle Caradoc Facies and Faunal Turnover can be described as a succession of related environmental changes. The turnover began with a positive excursion in carbonate 13C and continued with sea level changes that led to a sedimentary hiatus on the shelf and a change from carbonate-dominated to siliciclastic-dominated sedimentation in the basin. The turnover ended with an extinction event and associated microfaunal crisis.

The middle Caradoc turnover in Baltoscandia is comparable to a similar succession of changes in North America. The turnover affected two palaeocontinents, and reflects a widespread, possibly global environmental change. Onset of glaciation on Gondwana and/or increased orogenic activity might have initiated the changes in ocean circulation and led to the initial carbon isotope excursion. The following sea level rise and faunal changes affected several different continents.

[Jens]

Artyushkov, E.V., Lindström, M., & Popov, L.E. (2000): Relative sea-level changes in Baltoscandia in the Cambrian and early Ordovician: predominance of tectonic factors and the absence of large scale eustatic fluctuations. Tectonophysics, 320, pp. 35-407.

Dieses Zitat kann hilfreich sein fuer das Verstaendnis von Faziesaenderungen in Baltoscandia. Wir kennen aus dem oberen Mittelkambrium und Oberkambrium eine Menge von verschiedenen Konglomeraten aus verschiedenen Trilobitenzonen, die zeigen dass es zu mehrfach zu Aufarbeitungen gekommen ist. Schichtluecken sind besonders im Mittelkambrium weit verbreitet und ihre Ursache scheinen dem Artikel nach hauptsaechlich tektonischen Ursprungs zu sein. Wenn Land sich hebt, koennen halt keine marinen Sedimente abgelagert werden, es wird eher Vorhandenes abgetragen. Im Oberkambrium gibt es dann wieder mehrfach Trangressionen, die trockenliegende Bereiche wieder ueberflutet haben. So findet man Konglomerate in den die gruenen Kalke in Bruchstuecken in die oberkambrische Stinkkalkmatrix eingebettet sind.

[Jens]

Øyvind Hammer (2003): Biodiversity curves for the Ordovician of Baltoscandia. - Lethaia, 36 ( 4): 305 - 313.

Abstract:

Biodiversity curves for the Ordovician of Baltoscandia show a substantial increase in taxonomical diversity through the period, as seen also in global data sets. A database of 10,340 records of first and last appearances of species at different localities in the region has been analysed using simple species counts, and partly validated with resampling methods. While the biodiversity curve for all fossil groups combined is probably reasonably accurate except for an unknown scaling constant, taxonomical or geographical subsets may not be sufficiently well sampled to allow precise measurement of their species counts through time. The analysis shows a major diversification event commencing in the middle Arenig (Ibex-Whiterock boundary), and more limited diversification events in the Llanvirn, Caradoc and Ashgill. The Scandinavian (Norwegian and Swedish) biodiversity curves are broadly correlated with major changes in sea level, with low biodiversity at highstands and high biodiversity at lowstands, although this pattern is not clear for all fossil groups. In the Arenig, graptolites and trilobites appear to have higher diversities at high sea levels, while the brachiopods and ostracodes show higher diversities at low sea level. As a consequence, the Arenig diversification is delayed for the latter two groups until the upper end of the interval.

Geological Museum PO Box 1172 Blindern NO-0318 Oslo Norway

[Jens]

Hier ein interessantes Zitat, welches ich wohl bisher übersehen hatte.

Temple, J. T. (1952): A Revision of the trilobite Dalmanitina mucronata (Brongniart) and related species. : Lunds Universitets Årsskrift ; N.F. 2, 48 (1): p. ?, Lund : Gleerup.


Dalmanitina mucronata ist charakteristisch für den Dalmanitina-Schiefer im obersten Ashgill von Schweden. Ich glaube heute stellt man sie zu Mucronaspis, einem Kaltwasser-Genus, welches sich, bevorteilt durch die Abkühlung im Zuge der ordovizischen Vereisung schnell über große Gebiete ausbreitete und praktisch fast weltweit gefunden wurde.

Grüsse,

Jens

[Jens]

Für die Bestimmung baltischer Lichiiden geignet:

Holloway, D.J. & Thomas, A.T. (2002): Hoplolichoides, Allolichas, Autoloxolichas and Akantharges and the classification of lichid trilobites. - Geobios 35: 111-125.

