Trilobiten.de

[Jens]

KIM, DONG HEE, WESTROP, STEPHEN R., LANDING, ED (2002): Middle Cambrian (Acadian Series) Conocoryphid and Paradoxidid trilobites from the Upper Chamberlain& S Brook Formation, Newfoundland and New Brunswick. - Journal of Paleontology Volume: 76 (5): 822-842.

ABSTRACT

The Fossil Brook Member of the upper Chamberlain's Brook Formation is a thin (up to 14 m) but distinctive, unconformity-bound depositional sequence recognizable from Rhode Island to eastern Newfoundland in Avalonian North America. Its diverse trilobite fauna was first described more than century ago from the limestone-rich facies of the member in southern New Brunswick. However, the systematics, stratigraphic context, and biostratigraphic significance of these trilobites have remained poorly known. A revision of the conocoryphid and paradoxidid trilobites has been completed, and the taxa set into their stratigraphic context within the middle Middle Cambrian. The faunas of the Fossil Brook are assigned to the Eccaparadoxides eteminicus Zone of Avalon. Although biogeographic barriers between Avalon and Gondwana remained strong in the Middle Cambrian and few shared trilobite species are present, a generalized correlation of the E. eteminicus Zone into Gondwana is with the Badulesia tenera Zone of the Toushamian Stage in Morocco and the Badulesia Zone of the Caesaraugustian Stage in Spain.

[Jens]

Unter dieser url findet man eine Reihe von Abstracts über Trilobiten:


http://www.bioone.org/bioone/?request=search-results&searchtype=simple&issn=All&year_start=&month_start=01&year_
end=&month_end=12&title_boolean=ALL&title=trilobite&abstract_boolean
=ALL&abstract=&body_boolean=ALL&body=&biblist_boolean=ALL&biblist=
&fname_boolean=ALL&fname=&lname_boolean=ALL&lname=&hits_per_pa
ge=10&sort=relevance&previous_hit=0

Grüsse,

Jens

[Jens]

Eigentlich handelt es sich bei dem unten folgenden Abstract nicht um eine Trilobiten-relavante Publikation, sondern es geht um die Naroiida (Nektaspida). Interessant ist, daß diese Gruppe nun erstmals aus dem Silur und zwar in Ontario (Canada) nachgewiesen wurde. Bisher nahm man an, daß die "weichhäutige" Schwestergruppe der Trilobiten am Ende des Ordoviziums ausgestorben sei.

JEAN-BERNARD CARON,a DAVID M. RUDKIN,b and STUART MILLIKENc (2004): A NEW LATE SILURIAN (PRIDOLIAN) NARAOIID (EUARTHROPODA: NEKTASPIDA) FROM THE BERTIE FORMATION OF SOUTHERN ONTARIO, CANADA—DELAYED FALLOUT FROM THE CAMBRIAN EXPLOSION. - Journal of Paleontology: Vol. 78, No. 6, pp. 1138–1145.



a) Department of Zoology, Ramsay Wright Zoological Laboratories, University of Toronto, Ontario M5S 3G5, Canada, <E-mail: jcaron@rom.on.ca>
b) Department of Palaeobiology, Royal Ontario Museum, Toronto M5S 2C6
c) 148 East Avenue, Brantford, Ontario N3S 3M4

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ABSTRACT—The discovery of a new naraoiid nektaspid in the Upper Silurian (Pridolian) of southeastern Ontario significantly extends the range of this unusual group. Nektaspids are nonmineralized arthropods typical of Early and Middle Cambrian soft-bottom communities, but were thought to have become extinct in the Late Ordovician. The unique holotype specimen of Naraoia bertiensis n. sp. comes from a Konservat–Lagerstätte deposit renowned for its eurypterid fauna (the Williamsville Member of the Bertie Formation). Naraoia bertiensis lacks thoracic segments and is morphologically similar to Naraoia compacta from the Middle Cambrian Burgess Shale, save for the presence of a long ventral cephalic doublure and a subtly pointed posterior shield. To examine the phylogenetic relationships of the new naraoiid, we coded characters of the holotype specimen and of nine previously described nektaspids. The results confirm a sister taxon relationship between Naraoia compacta and Naraoia bertiensis and the monophyly of nektaspid forms lacking thoracic segments (family Naraoiidae). This latter group may have arisen from an ancestral segment-bearing form through heterochronic loss of thoracic segments early in the Cambrian. The disjunct occurrence of a naraoiid nektaspid in the Late Silurian resembles the reappearance of other “Lazarus taxa” that were thought to have been eliminated during mass extinction events. The naraoiid lineage survived the Late Ordovician biotic crisis, but in this case the “Lazarus effect” seems likely to be taphonomic in origin.

