Nove zoopaleontologicke nalezy v plouznickem obzoru (pennsylvan) podkrkonosske panve

The Ploužnice Horizon is a part of the Semily Formation (Stephanian C) of the Krkonoše Piedmont Basin, and is one of the paleontologically and biostratigraphically essential horizons of the Upper Carboniferous. Rich fauna was discovered recently in the Ploužnice Horizon from the newly opened locality of Ploužnice “Small Ravine” (Štamberg et al. 2016). In view of abundant and diverse fauna at this site, the subsequent investigation in the vicinity of the Ploužnice village was focused on similar layers rich in fossils. The attention was focused on the classic locality of Ploužnice “Railroad cut milestone 61.2”, (Fig. 1), first described by Frič (1912) who depicted and described a thin layer of red claystone with fauna as a “bone bed”. Later, isolated scales of actinopterygians were collected at the above site, but the layer described by Frič as a “bone bed” was not found. The extension of bone bed was discovered during the present excavations at the studied locality but it is exposed five meters higher, on a steep slope of the railroad cut. The sequence of strata containing a 15 cm thick fossiliferous bed of red tuffaceous siltstone, including a tiny 5 mm thick layer of bone bed with rich fauna (Fig. 2A), together with the underlying 10 cm thick nodular chert, is identical with the sequence of strata at the locality of Ploužnice „Small Ravine”. These are obviously outcrops of the same layers at both localities. This conclusion is supported by the occurrence of similar fish remains. Sharks (Chondrichthyes Huxley, 1880) are represented by the families Sphenacanthidae Maisey, 1982, and Xenacanthidae Fritsch, 1889. Placoid scales (Fig. 2B) of the family Sphenacantidae are numerous, and are more common than at the Ploužnice “Small Ravine” locality. Teeth of the same family were discovered for the first time in the Krkonoše Piedmont Basin. The teeth crowns consist of the large central cusp and two or three cusps laterally (Figs 2C, D). All cusps have a conspicuous crest converging to the apex of the cusps. These teeth are similar to those of Sphenacanthus carbonarius (Giebel, 1848), described by Soler-Gijón (1997) from the Puertollano Basin, and they are also known from the Saale, Saar, Dunkard and Kladno-Rakovník basins. Xenacanthid sharks are represented by isolated teeth of Orthacanthus sp. only (Figs 2F, G). Isolated scales of acanthodians (Acanthodii Owen, 1846) are the most common fish remains in the studied “bone bed”, and are accompanied by spines from the anterior border of acanthodian fins (Fig. 2A), and by fragments of their pectoral girdle. Actinopterygians (Actinopterygii Cope, 1877) show small sculptured scales and small, sharply pointed teeth, with a distinct acrodentin apex, corresponding to “Elonichthys” sp., described by Štamberg (2016). The group of actinopterygians completes the find of the lower jaw of Sphaerolepis kounoviensis Frič, 1877 with sharply pointed teeth covering the jaw in a brush-like arrangement (Fig. 2E).

References

BLECHA, M. - MARTÍNEK, K. - DRÁBKOVÁ J. - ŠIMŮNEK, Z. - ZAJÍC, J. (1997): Environmental changes at the Carboniferous/Permian boundary and their impact on floral and faunal assemblages of the fossiliferous lacustrine horizons of the Krkonoše Piedmont Basin. Final Report, project GAČR 205/94/0692. - Czech Geol. Survey, Prague.

FRIČ, A. (1912): Studien im Gebiete der Permformation Böhmens. - Arch. naturwiss. Landes-Durchforsch. Böhm. 15, 2, 1-52.

FRITSCH, A. (1888): Fauna der Gaskohle und der Kalksteine der Permformation Böhmens. II/3. - F. Řivnáč, 65-92. Prag.

FRITSCH, A. (1889): Fauna der Gaskohle und der Kalksteine der Permformation Böhmens. II/4. - F. Řivnáč, 93-114. Prag.

OPLUŠTIL, S. - SCHMITZ, M. - KACHLÍK, V. - ŠTAMBERG. S. (2016): Re-assessment of Lithostratigraphy, biostratigraphy, and volcanic activity of the Late Paleozoic intra-Sudetic, Krkonoše-Piedmont and Mnichovo Hradiště basins (Czech Republic) based on new U-Pb CA-ID-TIMS ages. - Bull. Geosci. 91(2), 399-432.View article

OPLUŠTIL, S. - ŠIMŮNEK, Z. - ZAJÍC, J. - MENCL, V. (2013): Climatic and biotic changes around the Carboniferous/Permian boundary recorded in the continental basins of the Czech Republic. - Int. J. Coal Geology, 119, 114-151.View article

PROUZA, V. - TÁSLER, R. (2001): Podkrkonošská pánev. In: Pešek J. et al., ed.: Geologie a ložiska svrchnopaleozoických limnických pánví České republiky, 128-166. - Čes. geol. úst. Praha.

SOLER-GIJÓN, R. (1997): Euselachian sharks from the Late Carboniferous of the Puertollano Basin, Spain: Biostratigraphic and palaeoenvironmental implications. - Modern Geology, 21, 137-169.

ŠTAMBERG, S. (2016): Actinopterygians of the Stephanian sediments of the Krkonoše Piedmont Basin (Bohemian Massif) and their palaeobiogeographic relationship. - Bull. Geosci. 91, 1, 169-186.

ŠTAMBERG, S. - SCHNEIDER, J. W. - WERNEBURG, R. (2016): Fossil fauna and flora of a re-discovered locality in the Late Carboniferous Ploužnice Horizon of the Krkonoše Piedmont Basin, Bohemian Massif. - Fossil Imprint, 72, 3-4, 215-224.View article

ŠTAMBERG, S. - ZAJÍC, J. (2008): Carboniferous and Permian faunas and their occurrence in the limnic basins of the Czech Republic. - 224 str. Museum of Eastern Bohemia. Hradec Králové.

ZAJÍC, J. (2007): Carboniferous Fauna of the Krkonoše Piedmont Basin. - Acta Musei reginaehradec., Sér. A, 32, 11-16.

ZAJÍC, J. (2013): Zoopaleontologie svrchního karbonu. In: STÁRKOVÁ, K. a kol.: Vysvětlivky k základní geologické mapě České republiky 1 : 25 000, 03-431 Lomnice nad Popelkou, 125-127. - Čes. geol. služba, Praha.