Thomas A.T. & Holloway D.J. (1988): Classification and philogeny of the trilobite order Lichida – Philosophical Transaction of the Royal Society of London. B. Biological Sciences, 321: 179-262.


Grüsse,

Jens

[Jens]

Gunnar Henningsmoen (1960): The middle Ordovician of the Oslo region, Norway; 13, Trilobites of the family Asaphidae. - Norsk Geologisk Tidsskrift, 40 (3-4):203-258

Abstract:
Many middle Ordovician asaphid trilobites (including new species) are described, and ontogenetic stages of Ogygiocaris sarsi, certain glabellar features, and the tectonic deformation of fossils are discussed. Notes on the terminology and morphology of the asaphids are included, and the stratigraphic and geographic distribution of the middle Ordovician asaphids in the Oslo region is tabulated.


Gunnar Henningsmoen (1959): Rare Tremadocian trilobites from Norway. - Norsk Geologisk Tidsskrift, 39 (2-3): 153-174.

Abstract:
"Six rare trilobites from the Tremadocian Ceratopyge limestone in Norway are described. The genus Pagometopus (close to Orometopus) and the species Pagometopus gibbus and Peltocare modestum are new. The terminology for the exoskeletal plates of the cephalon is revised. A chart shows the stratigraphic occurrence of the Tremadocian trilobites recorded from Norway."


Leif Stoermer, Anatol Heintz, Gunnar Henningsmoen, Steinar Skjeseth, and Nils Spjeldnaes (1953): The middle Ordovician of the Oslo region, Norway; 1, Introduction to stratigraphy. - Norsk Geologisk Tidsskrift, 31: 37-141.

Abstract:
The lithology, stratigraphy, paleontology (with particular reference to characteristic fossils), and tectonics of the middle Ordovician of the Oslo area, Norway, are reviewed on the basis of sections in 11 districts between Langesund and Ringsaker and two additional areas. The various districts are compared, and the sequences are correlated with the standard graptolite zonal sequence. The term, middle Ordovician, is discussed. A historical review is given of paleontologic and stratigraphic investigations in the Oslo area. A survey of the middle Ordovician section is presented, and the variation in facies is discussed. The general paleogeographic features of the Oslo area are reviewed, a tentative stratigraphic scheme is presented, and a preliminary correlation between the area and corresponding sections in Sweden, the north Baltic, and Estonia is given.


Bertil Waern, Per Thorslund, and Gunnar Henningsmoen 1948): Deep boring through Ordovician and Silurian strata at Kinnekulle, Vestergoetland. - Bulletin of the Geological Institutions of the University of Uppsala, New Series (1948), 32: 337-473.

Abstract:
A series of papers describing the sequence, lithology, and faunal composition of the middle and upper Ordovician and lower Silurian strata traversed by a boring on the west slope of Kinnekulle mountain, Sweden. A preface, by Saeve-Soederbergh, and correlation tables, chemical analyses, descriptions of new genera and species of ostracods, trilobites, graptolites, and brachiopods, and bibliographies are included.

[Jens]

Endlich ist mal wieder jemand am Oberordoviz von Darlarna dran.

Yutaro Suzuki (2002): Trilobite assemblages of the Boda Limestone, Dalarna, Sweden. - (in First international palaeontological congress; abstracts). Abstracts - Geological Society of Australia (2002), 68: 282-283.

Yutaro Suzuki (2001): Revision of the Late Ordovician trilobite Holotrachelus punctillosus (Tornquist, 1884) from Dalarna, Sweden. -
Acta Palaeontologica Polonica, 46(3): 331-348.

Abstract:
Holotrachelus punctillosus from the Boda Limestone (Ashgill, Upper Ordovician) of Sweden is redescribed. The systematic position of this problematic species is discussed. Its distinctive morphology appears to be the result of an adaptation towards illaenid life habits. The pygidial morphology, with the extra-fulcral field developed as segmental pleural spines, makes an assignment possible to only four Ordovician groups, namely the Remopleuridioidea, Odontopleuroidea, Lichoidea and Cheiruroidea. Of these, the former three are so different that a direct affiliation is out of the question. Similarities with the Cheiruroidea are the more persuasive, particularly after a misinterpretation of the facial suture is corrected and some other problems are sorted out. It is suggested that the Holotrachelinae are placed within the Cheiruridae, where it may have special affinities to the Sphaerexochinae.