Grüsse,

Jens

PS: Thanks to Jhcook from the Yahoo-trilobite-Forum for finding this article.

[Jens]

Der folgene Artikel behandelt die Lithostratigraphie des Burgess-Shales.

Terence P. Fletcher and Desmond H. Collins (1998): The Middle Cambrian Burgess Shale and its relationship to the Stephen Formation in the southern Canadian Rocky Mountains. - Can. J. Earth Sci./Rev. Can. Sci. Terre 35(4): 413-436.

Abstract: The Burgess Shale has been an anomalous geologic unit ever since Walcott named it in 1911 as the geographic equivalent of the Ogygopsis Shale in the Middle Cambrian Stephen Formation of southeastern British Columbia, but it has never been recognized outside of its type locality, so its status relative to the Stephen Formation remained uncertain. The geologic setting of the Burgess Shale was determined by Aitken and Fritz in 1968, when they recognized the Cathedral Escarpment and divided the Stephen Formation into a "thin" platformal succession on top of the Escarpment, and a "thick" basinal succession, which included Walcott's Burgess Shale, in front. Fieldwork by Royal Ontario Museum parties between 1982 and 1997 has now demonstrated that the thin and thick Stephen successions lie within different facies belts and should be regarded as separate formations; the Stephen Shale Formation is part of the Middle Carbonate Belt succession, whereas the name Burgess Shale Formation is applied to the thick basinal succession within the Outer Detrital Belt Chancellor Group. Ten distinct members are recognized in the Burgess Shale: Kicking Horse Shale, Yoho River Limestone, Campsite Cliff Shale, Wash Limestone, Walcott Quarry Shale, Raymond Quarry Shale, Emerald Lake Oncolite, Odaray Shale, Paradox Limestone, and Marpole Limestone. In contrast to the Stephen Shale Formation with its nonsequences, the thicker Burgess Shale Formation seems to represent continuous deposition spanning the Glossopleura to Bathyuriscus-Elrathina zonal boundary, incorporating the Polypleuraspis insignis and Pagetia bootes subzones and the main part of the Pagetia walcotti subzone.

[Jens]

Und da gibts noch mehr:

Terence P. Fletcher and Desmond H. Collins (2003): The Burgess Shale and associated Cambrian formations west of the Fossil Gully Fault Zone on Mount Stephen, British Columbia. - Can. J. Earth Sci./Rev. Can. Sci. Terre 40(12): 1823-1838.

Abstract: West of the Fossil Gully Fault Zone on Mount Stephen, the three lowest members only of the Burgess Shale Formation are preserved: the Kicking Horse Shale, the Yoho River Limestone, and the Campsite Cliff Shale. The formation rests unconformably upon the Takakkaw Tongue Formation, whose dark basinal limestones conformably overlie paler shelf-like limestones of the Mount Whyte Formation. Mapping has resolved a long-standing problem and shown that the stratigraphical position of the famous Mount Stephen Trilobite Beds lies within the Campsite Cliff Shale. It has also revealed some of the complexities of the Fossil Gully Fault Zone, among which different periods and directions of component fault movements are indicated. Faunal evidence shows that the Plagiura–Kochaspis to Albertella and Albertella to Glossopleura zonal boundaries lie within the Takakkaw Tongue sequence. Within the Burgess Shale, three distinct soft-bodied communities occur at different stratigraphical levels on this mountain slope. The oldest, characterized by the arthropod Alalcomenaeus and chelicerate Sanctacaris, occurs low in the Kicking Horse Shale Member and is best known from Collins Quarry. The others lie within the Campsite Cliff Shale Member. The Trilobite Beds, characterized by claws of the dinocarid Anomalocaris and moults of the trilobite Ogygopsis klotzi, onlap the sloping top of a proximal bench facies of the Yoho River Limestone Member close to the Cathedral Escarpment. Slightly older and farther out in the basin are beds characterized by the dinocarid Laggania and a tulip-like animal related to Dinomischus, excavated about 12 m above the top of a thin distal wedge facies of the Yoho River Limestone at the S7 site. Among the illustrated trilobites, a new corynexochine from the Campsite Cliff Shale Member is figured.

