4. Abundance of 'Orsten' or 'Orsten'-like fossils

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

Our Swedish material comprises about 1,500 – 2,000 specimens of arthropods with preserved softparts (ventral cuticular details, e.g. their limbs) and something between 50,000 and 100,000 specimens of the so-called phosphatocopines. More than 2,000 of the these tiny bivalved crustaceans are preseved with remains of their soft parts.

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

1. Among these 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.

A summarising paper by Andreas Maas will hopefully appear still this year in a book by Andreas Schmidt-Rhaesa, Hamburg.

2. The other set contains the arthropods. The variety extends from "stem arthropods" such as the lobopodian Orstenotubulus, a tardigrade (not published yet), several pentastomids (several papers published, the last in 2011), and euarthropods such as a chelicerate larva with pantopod affinities (Klausmuelleria), immature stages of Agnostus pisiformis to numerous species of Crustacea. Strikingly, these represent several different evolutionary levels, which helped us to establish a detailed phylogeny of Crusatcea.

Several of these species were preserved with larval stages, so giving a detailed view of the evolution of ontogenies of Crusatcea in the Cambrian.

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 of all Cambrian lagerstaetten, ranging from the Lower Cambrian to the lower Ordovician.

3. As mentioned already above, 'Orsten' residues also contain so-called small shellies and, moreover, phosphatised and non-phosphatized fragments, many of unclear affinities. These odds and ends are currently being investigated by Christopher Castellani from our team, incl. remains of brachiopods and sponge spicules (paper just submitted by Christopher). Christopher also has just finished a paper on the first echinoderm larva from the Cambrian, which however was rejected by Nature, and is writing a paper on cyanobacteria. We do hope to receive, by his studies, a much better overview of the biodiversity in the Middle to later Cambrian alum shale sea as known before.

4. 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, his colleague Per Ahlberg from Lund, Sweden, and the two new members Mats Eriksson and Frederik Terfelt.

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 Donoghue's papers) and from Australia (found by Dieter Waloszek 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. Please ask us for it.
   
   Remarks: The second find of type A larvae is from Australia – and here remarkably from the Middle Cambrian (Walossek et al. 1993).