4. Abundance of 'Orsten' fossils

At present, we have accumulated data mainly from' Orsten' localities in Sweden (Västergötland and Öland) and/or from taxa, which we investigated in Bonn and Ulm. In the future, we hope to present also more information from other 'Orsten' fossils and according lagerstaetten around the World investigated by our C.O.R.E.-Group collaborators, for example, Comley, UK, or China.

Our Swedish material comprises about 1,500 – 2,000 arthropod specimens with preserved softparts and something between 50,000 and 100,000 specimens of phosphatocopines, more than 2,000 of them with remains of soft parts. Soft parts here means preservation of cuticular structures softer than just the tergal sclerites, i.e. ventral details such as eyes and appendages, body proper etc.

Taking all data together, the estimated number of species in 'Orsten'-type preservation has increased to roughly 100, 70 species being from Sweden. Only about one half of the number = 45 of all Orsten fossil species have been described taxonomically (named) so far.

1. Among the taxa, 20 species belong to the taxon Nemathelminthes (round worms). Remarkably, all are from Australia: 1 small cycloneuralian (published), a few priapulid-like loricae (published), 2 specimens of a new species of Markuelia (published; more Markuelia taxa from other parts of the World to be added), and several so-called palaeoscolecids, worm-like nemathelminths of most likely scalidophroan affinities, of which only the scleritic skin was found so far in Orsten type preservation (e.g., in Müller & Hinz 1993), but these are also known from two-dimensionally preserved specimens in the Chinese Chengjiang fauna. Nemathelminth fossils and Markuelia are also a research topic of our CORE member Phil Donoghue.

2. The other set are arthropods: stem arthropods such as the lobopodian Orstenotubulus, a tardigrade (not published yet), several pentastomids (published and close to submission), and euarthropods such as a chelicerate larva with pantopod affinities (Klausmuelleria), young of Agnostus pisiformis and numerous crustaceans. Strikingly, these are representatives of different evolutionary levels, several of hem with larval stages preserved.

Accordingly, the 'Orsten' comprises, not taken the many non-phosphatized or macroscopic taxa into account, about as many species as the faunal associations known as Chengjiang and Burgess, but, admittedly, only from two major taxa (which implies even more animals around because surely also others co-existed with the preserved ones). Yet, the Orsten has the longest timespan ranging from the Lower Cambrian to the lower Ordovician.

As mentioned already above, 'Orsten' residues als contain several so-called small shellies and non-phosphatized fragments, such as brachiopods and sponge spicules. Lastly there are several macrofauna components preserved in 'Orsten' rocks and the surrounding alum shales, such as trilobites and agnostids. Trilobites from the Swedisch alum shales are continuously being investigated by our CORE member Euan Clarkson from Edinburgh and his colleague Per Ahlberg from Lund, Sweden. 'Orsten' "odds and ends" are the current study objects of Christopher Castellani for his dissertation (with a DFG-funded project).

5. Studies of 'Orsten'-type fossils outside of our C.O.R.E. group

Until now, few workers have grabbed this exceptional chance to successfully discover similar or the same kinds of organisms. We are happy to say that several colleagues like Phil Donoghue, Dong Xiping and Zhang Xiguang have become CORE members in the meantime.

1. Xiao Shuhai, Zhang Yun & Knoll, Andrew H. (1998). Three-dimensional preservation of algae and animal embryos in a Neoproterozoic phosphorite. Nature 391, 553–558.
   Phosphorites of the late Neoproterozoic (570 ±20 MyrBP) Doushantuo Formation, southern China, preserve an exceptional record of multicellular life from just before the Ediacaran radiation of macroscopic animals. Abundant thalli with cellular structures preserved in the three-dimensional detail show that latest-Proterozoic algae already possessed many of the anatomical and reproductive features seen in the modern marine flora.
   
   
2. Bengtson, Stefan & Zhao Yue (1997). Fossilized Metazoan Embryos from the Earliest Cambrian. Science 277, 1645–1648.
   Small globular fossils known as Olivooides and Markuelia from basal Cambrian rocks in China and Siberia, respectively, contain directly developing embryos of metazoans. Fossilization is due to early diagenetic phosphatization. A nearly full developmental sequence of Olivooides can be observed, from late embryonic stages still within an egg membrane, to hatched specimens belonging to several ontogenetic stages. Earlier cleavage stages also occur, but cannot be assigned to a taxon. Olivooides shows similarities to coronate scyphozoans and to their probable Palaeozoic representatives, the conulariids. Markuelia eggs contain looped embryos of a segmented worm with short, conical processes covering the body.
   
   Remarks: Markuelia specimens have also been reported from other localities, such as from north America (mentioned in one of Phil's papers) and from Australia (found by Dieter in 1986).
   
   
3. Roy, Kaustuv & Fåhræus, Lars E. (1989). Tremadocian (Early Ordovician) nauplius-like larvae from the Middle Arm Point Formation, Bay of Islands, western Newfoundland. Canadian Journal of Earth Sciences 26, 1802–1806. This is the exciting and first description of larvae of our type A outside the Baltoscandian Shield (see Müller & Walossek 1986; Walossek & Müller 1989). The material has been reworked, so was most likely Upper Cambrian, not Lower Ordovician. Yet, Type A larvae are exceptional because they occurred from zone 1 to 5/6 in the old stratigraphic system. Xerox on request, but we will also produce a PDF as soon as possible.
   
   Remarks: The second find of type A larvae is from Australia – and here remarkably from the Middle Cambrian (Walossek et al. 1993).