[Jens]

Hier sind eine Reihe interessanter Abstracts von Vorträgen zum Thema:

Reconstructing the Cambrian World: Temporal and Spatial Changes in Physical and Biotic Environments. - Ed Landing and Gerd Geyer, Presiding.

Das Vortragsprogramm stammt von der Jahrestagung der Geological Society of America in Denver (Colorado), October 27-30, 2002).


http://gsa.confex.com/gsa/2002AM/finalprogram/session_3076.htm

[Jens]

Now something for our american visitors:


WESTROP, STEPHEN R. & LANDING, ED (2000): LOWER CAMBRIAN (BRANCHIAN) TRILOBITES AND BIOSTRATIGRAPHY OF THE HANFORD BROOK FORMATION, SOUTHERN NEW BRUNSWICK. - Journal of Paleontology, 74 (5): 858-878.

ABSTRACT

The Hanford Brook Formation, one of the classic Cambrian units of Avalonian North America, contains at least eight species of endemic trilobites, including Berabichia milleri Westrop n. sp., that are assigned to seven genera. The vertical succession of faunas is far more complex than has been recognized previously, with each member containing a lithofacies-specific assemblage. These are, in ascending order: a bradoriid-linguloid Association without trilobites in the nearshore St. Martin's Member, a Protolenus Association in dysaerobic siltstones and sandstones of the Somerset Street Member, and a Kingaspidoides-Berabichia Association in hummocky cross-stratified sandstones of the Long Island Member that overlie a parasequence boundary at Hanford Brook. Due to the breakdown of biogeographic barriers in the late Early Cambrian, two new species-based zones, the Protolenus elegans and Kingaspidoides cf. obliquoculatus zones, share trilobite genera with the Tissafinian Stage of Morocco. This generic similarity has been the basis for correlation of this upper Lower Cambrian interval on the Avalon continent with the West Gondwanan lowest Middle Cambrian. However, the clear facies control on the occurrence of genera in the Hanford Brook Formation and the presence of an abrupt faunal break and unconformity at the base of the Tissafinian in Morocco makes this correlation questionable. The Hanford Brook Formation may represent a late Early Cambrian interval unknown in Gondwana. Sequence-stratigraphic criteria even raise the possibility that the Protolenus Association is the biofacies equivalent of Callavia broeggeri Zone faunas of the Brigus Formation of Newfoundland, Nova Scotia and Massachusetts.

regards,

Jens

[Jens]

LIEBERMAN, BRUCE S. 2002: PHYLOGENETIC ANALYSIS OF SOME BASAL EARLY CAMBRIAN TRILOBITES, THE BIOGEOGRAPHIC ORIGINS OF THE EUTRILOBITA, AND THE TIMING OF THE CAMBRIAN RADIATION. Journal of Paleontology: Vol. 76, No. 4, pp. 692–708


ABSTRACT

This paper presents a phylogenetic analysis of the “Fallotaspidoidea,” a determination of the biogeographic origins of the eutrilobites, and an evaluation of the timing of the Cambrian radiation based on biogeographic evidence. Phylogenetic analysis incorporated 29 exoskeletal characters and 16 ingroup taxa. In the single most parsimonious tree the genus Fallotaspidella Repina, 1961 , is the sister taxon of the sutured members of the Redlichiina Richter, 1932 . Phylogenetic analysis is also used to determine the evolutionary relationships of two new species of “fallotaspidoids” distributed in the White-Inyo Range of California that have been previously illustrated but not described. These species had been referred to Fallotaspis Hupé, 1953 , and used to define the occurrence of the eponymous Fallotaspis Zone in southwestern Laurentia. However, these two new species need to be reassigned to Archaeaspis Repina in Khomentovskii and Repina, 1965 . They are described as Archaeaspis nelsoni and A. macropleuron. Their phylogenetic status suggests that the Fallotaspis Zone in southwestern Laurentia is not exactly analogous to the Fallotaspis Zone in Morocco, where that division was originally defined. Thus, changes to the biostratigraphy of the Early Cambrian of southwestern Laurentia may be in order. Furthermore, specimens of a new species referable to Nevadia Walcott, 1910 , are recognized in strata traditionally treated as within the Fallotaspis Zone, which is held to underlie the Nevadella Zone, suggesting further biostratigraphic complexity within the basal Lower Cambrian of southwestern Laurentia.