Yutaro Suzuki (2002): Systematic position and palaeoecology of a cavity-dwelling trilobite, Ityophorus undulatus Warburg, 1925, from the Upper Ordovician Boda Limestone, Sweden. - Paleontological Research, 6(1):73-83.

Abstract:
The high level systematic position and autecology of the Upper Ordovician cavity-dwelling trilobite Ityophorus undulatus is discussed. The lectotype is here selected from syntypes. The Late Cambrian family Loganellidae Rasetti, 1959 appears to contain the ancestors of this species. Ityophorus is compared with the closely related Middle Ordovician trilobite Frognaspis to pick out the stable characters. These are the yoked free cheeks, the wide cephalic doublure in combination with a distinct narrow cephalic rim, pygidial pleural and interpleural furrows, and a smooth mesial part of the inner cephalic doublural margin (lack of an embayment of the hypostomal suture). Because of the presence of several characteristics unique to the two, they are best attributed to a subfamily Ityophorinae, which is interpreted as a relict group of the Loganellidae. The discussion of the autecology is based on the structural relationship of the mouth opening and position of basal podomeres in relation to the cephalic margin, and on the functional morphology of terrace lines on the brim margin. The appendages appear to have been long to reach the substrate. The cephalon appears to have held the body rigidly by means of the terrace lines. This made it possible for the animal to use its appendages freely, for instance, in scratching the substrate. Some cavities in the present study area show evidence of a gel-like consistency of the cavity walls, which best fits the behavior mentioned above. Ityophorus is interpreted to have been an animal adapted to cavities rich in bacterial mats, on which it may have fed.


Yutaro Suzuki and Jan Bergstrom (1999): Trilobite taphonomy and ecology in Upper Ordovician carbonate buildups in Dalarna, Sweden. -
Lethaia, 32(2): 159-172.

Abstract:
A major ecological grouping of the trilobites in the Upper Ordovician Boda Limestone buildups in Dalarna is outlined, based primarily on the modes of occurrences in the Jutjarn quarry. The so-called pockets are analysed with regard to their trilobite contents and distribution within a carbonate buildup. The pockets are of two general types. One consists of narrow opened fissures along bedding planes. The matrix of these may contain either of the peculiar blind Isocolus sjoegreni or Ityophorus undulatus, both of which appear to have been cavernous species, possibly belonging to the Bathyuracea (or Leiostegiacea). In addition, small proetids used the fissures for moulting. The other kind of pocket is a cavity largely filled with sediment from the surface of the buildup. The size is considerable, in rare cases up to many tens of cubic metres. Although the buildups housed about 90 trilobite species, each of these pockets is dominated by one or two out of seven large species. Of these, six are illaenids, the seventh the illaenid-like cheirurid Holotrachelus punctillosus. Usually only pygidia and cranidia are found. These species may have lived gregariously around the rims of the cavities. The remaining species, about 85% of the trilobite fauna, appear to have lived on the surface of the buildups. The largest group is the proetids with some 20 species (in addition to those known from pockets). Cheirurinids and lichids contribute with some 15 species each, and there are six odontopleurids. The distinctness of the "community" is indicated by the circumstance that only three species are shared with contemporaneous level-bottom faunas in Sweden.

[Jens]

P. D. Lane (2002): The taxonomic position and coaptative structures of the Lower Ordovician trilobite Cyrtometopus. - (in Studies in Palaeozoic palaeontology and biostratigraphy in honour of Charles Hepworth Holland), Special Papers in Palaeontology, 67: 153-169.

Abstract:
The morphology of Cyrtometopus Angelin, 1854 from the Ordovician of Sweden, Norway and Ingria in Russia is described; the lectotype of the type species (Calymene? clavifrons Dalman, 1827) is figured for the first time, together with other conspecific material. It is argued that the Cyrtometopinae is not a natural taxonomic unit and should not be maintained, and that Cyrtometopus belongs to the Cheirurinae. Cyrtometopus is reconstructed in the enrolled position in which a pair of spines on the rostral plate form an unusual coaptative device with the spines of the pygidium. The binomen Cyrtometopus affinis Angelin, 1854 can be applied with certainty only to the unique holotype. "Cyrtometopus" aries, "Cyrtometopus" rosenthali, Cheirurus verrucosus, Ceraurinella peregrinus, and Reraspis? plautini are referred to Cyrtometopus, all with varying degrees of uncertainty.


