Hoedemakers K (9 results)

pp. 241-352, numerous photos on 37 plates in text, 5 figs., tables, refs. 4to. Paperbound, plain new wrappers. Fine. - [gkt.ds.1005A].

The dentitions of the extant species Heterodontus mexicanus Taylor & Castro-Aguirre, 1972 and Heterodontus quoyi (Fr?menville, 1840) (Elasmobranchii, Chondrichthyes) is studied, clarifying all intraspecific and interspecific characteristics for these two species, thus forming a base in the understanding of francisci-type dentitions. Dignathic heterodonty was observed in H. mexicanus. 32 pp., 4 plates, 8 color & 8 b/w figs, br. 4.…

Early Eocene batomorph faunas, represented by isolated teeth from the London Clay Formation, LCF (Division D, lower Sheppey Member, lower NP12) at Burnham-on-Crouch, Essex, UK, and the Tielt Formation (Egemkapel Clay Member) and overlying Hyon Formation (Egem Sand Member, middle to upper NP12) at Egemkapel, western Flanders, Belgium, are described and illustrated. Whereas the Burnham fauna is from an outer neritic, deep-water environment, the faunal assemblages recovered from different stratigraphic levels in the Egemkapel Clay and Egem Sand Members are characteristic of mid to inner neritic settings. We also examined a small batomorph fauna from the upper levels of the Roubaix Clay Member of the Kortrijk Clay Formation exposed in the Koekelberg Clay Pit at Marke, Belgium. The upper Roubaix Clay Member is considered penecontemporaneus with Division D of the LCF, but was deposited in a mid-neritic environment. In all, we identified 13 batomorph taxa in the Sheppey Member, 12 in the Roubaix Clay Member, 23 in two different beds of the Egemkapel Clay Member, and 21 taxa in five beds of the Egem Sand Member. Three new species are described: Essexraja ypresiensis gen. et sp. nov., Casierabatis lambrechtsi gen. et sp. nov., and Eurasiabatis occlusostriata gen. et sp. nov. Based on detailed comparisons with the dentition and dental morphology of living stingrays, four species previously included in the genus ?Dasyatis? are re-allocated to new dasyatoid genera: Casierabatis jaekeli (Leriche, 1905) comb. nov., Sheppeytrygon davisi (Casier, 1966) comb. nov., Serratodasyatis tricuspidata (Casier, 1946) comb. nov., and Belgabatis thierryi (Smith, 1999) comb. nov. The rhinopristiform ?Rhinobatus? bruxelliensis Jaekel, 1894 is transferred to the new genus Glaucopristis. A stratigraphic range chart for batomorph taxa in the late Paleocene, Ypresian, and Lutetian of the North Sea Basin is presented. This chart may be considered as a starting point for additions and updates in future works, because identifications of some small-toothed rhinopristiform and dasyatoid species reported in the literature appear doubtful and the stratigraphic coverage of several species, especially those from outer neritic habitats, is insufficiently known. 172 pp., 77 figs, 1 tab., br. 4.…

190 S., 32 Abb., 1 Tab., 16 Taf., Behandelt werden die miozänen Seeigel, Krabben und Mollusken des berühmten Fundortes Gram/DK. Palaeontos 7. Sprache: Deutsch Gewicht in Gramm: 1500.

1) Rasmussen, E.S.: The geology of the upper Middle - Upper Miocene Gram Formation in the Danish area. 14 textpages, 10 textfigures Summary: Sediments of the upper Middle - Upper Miocene Gram Formation are distributed in central, west and south Jylland, Denmark. The Gram Formation is subdivided into three units: bottom to top the glaucony-rich, lowermost part, the Gram Clay, and the Gram sand. The sediments of the Gram Formation were deposited in an open marine depositional environment. The sediments of the Gram Formation were deposited in an open-marine environment. The glaucony-rich part was laid down under maximum transgression of the sea during the late Middle Miocene, when the north-eastern boundary of the North Sea was possibly located near the Sorgenfrei-Tornquist Zone in northern Jylland and Sk?ne. Water depths were up to 100 m in the area covered by the present-day west Jylland, but exceeded 500 m in the central part of the North Sea. In the Upper Miocene, outbuilding of clastic sedimentary wedges from the Fennoscandian Shield occurred from both the north and east. This resulted in a high sedimentation rate during the deposition of the Gram Clay. Locally, especially around salt structures, deeper, partly anoxic, restricted depositional environments prevailed. Expansion of these anoxic environments may have resulted in extreme environmental conditions and resulted in mass mortality shown by well-defined concretion horizons containing impressions of crabs. The uppermost part of the Gram Clay, with fine-grained storm-sand layers, and the Gram sand indicate periodical proximity of the shoreline. Possibly as a result of increased subsidence of the North Sea Basin in the Upper Miocene, up to 400 m of mainly shelfal deposits were laid down in most parts of the eastern North Sea Basin. 2) Beyer, C.: A magnetic analysis of the Late Miocene Gram Formation, Denmark. 10 textpages, 8 textfigures Summary: Based on the assumption that the geomagnetic secular variation in the Late Miocene possessed characteristics similar to the Quaternary secular variation, the accumulation rates of the Miocene Gram Formation was estimated by a magnetic analysis of a 16m vertical profile. The magnetic susceptibility, intensity and direction were measured and interpreted with respect to grain size, magnetic polarity and variation of the rate of accumulation. The analyses showed a general increase of accumulation rate upwards in the profile from approximately 0.03mm/y to 0.40mm/y. The sedimentation was extremely slow and possibly discontinuous in the lowermost part of the sequence, part of which is interpreted as a condensed section. The rest of the sampled profile showed more rapid and relatively continuous sedimentation during a time of normal polarity. A reverse polarity zone of 1.6m thickness was revealed in the interval 1.2-2.8m. The duration of this polarity zone is estimated to less than 70.000 years which leaves only three possibilities for correlation to the GPTS for the Tortonian stage, approximately 7.1 m.y., 7.4 m.y. or 9.9 m.y. The results indicate that the lowermost 3m were deposited during approximately 100.000 years and the 8m above this interval were deposited during approximately 20.000 years. The lowermost 8 m of the formation was not accessible in the clay pit but is known from nearby wells. This part of the sequence contains glauconite sand at the base and was thus deposited considerably slower than the studied sequence. 3) Piasecki, S.: Dinoflagellate cysts of the Middle ? Upper Miocene Gram Formation, Denmark. 17 textpages, 4 textfigures, 3 plates Summary: The dinoflagellate cysts of the Gram Formation provide the biostratigraphic framework for the determination of the age of the formation and reflect environmental and palaeoclimatic conditions during deposition. The age of the Gram Formation is Late Serravallian and Tortonian (late Middle Miocene to early Upper Miocene) estimated on the basis of dinoflagellate cyst biostratigra.…

190 pp., 32 text figures, 16 plates, 4to, paperbound. Very good copy, as new.A collection of six papers. By far the largest is K.I. Schnetler?s work on the Mollusca (128 p., 6 text figs, 11 plates). This is Palaeontos 7. The plates show well-preserved shells; SEM photos show protoconchs and microscopic species. Several species are new.…

190 p., 32 figs, 3 tables, 16 pls, 4to, paperbound. Palaeontos 7.

190 p., 32 figs, 3 tables, 16 pls, 4to, paperbound. Palaeontos 7.