Phylogenetic analyses of the Olenellina and Olenelloidea, along with the phylogenetic analysis presented here, are used to consider the biogeographic origins of the eutrilobites. The group appears to have originated in Siberia. Biogeographic patterns in trilobites, especially those relating to the split between the Olenellid and Redlichiid faunal provinces are important for determining the timing of the Cambrian radiation. Some authors have argued that there was a hidden radiation that significantly predated the Cambrian, whereas others have suggested that the radiation occurred right at the start of the Cambrian. The results from trilobite biogeography presented here support an early radiation. They are most compatible with the notion that there was a vicariance event relating to the origin of the redlichiinid trilobites, and thus the eponymous Redlichiid faunal province, from the “fallotaspidoids,” whose representatives were part of the Olenellid faunal province. This vicariance event, based on biogeographic patterns, is likely related to the breakup of Pannotia which occurred sometime between 600–550 Ma, suggesting that the initial episodes of trilobite cladogenesis occurred within that interval. As trilobites are relatively derived arthropods, this suggests that numerous important episodes of metazoan cladogenesis precede both the earliest trilobitic part of the Early Cambrian, and indeed, even the Early Cambrian.



KIM, DONG HEE, WESTROP, STEPHEN R., LANDING, ED. 2002: MIDDLE CAMBRIAN (ACADIAN SERIES) CONOCORYPHID AND PARADOXIDID TRILOBITES FROM THE UPPER CHAMBERLAIN'S BROOK FORMATION, NEWFOUNDLAND AND NEW BRUNSWICK. Journal of Paleontology: Vol. 76, No. 5, pp. 822–842.

ABSTRACT

The Fossil Brook Member of the upper Chamberlain's Brook Formation is a thin (up to 14 m) but distinctive, unconformity-bound depositional sequence recognizable from Rhode Island to eastern Newfoundland in Avalonian North America. Its diverse trilobite fauna was first described more than century ago from the limestone-rich facies of the member in southern New Brunswick. However, the systematics, stratigraphic context, and biostratigraphic significance of these trilobites have remained poorly known. A revision of the conocoryphid and paradoxidid trilobites has been completed, and the taxa set into their stratigraphic context within the middle Middle Cambrian. The faunas of the Fossil Brook are assigned to the Eccaparadoxides eteminicus Zone of Avalon. Although biogeographic barriers between Avalon and Gondwana remained strong in the Middle Cambrian and few shared trilobite species are present, a generalized correlation of the E. eteminicus Zone into Gondwana is with the Badulesia tenera Zone of the Toushamian Stage in Morocco and the Badulesia Zone of the Caesaraugustian Stage in Spain.

[Jens]

Now back to Scandinavia:

Euan N.K. Clarkson; John Ahlgren; Cecilia M. Taylor (2004): Ontogeny, structure and functional morphology of some spiny Ctenopyge species (Trilobita) from the upper Cambrian of Västergötland, Sweden. -Transactions: Earth Sciences, 94 (2): pp. 115-143; Edinburgh .

Abstract:

This paper completes the description of intact and three-dimensional Ctenopyge species from the upper Cambrian Peltura minor Zone in Västergötland, central Sweden. All these species are present together, on the same bedding planes. The most abundant species, Ctenopyge (Eoctenopyge) angusta Westergård, 1922 has previously been described, and an almost complete ontogeny worked out. C. (Ctenopyge) gracilis Henningsmoen, 1957 is a small trilobite with nine thoracic segments and very long, thin curving and subparallel thoracic spines; the genal spines partially encircle the body. Two axial spines at the rear are of considerable length. When reconstructed in side view, the posterior thoracic spines rise upwards as an inclined fan, but when relaxed the tips of all the thoracic and axial spines come to lie in the same plane as the horizontal genal spines. An almost complete ontogeny is described for this species, and individuals show an evident spinosity from an early stage, but the body size at which thoracic segments are liberated is highly variable. C. (Ctenopyge) ahlbergi n. sp. is a larger, robust and broad species distinguished by long, stout genal spines, ten thoracic segments, and a very spiny body with the first three to four spines expanded into lateral flanges. A degree 6 meraspis shows these flanges already developing. C. (Ctenopyge) rushtoni n. sp has likewise ten thoracic segments, and has stout, broad-based and tapering spines. Incomplete meraspides 6 and 7 are known for this species. In both C. (Ctenopyge) ahlbergi and C. (Ctenopyge) rushtoni there are also two axial spines at the rear, and the extended body would have had a similar rising tail fan to that of C. (Ctenopyge) gracilis. C. (Mesoctenopyge) tumida is also present as a single large adult and several smaller holaspides. In this species the first thoracic segment is confirmed as bearing a pair of long curving spines, somewhat smaller than the encircling genal spines. The remaining thoracic spines are straight and sharp, and evidently longer in young holaspides. There is a single long axial spine on the last segment. No adult pygidium has been found.