Helje Parnaste (2004): Revision of the Ordovician cheirurid trilobite genus Reraspis with the description of the earliest representative. -
Proceedings of the Estonian Academy of Sciences, Geology = Eesti Teaduste Akadeemia Toimetised, Geoloogia , 53(2): 125-138.

Abstract:
The morphology of Reraspis Opik, 1937 is reviewed and compared with other cyrto-metopinines. Species previously referred to Reraspis are discussed and the generic composition is revised. Reraspis ranges from the Kunda (lower Middle Ordovician) to the Oandu (middle Upper Ordovician) Stage. It occurs in northern Estonia, Russia, and central Sweden (Dalarna). The earliest representative of the genus is the new species Reraspis orvikui from the Pakri Sandstone of Vaike-Pakri Island, NW Estonia. The genus also includes the type species R. plautini (Schmidt, 1881), R. latifrons (Warburg, 1925), and possibly R. kaljoi Mannil, 1958. Specimens from the Keila Stage of Estonia, originally referred to as Ceraurinella? cf. latifrons, are rather similar to R. latifrons and may either prove conspecific or closely related. Hemisphaerocoryphe? rosenthali (Schmidt, 1881) and Reraspis? kaljoi Mannil, 1958 share several characters with Reraspis and Cyrtometopella Nikolaisen, 1961, but a safe generic assignment requires better knowledge of the latter genus, especially concerning the pygidia. Reraspis? sexermis Opik, 1937 is better assigned to Xylabion Lane, 1971. The closely similar X. helgoeyense (Nikolaisen, 1961) may constitute a junior synonym. Remipyga? sp. sensu Mannil, 1958, [= Xylabion sp. (Mannil)] is also very closely related to Xylabion glaber. All three may in turn prove junior synonyms of Xylabion glaber (Angelin, 1854).


Torsten E. Tjernvik (1960): The lower Didymograptus shales of the Flagabro drilling core. - Geologiska Foereningen i Stockholm Foerhandlingar 82(2): 203-217

Abstract:
A description is given of the stratigraphic units and the graptolite (including Didymograptus deflexus scanicus n.subsp.) and trilobite fauna of the Arenigian (Ordovician) lower Didymograptus shales in a drill core from the Flagabro area in southeastern Skane, Sweden.


J. T. Temple (1952): The ontogeny of the trilobite Dalmanitina olini
Geological Magazine, 89: 251 - 262.

Abstract:
"The ontogeny of Dalmanitina olini Temple (upper Ordovician) is described on the basis of specimens from Scania [southern Sweden] and north Wales. The development is similar to that of D. socialis (Barrande), but good preservation has enabled some detailed changes in the cephalon to be followed. The protaspid and early post-protaspid stages bear an anterior pit in each axial furrow opposite the frontal lobe. The protaspid anterior glabellar furrow becomes joined to this pit by an oblique furrow, and forms with the latter a composite oblique furrow which develops into the adult anterior glabellar furrow. This mode of development is considered probably to be common to all phacopids; the significance of the anterior pits in this family is discussed. Preliminary observations are made on the growth-rates of various parts of the glabella, and the frontal lobe is found to grow in length (sag.) at a rate approximately equal to that of the rest of the glabella."

Ole A. Hoel and Magne Hoyberget (2002): The Lower Ordovician trilobite Megistaspis (Rhinoferus) hyorrhina (Leuchtenberg, 1843) (Trilobita) in Norway, with notes on its autecology. - Norsk Geologisk Tidsskrift, 82(2): 45-51.

Abstract:
The occurrence in the Arenig of the Oslo Region of the typically east Baltic trilobite Megistaspis (Rhinoferus) hyorrhina (Leuchtenberg, 1843) is confirmed. The Norwegian specimens exhibit a range of variation just as wide as that seen in the east Baltic. The visual field is estimated and found to overlap posteriorly and 20 degrees above horizontal. The glabellar tubercle in asaphids is considered to have functioned as a pressure-sensitive organ. The swelling of the posterior part of the glabella in some specimens, may have been to lift this organ as high as possible. This interpretation, together with the elevated eyes and the flattened exoskeleton, suggest a shallow infaunal life habit.