New data on Early Cretaceous (Hauterivian-Barremian) heteromorphic ammonites from northern Germany Micheil V. Kakabadze & Philip J. Hoedemaeker Kakabadze, M.V. & Hoedemaeker, Ph.J. New data on Early Cretaceous (Hauterivian-Barremian) hetero- morphic ammonites from northern Germany. Scripta Geologica, 140: 1-168, 86 pls., 12 figs., Leiden, Janu- ary 2010. M.V. Kakabadze, A. Djanelidze Institute of Geology, M. Alexidze St. 1/9, 0193 Tbilisi, Georgia ([email protected]); Ph.J. Hoedemaeker, Nationaal Natuurhistorisch Museum, P.O. Box 9517, NL-2300 RA Leiden, The Netherlands ([email protected]). Key words – heteromorphic ammonites, systematics, Hauterivian, Barremian, stratigraphy, northern Germany, new taxa. The stratigraphic ranges and systematics of heteromorphic ammonites from Lower Cretaceous (Haute- rivian-Barremian) deposits in Lower Saxony, northern Germany, are revised. Nine genera and forty- seven species of the family Ancyloceratidae Gill, 1871, are described. One genus (Fissicostaticeras) and 20 species are new; Emericiceras ressense, E. sornayiforme, E. serpentinum, E. subtilicostatum, E. gotti, E. hanno­ verense, E. kemperi, Crioceratites hastensis, C. subisocostatus, C. vermiformis, Fissicostaticeras claviferum, F. aequicostatoides, F. rarocinctoides, Paracrioceras kleini, Acrioceras (Acrioceras) sarstedtense, A. (A.) crassico­ statum, A. (A.) aegidii, A. (A.) longum, A. (A.) astrictum and Uhligia aegidii. Contents Introduction ................................................................................................................................................................. 1 Stratigraphic framework ...................................................................................................................................... 2 Key to measurements ............................................................................................................................................ 4 Systematic palaeontology ................................................................................................................................... 4 Acknowledgements ............................................................................................................................................. 66 References .................................................................................................................................................................. 66 Introduction In 2002, the Nationaal Natuurhistorisch Museum – Naturalis (NNM) obtained a rich collection of Early Cretaceous ammonites from northern Germany, the collection of Kurt Wiedenroth. The main part of this collection consists of excellently preserved specimens, which have been collected bed by bed from the Valanginian to Barremian of northern Germany. The stratigraphic provenance of these ammonites is well docu- mented by lithological columns of every quarry sampled. Heteromorphic ammonites are especially well represented in the Wiedenroth Collection; it is these ammonites which form the main zonal index fossils for the Boreal Hauterivian and Barremian. The majority of these specimens were collected between 1977 and 1996 when, due to temporary excavations or canal works, Kurt Wiedenroth had the opportunity to meas- ure and draw in detail litho- and biostratigraphical columns, and to collect the fossils from these sections. Examples include the construction of the subways at the Aegidi- entor Square in Hannover; along the Hildesheimerstasse; along the S-Bahn at the Han- nover Airport; along the Mittelland Canal works in the district of Haste; at quarries 2 Kakabadze & Hoedemaeker. New data on heteromorphic ammonites. Scripta Geol., 140 (2010) along the Mittelland Canal near Wilhelmsdorf; at the O. Gott quarry near Sarstedt; the Resse quarry near Hainholz; and the Flemming quarry near Berenbostel. However, the ammonites in the Wiedenroth collection were insufficiently identified until now, most only to the generic level. Von Koenen (1902, 1904, 1908) was the first author to publish systematic descrip- tions of ammonites and elaborate a detailed biostratigraphical subdivision of the Early Cretaceous of northern Germany. These data still have great theoretical and practical significance. Detailed litho- and biostratigraphic descriptions of the most important Lower Cretaceous sections of northern Germany have been published subsequently, but only a relatively small number of ammonites have been described or identified by later authors (Kemper, 1971, 1976, 1992; Immel & Mutterlose, 1980; Mutterlose, 1989, 1995, 1998; Mutterlose & Wiedenroth, 1996; Mutterlose et al., 1997; Mutterlose & Borne- mann, 2002). A monographic study of Early Cretaceous heteromorphic ammonites from this area against the