Some comments on the diversity of the fauna as a whole and the range of functional types are appended.

[Jens]

Hier ist noch ne gute Suchmaschine für Trilo-Zitate:

http://www.ingentaconnect.com/search?title=trilobite&database=1

Da kann sich jeder was raussuchen, ich geh jetzt nach Hause.

Grüsse,

Jens

[Jens]

Hier was über Lichiden vom Altmeister der Trilobitenkunde:

H. B. WHITTINGTON (2002): LICHIDAE (TRILOBITA): MORPHOLOGY AND CLASSIFICATION. - Journal of Paleontology: Vol. 76, No. 2, pp. 306–320.


Author: Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, United Kingdom

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ABSTRACT

Morphology is reviewed with special reference to the doublure and thoracic characters; a reconstruction of Richterarges aquilonius is used to suggest possible lichid anatomy. The relatively large hypostome and wide doublure, and the thorax with, or without, the strongly convex posterior pleural bands characterize lichids, in addition to the distinctive glabellar morphology. Relatively shallow furrows on the external surface form strong ridges on the visceral surface of the exoskeleton; apodemes are absent. Type specimens of species described by Schmidt, recently traced in Russian museums, are figured. Lichids differ from odontopleurids in morphology and anatomy, and are unlike Scutelluinae; accepted subfamilial divisions of Lichidae are reinforced by thoracic characters. A single lichid species is known in the early Tremadoc, in the early Middle Ordovician the main four subfamilies are recognised and are widespread; their ancestry and early diversification remain unknown.


Grüsse,

Jens

[Jens]

Ich habe ein paar schwedische und norwegische Zitate (vorwiegend Kambrium) gefunden, hier erstmal Suchresultate in Verbindung mit Henningsmoen:


Gunnar Henningsmoen (1957): A trilobite with North American affinities from the upper Cambrian of Sweden. - Bulletin of the Geological Institutions of the University of Uppsala, New Series, 37 (1-2): 167-171

Abstract:
"Taenicephalus? peregrinus n.sp. is described from the upper Cambrian Olenus beds in Sweden. It recalls North American genera of the families Pterocephalidae and Parabolinoididae, and is regarded as one of the rare occasional invaders into the upper Cambrian sea of Scandinavia."


F. Nikolaisen and G. Henningsmoen (1990): Lower and Middle Cambrian trilobites from the Digermul Peninsula, Finnmark, Northern Norway
Bulletin - Norges Geologiske Undersokelse, 419: 55-95.

F. Nikolaisen and G. Henningsmoen (1985): Upper Cambrian and lower Tremadoc olenid trilobites from the Digermul Peninsula, Finnmark, Northern Norway. - Bulletin - Norges Geologiske Undersokelse, 400: 1-49.

G. Henningsmoen, V. Jaanusson, I. W. B. Nye, and C. J. Stubblefield (1980): Ogygiocaris Angelin, 1854, and Ogygites Tromelin and Lebesconte, 1876 (Trilobita); proposed conservation under the plenary powers; Z.N.(S.) 439. - Bulletin of Zoological Nomenclature (February 1980), 36, Part 4 226-230.


Gunnar Henningsmoen (1958): The upper Cambrian faunas of Norway, with descriptions of non-olenid invertebrate fossils. - Norsk Geologisk Tidsskrift, 38(2): 179-196.

Abstract:
Describes non-olenid trilobites and nonarthropod invertebrates from the upper Cambrian Olenid series in Norway and presents tables of the stratigraphic and geographic distribution of the faunal elements of the series.


Gunnar Henningsmoen (1955): Boeckaspis, new name for Boeckia Broegger 1882, non Malm 1870. - Norsk Geologisk Tidsskrift, 161.

Abstract:
The name Boeckaspis is proposed for trilobites previously assigned to the preoccupied genus Boeckia, with Boeckia hirsuta as the type species.


Gunnar Henningsmoen (1952): Et nytt funn av kambriske fossiler pa Vestlandet. - Arbok - Norske Videnskaps-Akademi: 12-13.

