91

NEWS

© Blackwell Publishing Ltd, The Geologists’ Association & The Geological Society of London, Geology Today, Vol. 28, No. 3, May–June 2012

News featureThe ‘Polish Solnhofen’: a long-awaited alternative?

Adrian Kin1,2, Błażej Błażejowski2,3 & Marcin Binkowski4

1Jagiellonian University,

Kraków, Poland

amonit79@tlen.pl 2’Phacops’ Association of

Friends of Geosciences 3Institute of Paleobiology,

PAS, Warszawa, Poland

bblazej@twarda.pan.pl 4Institute of Computer

Science, University of

Silesia, Poland

marcin.binkowski@us.edu.

pl

Here we briefly report on the discovery of a new Fossil-Lagerstätte locality, Owadów-Brzezinki quarry (central Poland), which exposes Late Jurassic (Late Tithonian) carbonate sediments with an extremely fossiliferous horizon of lithographic-type limestones. Numerous specimens of horseshoe crabs were found in association with an enormously rich assemblage of the soft-shelled bivalves Corbulomima obscura and Mesosaccella sp., the remains of various fishes and marine reptiles, rare ammonites, crustaceans, land insects and pterosaurs. The uniqueness of this new locality lies in its very close stratigraphical relationship to one of the most famous Fossil-Lagerstätte localities in the world—Solnhofen, in southern Germany, with approximately 2 Ma separating them. Marine and terrestrial creatures lived and died during the Late Jurassic both at Solnhofen (Hybonotum Zone) and in another area (Owadów-Brzezinki quarry, Zarajskensis Subzone), under closely related environmental conditions. The small palaeogeographical distance separating these two locations enables, for the first time, an effective palaeobiological test of the pace of evolutionary speciation amongst different groups of organisms.

Our discovery was in the Tithonian limestones of the Owadów-Brzezinki quarry, located about 18 km south-east of Tomaszów Mazowiecki (Central Poland, Figs 1, 2). Here Late Tithonian (= middle Volgian) carbonate sediments are exposed in a small working quarry belonging to the Nordkalk Company (Sławno). The main results of our work will appear in the jour-nal Lethaia; this article reports on the findings for a wider audience.

In the Owadów-Brzezinki quarry, the exposed sedi-mentary sequence belongs to the Kcynia Formation, and can be divided into three sucessive units: I, II and III. Biostratigraphically, the carbonates belong to the Scythicus Zone, Zarajskensis Subzone, in the upper-most part of the Regularis Horizon (through almost the entire Zarajskensis Horizon). The lowermost unit I comprises, initially, yellowish thin-bedded marly limestones that pass gradually upwards into massive fine-grained limestones (~6.6 m total thickness), with indistinctive lamination, which form a few beds of 40–80 cm thickness. The overlying unit (II) is repre-

sented by thinly-bedded, fine-grained limestones with occasional distinctive parallel lamination and mass occurrence of polychaete tubes in a thin horizon.

Fig. 1. Locality map of ‘Polish Solnhofen’ = Owadów-Brzezinki quarry (central Poland). Key: 1, Marine sediments, not studued in detail. 2, Shallow water limestone. 3, Siliclastic, fine-grained sediments.

92

NEWS

© Blackwell Publishing Ltd, The Geologists’ Association & The Geological Society of London, Geology Today, Vol. 28, No. 3, May–June 2012

The uppermost unit (III) is highly fossiliferous, with a horizon of finely bedded fine-grained limestones at its base (also called the ‘Corbulomima horizon’), domi-nated by small opportunistic bivalve Corbulomima ob-scura and somewhat less numerous Mesosaccella sp.

(Fig. 3). Other fossils are much rarer (i.e. in com-parison with corbulid bivalves) and represented by well-preserved moulds of ammonites ?Zaraiskites ex gr. zarajskensis (Fig. 4), horseshoe crabs Limulus sp. n. and Crenatolimulus sp. n. (Fig. 5) plus other marine and land arthropods (including decapods, beetles and dragonflies). Moreover, quite rich and well-preserved teeth and bones (much rarer articulated skeletons) of different vertebrates also occur in the ‘Corbulomima horizon’ (Figs 7–9). One of the most interesting re-cent finds is the remains of an aquatic sphenodontian (Fig. 9, and see the Supporting Information). Tapho-nomical evidence from the macrofossil assemblage of the fossiliferous ‘Corbulomima horizon’ shows that the unit is a Konzentrat-Lagerstätte. However, a rare find of an almost completely preserved organism (e.g. limulids and fish) within the fossiliferous ‘Corbulomima horizon’ suggests, that locally, this horizon could also represent a transitional facies between a Konzentrat- and Konservat-Lagerstätte. The ‘Corbulomima horizon’

Fig. 2. Panoramic view of the highest level of exploitation in Owadów-Brzezinki quarry (i.e. unit III and most fossiliferous ‘Corbulomima horizon’ occurring in the middle of the quarry wall).

Fig. 3. Soft-shelled bivalves: a. Lithographic limestone slab with Corbulomima obscura and Mesosaccella sp. (scale bar = 10 mm); b. Mesosaccella sp. (scale bar = 60 mm).

Fig. 4. Ammonite ?Zaraiskites ex gr. zarajskensis (scale bar = 10 mm).

Fig. 5. Horseshoe crab Crenatolimulus sp. n. (scale bar = 10 mm).

(a)

(b)

93

NEWS

© Blackwell Publishing Ltd, The Geologists’ Association & The Geological Society of London, Geology Today, Vol. 28, No. 3, May–June 2012

passes upwards into thin- to medium-bedded lime-stones with very rare corbulid bivalves, and almost no other macrofossils. In general, the sedimentary and palaeontological evidence from units I, II and III documents the change from an offshore to nearshore, perhaps lagoonal, setting.