background of a new systematic approach is desirable. In the present paper the systematic position of the Hauterivian and Barremian heteromorphic genera and species is considered. It contains descriptions of new species and of taxa that were in need of reinvestigation. The present collection is undoubtedly of importance for a detailed biostratigraphic subdivision of the Hauterivian to Barremi- an rocks of northern Germany and adjacent areas of The Netherlands, as well as for zonal correlation between the Boreal regions of Europe-North America-Asia and for the Tethyan-Boreal zonal correlation. As the Wiedenroth Collection is representative of the greater part of the Hauterivian and Barremian ammonite fauna of the North Sea basin sensu lato from England to Poland, it also provides a reference for ammonites found in boreholes in the oil-bearing strata of the North Sea. All specimens described are kept in the Nationaal Natuurhistorisch Museum – Nat- uralis, Leiden. The registration numbers are prefixed with RGM, referring to the former Rijksmuseum van Geologie en Mineralogie. Stratigraphic framework The ammonites from the Wiedenroth collection described in this monograph come from the upper Hauterivian and Barremian of the Hannover area. The ammonite zones in this stratigraphic interval are the following: Upper Barremian (which includes the German “middle Barremian”) Parancyloceras bidentatum Zone Simancyloceras stolleyi Zone Paracrioceras rude Zone Emericiceras sparsicosta Zone Ancyloceras innexum Zone Paracrioceras denckmanni Zone Paracrioceras elegans Zone Lower Barremian Fissicostaticeras fissicostatum Zone Fissicostaticeras rarocinctum Zone Kakabadze & Hoedemaeker. New data on heteromorphic ammonites. Scripta Geol., 140 (2010) 3 Upper Hauterivian Simbirkites (Craspedodiscus) discofalcatus Zone Simbirskites (Craspedodiscus) gottschei Zone Simbirskites (Milanowskia) staffi Zone Aegocrioceras beds (correlated with a part of the Simbirskites (Speetoniceras) inversum Zone in England) Most heteromorphic ammonites of the Wiedenroth collection were collected from the staffi Zone, from bed 83 (rarocinctum Zone) in the Gott quarry near Sarstedt, and from beds 6 and 7 (fissicotatumand fissicostatum-elegans zonal boundary, respectively) in the subway of the Aegidientor Square in Hannover. No heteromorphs were collected from the gottschei, innexum and stolleyi zones. The large number of specimens of Aegocrioceras contained in the Wiedenroth Collec- tion have not been studied and will be described elsewhere. The Aegocrioceras beds rep- resent a rather cold phase during the Hauterivian, but, when temperatures rose again, Aegocrioceras gradually disappeared to give way to species of Crioceratites and Simbir­ skites (Kemper et al., 1987). The first specimens of Emericiceras and Crioceratites were collected from bed 44 at quarry 4 along the Mittelland Canal near Wilhelmsdorf (Haste), which is the lowest of the boundary beds between the upper Hauterivian Aegocrioceras beds and the staffi Zone. The first fragments ofSimbirskites occur in bed 46, but Simbirskites staffi itself was not found below bed 48 (K. Wiedenroth in Mutterlose, 1997b, p. 100). Bed 44 (which correlates with bed 19 at the S-Bahn of Hannover Airport) yielded Emericiceras ressense sp. nov., E. kemperi sp. nov., E. nolani, E. subtilicostatum sp. nov., E. wermbteri, E. hannoverense sp. nov. and Crioceratites subisocostatus sp. nov. These species, except for E. ressense, have also been found in the staffi Zone above bed 48 together with Crioceratites hastensis sp. nov., C. vermiformis sp. nov., Emericiceras woeckeneri, E. serpenti­ num sp. nov., E. strombecki and E. gotti sp. nov. The two last-named also occur in the discofalcatus Zone together with Acrioceras aff. monopujaae yvanii and Acrioceras sp. Emericiceras ex gr. emerici occurs in the boundary bed between the discofalcatus and rarocinctum zones. Bed 83 of the lower Barremian rarocinctum Zone at the Gott quarry yieldedParancy ­ loceras aegoceras, the last Emericiceras nolani, E. sornayiforme sp. nov., Fissicostaticeras clav­ iferum, F. rarocinctum, F. rarocinctoides sp. nov., Hoplocrioceras phillipsi, Acrioceras sarstedtense sp. nov., A. sarasini, A. meriani and A. longum sp. nov. The greater part of the fissicostatum Zone is represented by the black shales of the so-called ‘Hauptblätterton’, which yield no ammonites. Bed 6 in the top part of the fis­ sicostatum Zone in the subway of Aegidientor Square yielded Uhligia minuta, U. aegidii sp. nov., Uhligia sp., Hoplocrioceras laeviusculum, Acrioceras crassicostatum, A. nodulosum, Fissicostaticeras fissicostatum, F. ex gr. fissicostatumand F. aequicostatoides. The four last-named species also occur in the fissicostatum-elegans zonal boundary bed 7 of the same