Abstract:
The first discovery of Cambrian fossils on the west coast of Norway is reported--in Hjelmeland, Rogaland. The fossils are of early middle Cambrian age. During this time dry land extended from the Mjoesa area to Bornholm.


Gunnar Henningsmoen (1952): Early middle Cambrian fauna from Rogaland, SW Norway (Paradoxides oelandicus stage = 1 c alpha). -
Norsk Geologisk Tidsskrift, 30: 13-31.

Abstract:
Describes Cambrian fossils--trilobites (including Ptychoparia anderseni n.sp.), brachiopods, hyolithids, sponge needles, and Problematica (including archeocyathids?)--from the Hjelmeland district, Rogaland, western Norway. The fossils occur in an autochthonous dark shale. The fauna is discussed, and a list of fossils from the Paradoxides oelandicus stage in Norway is presented.


Gunnar Henningsmoen (1951): Remarks on the classification of trilobites. - Norsk Geologisk Tidsskrift, 29: 174-217

Abstract:
The classification and phylogenetic relationships of trilobites are discussed. A number of superfamilies (Agnostacea, Zacanthoidacea, Olenellacea, Redlichiacea, Conocoryphacea, Asaphacea, Dikelocephalacea, Odontopleuracea, Calymenacea, Raphiophoracea, Phacopacea, Cheiruracea) are recognized, and their characteristic morphologic features are reviewed, with special reference to features of taxonomic importance. A list of most families, arranged in superfamilies, and a table suggesting the relationships of the major trilobite groups are presented.

Grüsse,

Jens

[Jens]

Skandinavische Triloliteratur aus dem Kambrium.

Per Ahlberg (1980): Early Cambrian trilobites from northern Scandinavia
Norsk Geologisk Tidsskrift, 60(3): 153-159.

Per Ahlberg (1981): Ptychopariid trilobites in the Lower Cambrian of Scandinavia. - (in Short papers for the Second international symposium on the Cambrian System, Taylor,) Open-File Report - U. S. Geological Survey: 5-7.

P. Ahlberg (1983): Lower Cambrian trilobites from the Laisvall area, northern Sweden. - Geologiska Foereningen i Stockholm Foerhandlingar, 105(3): 251-259.

P. Ahlberg (1983): A Lower Cambrian trilobite fauna from Jaemtland, central Scandinavian Caledonides. - Geologiska Foereningen i Stockholm Foerhandlingar, 105(4):349-361.

P. Ahlberg (1983): Redescription of a Lower Cambrian eodiscid trilobite from Norway. - Norsk Geologisk Tidsskrift, 63(4):289-290.

Per Ahlberg (1998): Cambrian shelly faunas and biostratigraphy of Scandinavia (in Guide to excursions in Scania and Vastergotland, southern Sweden, Ahlberg,) - Lund Publications in Geology, 141: 5-9.

Per Ahlberg and J. Bergstrom (1982): Lower Cambrian trilobites from southern Swedish Lapland. - Geologiska Foereningen i Stockholm Foerhandlingar, 104(3):241-246.

P. Ahlberg and J. Bergstrom (1993): The trilobite Calodiscus lobatus from the Lower Cambrian of Scania, Sweden. Geologiska Foereningen i Stockholm Foerhandlingar, 115(4): 331-334.

John Ahlgren and Per Ahlberg (1996): Olenus henningsmoeni, a new trilobite from the Upper Cambrian of Vaestergoetland, Sweden. - GFF 118(2): 73-77.

Per Ahlberg, Jan Bergstroem, and Jan Johansson (1986): Lower Cambrian olenellid trilobites from the Baltic faunal province. -
Geologiska Foereningen i Stockholm Foerhandlingar, 108 (1):39-56.

Jan Bergstroem and Per Ahlberg (1981): Uppermost Lower Cambrian biostratigraphy in Scania, Sweden. - Geologiska Foereningen i Stockholm Foerhandlingar, 103(2):193-214.

Adrian W. A. Rushton and Thomas Weidner (2002): A review of the trilobite Dolichometopus svecicus from the Middle Cambrian of Sweden. -
GFF, 124(2): 103-106.

P. H. Whitworth (1970): Ontogeny of the upper Cambrian trilobite Leptoplastus crassicornis (Westergaard) from Sweden. - Palaeontology, 13, Part 1: 100-111.