There are some obvious similarities between Sol-nhofen and the Owadów-Brzezinki quarry. First, a similar range of macrofauna has been identified in both localities. Interestingly, these similarities are confirmed among both marine and terrestrial organ-isms and allows us to begin comparative palaeonto-logical studies at a previously unattainable level of taxonomic resolution. An example showing the great importance of these comparative studies may be the identification of a new species of dragonfly, belonging to the family Eumorbaeschnidae, a family previously known only from the Solnhofen area. Preliminary studies already conducted on other organisms from the ‘Corbulomima horizon’ present similarly encour-aging results. This fact allows us to conclude that the Owadów-Brzezinki quarry will carry the status of a new outstanding ‘open window’ into the evolu-tion of living organisms, especially as it represents the first closely-aged palaeontological ‘alternative’ to Solnhofen, one of the most famous Fossil-Lagerstätte in the world.

In both localities, whole exceptionally well-pre-served fossils occur in micritic limestones of litho-

Fig. 6. Most of the ‘Polish Solnhofen’ working group (from the left): Leslie Marshall, Prof. Jim D. Marshall, Julia Gruszczyńska and Prof. Michał Gruszczyński.

Fig. 7. Disarticulated pycodontid fish skeleton, exposed in situ at the bottom of the quarry.

Fig. 8. Dentary bone of actinopterygian fish Caturus sp.: a. just after discovery; b. reconstruction of 3-D ‘virtual fossils’—the same specimen after digital processing and analysis of tomographic data (scale bar = 10 mm).

graphic-type (i.e. very pure, well-bedded limestones also known as platy limestones or plattenkalk), formed in a similar—lagoonal—depositional environ-ment. In the case of Solnhofen, which during the Late Jurassic was located at the northern margin of the Tethys, the carbonates were deposited in a relatively deep lagoon with only slightly restricted access to the open ocean (i.e. a natural barrier constituted of algal-sponge reefs and small, isolated coral reefs). In contrast, the eastern part of the epicontinental sea in the Owadów-Brzezinki area was extremely shal-low and the lagoon was probably almost completely isolated from open marine conditions (a periodic con-nection with the open sea indicated by a very rare occurrence of ammonites).

An innovative part of our research into the ‘Polish Solnhofen’ and its exceptionally well-preserved fossils is the application of X-ray microcomputed tomogra-phy (XMT) as a non-invasive tool for detailed research on marine and terrestrial fossil faunas. This method provides excellent results for the high-resolution quantitative volumetric investigation of diverse sam-ples (Figs 8b, 9b, see also Supporting information). One of the most effective methods for digital process-ing and analysis of tomographic data is the construc-tion of isosurface-based ‘virtual fossils’, which can be manipulated and dissected interactively. To generate 3-D models the XMT technique was applied, which is based on differences in attenuation of the X-ray beam propagating through a solid object. The background was removed from the images by thresholding (com-pare Figs 8 and 9). Further information will be pub-lished in our forthcoming paper in Lethaia.

(a)

(b)

94

NEWS

© Blackwell Publishing Ltd, The Geologists’ Association & The Geological Society of London, Geology Today, Vol. 28, No. 3, May–June 2012

Acknowledgements

We would like to thank Kasia Kin for assistance and support during the fieldwork and Sebastian Nicpon for making the 3D animation of the ‘virtual fossils’. We wish to thank Robert Siuda (Managing Direc-tor) and Cezary Błaszczyk (Plant Manager) for their invaluable support and in enabling research in the Owadów-Brzezinki quarry (Nordkalk Company). We also express our thanks to all the members of the ‘Phacops’ Association for their help in collecting the fossils.

Suggestions for further reading

Błażejowski B., Binkowski M., Bitner M.A. & Gieszcz P. 2011. X-ray microtomography (XMT) of fossil brachiopod shell interior for taxonomy. Acta Palae-ontologica Polonica, v.56, pp.427–428.

Keupp, H., Koch, R., Schweigert, T. & Viohl, G. 2007. Geological history of the Southern Franconian Alb – the area of the Solnhofen Lithographic Lime-stone. Neues Jahrbuch für Geologie und Palëontologie, Abhandlungen, v.245, pp.3–21.

Kin, A., Gruszczyński M., Martill D., Marshall J.D. & Błażejowski B. 2012. The paleoenvironment and taphonomy of a Late Jurassic (Late Tithonian) La-gerstädtte from central Poland. Lethaia, in press.

Munnecke, A., Westphal, H. & Kolbl-Ebert, M. 2008. Diagenesis of plattenkalk: examples from the Sol-nhofen area (Upper Jurassic, S-Germany). Sedimen-tology v.55, pp.1931–1946.

Seilacher, A. 1970. Begriff und Bedeutung der Fossil-Lagerstätten. Neues Jahrbuch fur Geologie und Paläon-tologie, v.LXII, pp.34–39.

Supporting Information

Additional Supporting Information may be found in the online version of this article:

http://www.phacops.pl/pl/news/273,pleuro The video show Visualization (3-D model) of the Pleu-rosaurus sp. mandible from ‘Corbulomima horizon’ at Owadów-Brzezinki quarry, central Poland.

Please note: Wiley-Blackwell are not responsible for the content or functionality of any supplementary materials supplied by the authors. Any queries (other than missing material) should be directed to the cor-responding author for the article.

Fig. 9. Mandible of aquatic sphenodontian Pleurosaurus sp.: a. specimen in piece of lithographic limestone; b. 3-D model of ‘virtual fossils’—a different view of the same specimen (visible from the inside) after digital processing and analysis of tomographic data (both scale bars = 10 mm).

(a)

(b)