Research
The research of the Micropalaeontology II Section emphasizes conodont taxonomy, conodont chronology and the reproduction of stratigraphical data for Devonian time. Rock sequences are dated by microfossils, their data are arranged chronologically and correlated, i.e. extra-regionally compared with earth layers of the same ages. For that purpose, conodont forms are differentiated (=taxonomy) and evolution of their morphological changes is described (=phylogeny).
Their potency as time markers is examined (=guide fossils, stratigraphy) as well as their utility for the spatial distinction of marine areas (=facieology, palaeoecology, palaeogeography).
Conodont chronology of Devonian time in particular provides possibility of very fine resolution dating, which is not evenapproximately reached by other fossils. Since conodont guide fossils are recognizable and applicable in Devonian layers world-wide, the official international subdivision of the Devonian into stages was recently defined by means of certain conodonts. Each of these conodonts indicates a calibration point per base of a stage, a so-called ‘Global Stratotype Section and Point (GSSP)’, which was selected by the International Subcommission on Devonian Stratigraphy of UNESCO. The Micropalaeontology II Section participated in the proposals of the index conodonts for four of six Devonian stages. These were for the Lower Devonian ‘Pragian stage’ (its GSSP was institutionalized in 1988) and ‘Emsian Stage’ (1989) as well as the Middle Devonian ‘Eifelian Stage’ (1982) and ‘Givetian Stage’ (1992).
The base of the Eifelian Stage, which also defines the beginning of the Middle Devonian, has traditionally been within the interests of Senckenberg stratigraphical research. Thus, a research trench near the village of Schönecken-Wetteldorf in the Eifel Mountains was initiated by the former Senckenberg director Rudolf Richter in 1937. And in the 70's, because of the international programme on defining the GSSP, Senckenberg researchers opened this trench again, in order e.g. to research the conodont contents. Thus, it could be institutionalized as a GSSP in 1982, and the Eifelian Stage remained as internationally applicable stage, with the Eifel Mountains as type area of the stage
The international calibration point GSSP (Global Stratotype Section and Point) for the beginning of both, of the Middle Devonian and of the Eifelian Stage, which represents the first stage of the Middle Devonian. The GSSP is situated at the margin of the village Schönecken-Wetteldorf in the Eifel Mountains. It is protected by a hut erected over the section.
After the international definitions of stage subdivisions, a substantial task of the stratigraphical commissions may consist of publishing the status quo of stratigraphical knowledge of respective boundary sequences. The Head of the Micropalaeontology II Section initiated an important step in this direction by the publication of a ‘Devonian Bibliography’ (starting from 1995) and by a ‘Devonian Correlation Table (DCT)’ (starting from 1996). Because of their annual supplements, both have become established institutions of Devonian research. The DCT is formatted within a fixed framework, the scale at the left table margin functions in practice as an actual standard scale for stratigraphical data, and is called ‘time ruler’. The time ruler measures data by their heights in the correlation table, and thus time is measured in centimetre/millimetre (DCT cm) and not in millions years (m. y.). As a linear partitioned scale the time ruler is a provisional replacement for the million-year scale, which is treated now as a subordinate nonlinear scale. The time ruler has priority, because almost every millimetre of the time ruler is defined by all the DCT table data at the same height, whereas the million-year scale is only proven by relatively few points with radiometric data. Moreover, the question about time-linear proportions of time periods results from the DCT, e.g. the question of how longer a conodont zone may have lasted than another one. Mainly, however, the question about the certainty and/or uncertainty of data results from cm-mm-exact arrangment of data in the DCT, e.g. the question of how thickly a boundary layer has to be drawn into the DCT. How gradual is the transition in the field? How exact are the guide fossils responsible for defining a boundary or an event?
The DCT thus integrates a broad spectrum of substantial data in one reproducable system. All data are translated by means of time ruler units into a language, which is immediately understood by everyone without particular geological previous knowledge.