J. E. Dalingwater, S. J. Hutchinson, H. Mutvei, and David J. Siveter (1991): Cuticular ultrastructure of the trilobite Ellipsocephalus polytomus from the Middle Cambrian of Oeland, Sweden. - Palaeontology, 34(1): 205-217.

H. Huisman (1982): Enkele trilobietenvindplaatsen in de boven-cambrische Aluinschalie in Zweden. - Grondboor en Hamer 1982(6):157-164.

J. O. R. Ebbestad, P. Ahlberg, and M. Hoyberget (2003): Redescription of Holmia inusitata (Trilobita) from the Lower Cambrian of Scandinavia. - Palaeontology, 46, Part 5: 1039-1054.

P. Ahlberg (1985): Lower Cambrian trilobite faunas from the Scandinavian Caledonides; a review (in The Caledonide Orogen; Scandinavia and related areas; Vol. 1, Gee,). - John Wiley & Sons, Chichester, United Kingdom: 339-346.


P. Ahlberg (2003): Trilobites and intercontinental tie points in the Upper Cambrian of Scandinavia (in Advances in the knowledge of the Cambrian system, Acenolaza,). - Geologica Acta, 1(1): 127-134.

Abstract:
The Upper Cambrian faunas of Scandinavia are generally dominated by olenid trilobites, which provide a firm basis for the biostratigraphic classification. The olenids tend, however, to be provincial and facies controlled. By contrast, many agnostoid genera and species have a nearly worldwide distribution and are excellent biostratigraphic indices in Middle and Upper Cambrian strata. Three distinctive and geographically widely distributed agnostoid species are known from the lower part of the Upper Cambrian in Scandinavia: Linguagnostus reconditus Poletaeva and Romanenko, 1970, Aspidagnostus lunulosus (Kryskov in Borovikov and Kryskov, 1963), and Glyptagnostus reticulatus (Angelin, 1851). They are the most valuable species available for correlations with Upper Cambrian deposits outside Baltica. L. reconditus is seemingly confined to the Agnostus pisiformis Zone and provides strong evidence for correlation of that zone with the recently defined L. reconditus Zone of Peng and Robison. G. reticulatus appears in the Olenus gibbosus Subzone and ranges up into the O. wahlenbergi Subzone, suggesting that the lower part of the Olenus/Agnostus (Homagnostus) obesus Zone correlates with the G. reticulatus Zone in, e.g., Australia, China, and Kazakhstan. The presence of A. lunulosus in the O. gibbosus Subzone provides additional evidence for this correlation. Higher in the sequence agnostoids become rare, and the species recorded from the medial and upper Upper Cambrian of Baltica permit only broad correlations with other continents.

Mikael Erlstrom, Per Ahlberg, and Anita Lofgren (2001): Lower Palaeozoic stratigraphy at Lyby and Tangelsas, central Scania, southern Sweden. -
GFF, 123(1): 7-14.

Euan N. K. Clarkson, Per Ahlberg, and Cecilia M. Taylor (1998): Faunal dynamics and microevolutionary investigations in the Upper Cambrian Olenus Zone at Andrarum, Skane, Sweden. - GFF , 120(3): 257-267.

[Jens]

Hier spannende Zitate:

L. Ramsköld (1991): The perforated trilobite Laethoprusia gen. nov., and the phylogeny of Koneprusia and Isoprusia (Odontopleuridae, Koneprusiinae). - Transactions of the Royal Society of Edinburgh: Earth Sciences, 82(2): 125-141.

L. Ramskold and G. D. Edgecombe (1991): Trilobite monophyly revisited. - Historical Biology, 4(4): 267-283.

Gregory D. Edgecombe, and Lars Ramskold (1999): Relationships of Cambrian Arachnata and the systematic position of Trilobita. - Journal of Paleontology; 73 (2): 263-287.

Cladistic relationships of Trilobita, Naraoiidae (five ingroup taxa), Helmetiida (five ingroup taxa), Xandarellida, and the Cambrian arachnates Retifacies, Sinoburius, Emeraldella, and Sidneyia are investigated based on 29 characters. Documentation of appendage morphology and other ventral structures in Saperion from the Chengjiang fauna permits an appraisal of helmetiid relationships. A monophyletic Trilobita [= "Olenellida" (Emuellida + Eutrilobita)] is defined by numerous synapomorphies, including exoskeletal calcification and dorsal eyes with calcified lenses and circumocular sutures. Helmetiida is a robust clade, resolved as (Helmetiidae (Tegopeltidae (Saperiidae + Skioldiidae))). Naraoiid monophyly is well-supported, but neither a naraoiid-trilobite nor a naraoiid-Retifacies clade are parsimonious, the latter grouping ("Nectopleura") being explicitly paraphyletic. A sister group relationship between Xandarellida and Sinoburius is endorsed, although character support is novel compared to previous groupings of these taxa. The fourth postantennal limb pair in trilobites, naraoiids, and apparently helmetiids is based beneath the cephalothoracic articulation. Reweighted characters favor Trilobita and Helmetiida as closest relatives, with Petalopleura and then araoiidae as sister groups.


