Fossil biota of the Skały Formation

A special issue of the Annales Societatis Geologorum Poloniae, guest edited by Adam T. Halamski and entitled „Middle Devonian biota and environments of the Łysogóry Region (Poland)”, has been published. Six papers in this special issue are authored by 27 scientists from four countries (including three persons from IPal); generalities about this project can be found in the preface.

We investigated the biota (all living organisms) of the Skały Formation, a stratigraphic unit corresponding to sediments formed in the Devonian period, more exactly about 386–382 million years ago. Lithological, geochemical, and palaeontological data collected at Miłoszów (Holy Cross Mts., Poland) served for reconstructing a Middle Devonian ecosystem. 200 species of marine organisms are recorded, among which brachiopods with 68 species are the most diversified, followed by echinoderms and bryozoans. For the first time a detailed palaeoecological reconstruction of one of the most famous localities in Poland, the so-called brachiopod shale at Skały, has been presented. We explored the succession of communities, or, in other words, we showed which brachiopod species had genuinely co-existed the sea located in the area of the present-day Holy Cross Mountains, and which species had followed one another.
We concluded that the exceptionally rich biota of the Skały Formation corresponds to a period of particularly favourable conditions for marine organisms between the so-called Kačák Event about 386 million years ago and the Taghanic Event about 381 million years ago.

Illustration: A pictorial reconstruction of the Middle Devonian (Givetian) seafloor at Miłoszów (compare Halamski et al., 2022, fig. 27) with small patch reefs in the shallower part and a brachiopod meadow in the deeper part (drawing by Bogusław Waksmundzki). The photographs show selected inhabitants of the Miłoszów ecosystems. Top row: left to right rugosan coral Thamnophyllum (cross-section), stem element (columnal) of an unidentified crinoid (see lily), spicule of an octactinellid sponge, and an anal tooth of the holothurian (see cucumber) Devonothyonites; not to scale (compare Halamski et al., 2022, figs 12, 13, 23, 24). Bottom row: left to right foraminifer Semitextularia, brachiopod Pentamerella, ostracod Kozlowskiella, trilobite Hypsipariops (enlargement of an eye), and a skeletal element (goniodont) of an unidentified ophiocistoid (extinct class of echinoderms); not to scale (compare Halamski et al., 2022, figs 11, 19 20, 22, 23).

Publication: Halamski, A.T. 2022. Middle Devonian biota and environments of the Łysogóry Region (Poland): Introduction. Annales Societatis Geologorum Poloniae, 92 (4): 317–321.

Halamski, A.T., Baliński, A., Racki, G., Amler, M.R.W., Basse, M., Denayer, J., Dubicka, Z., Filipiak, P., Kondas, M., Krawczyński, W., Mieszkowski, R., Narkiewicz, K., Olempska, E., Wrzołek, T., Wyse
Jackson, P.N., Zapalski, M.K., Zatoń, M. & Kozłowski, W., 2022. The pre-Taghanic (Givetian, Middle Devonian) ecosystems of Miłoszów (Holy Cross Mts, Poland). Annales Societatis Geologorum Poloniae, 92 (4): 323–379.

Racki, G., Wójcik, K., Halamski, A.T. & Narkiewicz, M. 2022. Middle Devonian Skały Formation in the
Holy Cross Mountains (Poland) – formal description and subdivision based on new field data. Annales Societatis Geologorum Poloniae, 92 (4): 425–444.

Woźniak, P., Halamski, A.T. & Racki, G. 2022. Cyclic ecological replacement of brachiopod
assemblages in the top-Eifelian Dobruchna Brachiopod Shale Member (Skały Formation) of the Holy Cross Mountains (Poland). Annales Societatis Geologorum Poloniae, 92 (4): 445–463.