Petr Kraft

Shallow-Water Occurrence of Wiwaxia in the Middle Cambrian of the Barrandian Area, Czech Republic

Isolated sclerites of the genus Wiwaxia are reported from shale interlayers in lower levels of middle Cambrian (unnamed 3rd Series of Cambrian) Buchava Formation in the Skryje-Týřovice Basin in the Czech Republic interpreted as shallow-water sediments. Geographic distribution of Wiwaxia indicates latitudinal control as all occurrences are obviously restricted to tropical belt.

MANITOUSCOLEX, A NEW PALAEOSCOLECIDAN GENUS FROM THE LOWER ORDOVICIAN OF COLORADO

Palaeoscolecidans represent an extinct class of vermiform organisms with a prominent annulation ranging from the Lower Cambrian to the Upper Silurian. Since the first descriptions in the 1950s, they have been attributed to different groups, but recently they have been linked to the priapulids (Conway Morris, 1997). Palaeoscolecids are mainly considered to represent members of Ecdysozoa. Their position within this clade is still under discussion, but cladistic analyses indicate that they are either close relatives of nematomorphs (Hou and Bergstrom, 1994) or part of an extinct sister clade to the priapulids (Wills, 1998; Dong et al., 2004). The outer cuticle of palaeoscolecidan segments possesses microelements mineralized by calcium phosphate, which are often found isolated in the conodont collections obtained from carbonates after acid treatment. Kraft and Mergl (1989), van den Boogaard (1989b), Hinz et al. (1990), and Muller and Hinz-Schallreuter (1993) clearly showed the evidence that these isolated sclerites originate from certain palaeoscolecidan taxa. The specimens documented in this paper represent such fragmented material from the Manitou Formation of west-central Colorado. Extensive taxonomic and morphologic reviews of the palaeoscolecidans were provided by Muller and Hinz-Schallreuter (1993), Conway Morris (1997), Wrona and Hamdi (2001), and Ivantsov and Wrona (2004). Palaeoscolecidans have been reported from different paleogeographic areas in the Ordovician (Kraft and Lehnert, 2004). In general, this group is widespread from tropical to cool water environments. Lower Ordovician whole body fossils have been published only from peri-Gondwana (e.g., Whittard, 1953; Kraft and Mergl, 1989), and there is limited information from tropical areas treating only isolated microremains (fragments and tubercles). In this time interval the data from tropical continents are restricted to Laurentia (e.g., Ethington and Clark, 1981; Repetski, 1981). The studied material was recovered from a section at Cave of …

A possible hydroid from the Lower and Middle Ordovician of Bohemia

A new genus Webbyites from the Lower and Middle Ordovician of Bohemia is described. Its planar, feather-like benthic colonies (or their parts) display possible hydrozoan affinites. Webbyites is interpreted as an inhabitant of the littoral and sublittoral environment, with high energy, oscillating to current zones.

Dynamics of placoderm distribution in the Prague Basin (Czech Republic)

The occurrence of placoderms in the Prague Basin (Bohemian Massif; Czech Republic) shows a very unsteady distribution in space and time. The most abundant specimens are in the Lochkovian and, through decrease in the Pragian, they become rare towards the Givetian. The primitive acanthothoracids dominating in the Lochkovian and Pragian are completely replaced by arthrodires at the beginning of the Emsian. All placoderms in the Prague Basin, without any regard to their dimensions, had smooth jaws which is a proof of their non-predatory feeding habit. Although placoderm diversity is generally considered to reflect the Devonian nekton revolution, the abundance of these vertebrates in the Prague Basin displays a decrease, i.e. an inverse tendency to the global one.

Das untere Ordovicium bei Rokycany, Tschechische Republik

Das untere Ordovicium (Arenig bis Dobrotiva) von Rokycany in West-Bohmen liegt im Westteil des Prager Beckens (Abb. 1), einer schmalen Synkline, die sich in SW-NE-Richtung zwischen Plzeň und der ostlichen Umgebung von Praha erstreckt (Abb. 1). Diese Struktur enthalt eine vollstandige Schichtenfolge vom Unter-Ordovicium (Tremadoc) bis zum Mittel-Devon (Givet). Der grosste Teil des Beckens ist mit ordovicischen Ablagerungen gefullt; Silur und Devon sind als Abtragungsreste auf den mittleren Teil des Beckens beschrankt (Abb. 3).

Index of Fossiliferous Localities of the Olešná Member, Klabava Formation (Lower Ordovician of the Prague Basin, Czech Republic)

Abstract Thirty-two fossiliferous localities of the Olešná Member, a distinct unit of the Klabava Formation, are described. As we are able to find they represent all fossil sites of this unit ever been mentioned in publications. Fossil taxa from relevant papers are summarized and the historical names used for the localities are listed. Updated lists of fauna are compiled for each locality; based on them an overall list for the member is completed.

Trepostome bryozoans from the Zahořany Formation (Upper Ordovician) of Loděnice, Prague Basin, Czech Republic

Three trepostome bryozoan species are described from the Upper Ordovician Zahořany Formation of Loděnice, Prague Basin, Czech Republic. One genus is new—Lodenicella gen. nov. One species is described in open nomenclature. The described fauna contains ramose colonies or ramose branched projections from encrusting tubular-shaped colonies which inhabited shallow environment with moderate wave energy and significant influx of clastic material.KurzfassungDrei Arten der trepostomen Bryozoen werden aus der oberordovizischen Zahořany Formation von Loděnice, Prager Becken, Tschechische Republik, beschrieben. Eine Gattung ist neu - Lodenicella gen. nov. Eine Art wird in offener Nomenklatur geführt. Die beschriebene Fauna besteht aus ramosen Kolonien oder ramosen ästigen Auswüchsen von inkrustierenden rohrförmigen Kolonien, welche ein seichtes Milieu mit moderater Wellenenergie und erheblichem Eintrag von klastischem Material bewohnt haben.

Trepostome bryozoans from the Zaho??any Formation (Upper Ordovician) of Lod??nice, Prague Basin, Czech Republic

Three trepostome bryozoan species are described from the Upper Ordovician Zahořany Formation of Loděnice, Prague Basin, Czech Republic. One genus is new—Lodenicella gen. nov. One species is described in open nomenclature. The described fauna contains ramose colonies or ramose branched projections from encrusting tubular-shaped colonies which inhabited shallow environment with moderate wave energy and significant influx of clastic material.KurzfassungDrei Arten der trepostomen Bryozoen werden aus der oberordovizischen Zahořany Formation von Loděnice, Prager Becken, Tschechische Republik, beschrieben. Eine Gattung ist neu - Lodenicella gen. nov. Eine Art wird in offener Nomenklatur geführt. Die beschriebene Fauna besteht aus ramosen Kolonien oder ramosen ästigen Auswüchsen von inkrustierenden rohrförmigen Kolonien, welche ein seichtes Milieu mit moderater Wellenenergie und erheblichem Eintrag von klastischem Material bewohnt haben.