Jonathan M. Adrain, Stephen R. Westrop, Brian D. E. Chatterton, and Lars Ramskold (1998): Silurian trilobite alpha diversity and the end-Ordovician extinction. - (in Geological Society of America, 1998 annual meeting, Anonymous,) Abstracts with Programs - Geological Society of America, 30(7): 285.

Abstract:
A new data set of 126 collections yielding 25,000 trilobites, mostly from Laurentia, eastern Avalonia, and Baltica, provides a record of within-habitat (alpha) species diversity during the Silurian through a spectrum of shelf environments. The end-Ordovician extinction had surprisingly little impact on long-term alpha diversity trends in Laurentia: apart from a brief drop in the Ordovician-Silurian boundary interval, the number of trilobite species in local habitats between the Llandovery and the Ludlow remained at levels no lower than those of both the Late Cambrian and the Middle Ordovician. Recovery from the end-Ordovician event was achieved well before the end of the Llandovery. Laurentian trilobite alpha diversity during each series of the Silurian is not significantly different from levels for shelf habitats in other parts of the world. An earlier analysis of the Ordovician of Laurentia is now supplemented by a dataset of Middle and Late Ordovician collections from other paleocontinents. These data confirm that Laurentian and global patterns are in broad agreement: collections from eastern Avalonia, Armorica, Baltica, and South China indicate shelf trilobite alpha diversity as high or higher than those of Laurentia. The apparent stability of species alpha diversity is particularly surprising in view of the long-term Ordovician-Silurian decline in global taxonomic richness of trilobites, which resulted in a total number of genera for the Early Silurian (Wenlock) that was only 40% of the number in the Middle Ordovician (Whiterock). This decline must be a consequence of large scale controls on diversity, such as a reduction in levels of provinciality among trilobites in the Late Ordovician. The results of the analysis affirm the need for a hierarchical approach to the analysis of diversity in the fossil record.

L. Ramskold (1991): Pattern and process in the evolution of the Odontopleuridae (Trilobita); the Selenopeltinae and Ceratocephalinae. -
Transactions of the Royal Society of Edinburgh: Earth Sciences, 82(2): 143-181.

Lars Ramskold and B. D. E. Chatterton (1991): Revision and subdivision of the polyphyletic "Leonaspis" (Trilobita). - Transactions of the Royal Society of Edinburgh: Earth Sciences, 82(4): 333-371.

[Jens]

N. V. Wilmot (1990): Cuticular structure of the agnostine trilobite Homagnostus obesus. - Lethaia, 23(1):87-92.

Antoni Hoffman and Wolf-Ernst Reif (1994): Rudolf Kaufmann's work on iterative evolution in the Upper Cambrian trilobite genus Olenus; a reappraisal. - Palaeontologische Zeitschrift, 68(1-2):71-87.

Torsten Tjernvik (1953): Notes on two new trilobites from the upper Cambrian of Sweden. - Geologiska Foereningen i Stockholm Foerhandlingar, 75(1): 72-76.

Christiana Ribecai and Marco Tongiorgi (1997): Lusatia dramatica, a distinctive new species from the Upper Cambrian of Oland (Sweden). - (in Festschrift for Helen Tappan and Alfred R. Loeblich Jr.), Review of Palaeobotany and Palynology, 98(1-2): 27-32.

Abstract:
A new acritarch species (Lusatia dramatica) is described from uppermost Cambrian beds (Peltura scarabaeoides Trilobite Zone) of the Degerhamn Quarry Road section, southern Oeland, Sweden. The filamentous branches of the well-developed processes of Lusatia dramatica, resemble structures shown by many latest Cambrian diacrodians of the Baltic region.

David L. Bruton (1999): Notes on Brogger's type species of agnostid trilobite genera. - GFF, 121(4): 337-341.