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The paper presents new finds of fossil fauna and flora at the rediscovered locality Krsmol "Deep gorge" ("Hluboká rokle") of the Ploužnice Horizon (Semily Formation, Krkonoše Piedmont Basin). Several metres thick reddish to grey tuffaceous siltstones of this lacustrine horizon contain 10 centimetres thick layer of grey, hard, siltstones with good fissility, containing one to two thin layers enriched in isolated osteological fragments of vertebrates at the base. Scales and teeth of actinopterygians, scales and fragments of the pectoral girdle of acanthodians are common, and teeth of chondrichthyans can be occasionally found. Rare scales of actinopterygians, isolated insect wings and sporadic plant remains are also present in the overlying reddish-purple siltstone. The newly found fauna in Krsmol extends the existing knowledge based on the old collections and coincides in species with the findings at other sites of the Ploužnice Horizon. From the biostratigraphic point of view, the findings of scales of actinopterygian fish Sphaerolepis kounoviensis, which is an important representative of the biozone corresponding to the uppermost Carboniferous shark teeth and especially the wings of the insect Sysciophlebia rubida of the family Spiloblattinidae are significant, on the basis of which the strata can be classified as Stefan B/C (Kasimovian/Gzhelian) similarly to the strata at other sites of the Ploužnice Horizon. [ABSTRACT FROM AUTHOR]

About 100-1 50 m thick intercalation of dark micaceous siltstone to black clayey shale can be distinguished in the middle part of the Letná Formation (Upper Ordovician, Lower Sandbian) at several localities in the NW and NE parts of the Prague Basin. Sandstone and greywacke, dominant elsewhere in this formation, form only a subordinate part of the sequence. In the NW belt of the Letná Formation, N of the Prague Fault (see Fig. 1C), this thick intercalation has been previously known from Bulovka -Bílá Skála Rock and from Rudolfova Štola Gallery (Rohlich 1956, 1960; Mikuláš 1994). A comparable, slightly thinner, and locally discontinuous intercalation of dark siltstone and black clayey shale was described also in the middle belt of the Letná Formation, S. of the Prague Fault (see Fig. 1C) by Rohlich (1956, 1960); such lithology is known from the Praha - Žižkov, Kyje and Malešice areas. An equivalent of this interlayer was documented by Budil (1996) in the middle part of the Letná Formation from the Černý Most area. No such interlayer of dark, fine-grained sediments has been reported from the southern belt of the Letná Formation (Fig. 1C), most probably because of its much poorer exploration. New borehole documentation at Praha - Střešovice extends our knowledge on the above - discussed dark siltstone and claystone intercalation in the NW belt of the Letná Formation. In two boreholes (HJ 11 and HJ 16), more than 60 m thick sequence of dark, fine-grained sediments has been documented in the middle part of the Letná Formation. The presence of these sediments was confirmed also by the study of archive data - previous geotechnical documentation of this area. The archive data documented the presence of a second, thinner and rather lenslike body of dark, fine-grained sediments which can be traced in the lower third of the Letná Formation in the Střešovice area. It is suggested that the sedimentation of relatively thick sequences of dark siltstones and shales reflects short-time periods of decrease in the input of clastic material. Alternatively, it could correspond to a partial, synsedimentary tectonic-related deepening of respective parts of the sedimentary basin. Locally bioturbated black siltstone and shale sequence is barren of benthos and contains only rare remains of indeterminable linguliformean brachiopods. It is supposed that such association corresponds to the Paterula Community of Havlíček (1982), so far only poorly documented from the Letná Formation (Van Roy et al. 2021). [ABSTRACT FROM AUTHOR]

The Upper Ordovician sediments of the Bohdalec (Katian) and lower layers of the Králův Dvůr (Katian) formations were exposed at Dolní Počernice, a suburb in the eastern part of Prague, during driving of an underground conduit along the Nad Rybníkem Street at the turn of 2017 to 2018. The full sequence of sediments was not accessible and the investigation was restricted to the material deposited on a nearby dump where it was concentrated mainly on the dark grey siltstone and shale of the Bohdalec Formation, which allowed detailed study of this formation exposed only at a few lasting outcrops. Large amount of these rocks (about 3.000 kg) were transported to the storage place of National Museum at Horní Počernice during several months, and subsequently studied in detail. These occasional outcrops provided a poorly diversified assemblage of invertebrates, characterized by dominance of graptolites and trilobites. This paper focuses on the most common trilobite species Onnia superba (Bancroft, 1929). The studied taxon occurred here mainly as meraspid shields, both cephalic and pygidial or as completely preserved (mostly juvenile) specimens. Several hundreds of collected trilobites and their accumulations document almost a complete ontogenetic development from the degree M1 up to the late holaspid specimens (no protaspid specimens were found). Some meraspid trilobites show marks of disarticulation or typical exuviation patterns, and they can be considered as disintegrated exuviae. On the other hand, outstretched or enrolled complete meraspid specimens or their accumulations (regarded as carcasses) were preserved with articulated free cheeks including long genal spines. These specimens and accumulations provide valuable taphonomical and paleoecological information, whose additional interpretations (together with the study of Onnia superba ontogeny) will be a subject of next investigation. [ABSTRACT FROM AUTHOR]