The last ammonite?

Bulletin of the Geological Society of Denmark

Andersen, S. B.¹  Jakobsen, S. L.:¹  Jagt, J. W. M.¹ 

[1] The echinoid Gauthieria alterna from the uppermost Maastrichtian of Denmark. Bulletin of the Geological Society of Denmark, Vol. 45, pp. 23–26. Copenhagen, 1998–09–25.
The present record from the white chalk of Holtug (Stevns Klint, Sjælland) of the small, distinctive phymosomatid echinoid Gauthieria alterna (Kutscher, 1985) constitutes a notable addition to the latest Maastrichtian echinoid faunas in Denmark.
Although both specimens available are crushed, preservation on the whole is better than the type material from the upper Lower Maastrichtian of Rügen (northeast Germany), and enables a more detailed description of the species, which was originally placed in Hemithylus Arnaud, 1896 but which is here transferred to the genusGauthieria Lambert, 1888. One of the specimens preserves a single demipyramid and epiphysis of the lantern.

关键词: Echinoidea;    Phymosomatidae;    Maastrichtian;    Natuurhistorisch Museum Maastricht;    P.O. Box 882;    NL-6200 AW Maastricht;    the Netherlands;    geolsba [at] aau [dot] dk ]"'>Søren Bo Andersen [ geolsba [at] aau [dot] dk ];    Geological Institute;    C.F. Møllers Allé 120;    DK-8000 Aarhus C;    Denmark;    SLJ [at] savik [dot] geomus [dot] ku [dot] dk ]"'>Sten Lennart Jakobsen [ SLJ [at] savik [dot] geomus [dot] ku [dot] dk ];    GeologicalMuseum;    Øster Voldgade 5-7;    DK-1350 Copenhagen K;    Denmark. 20 July 1998.;   

学科分类：地球科学(综合)

来源: Dansk Geologisk Forening

【 摘 要 】

A fragment of red-brown flint with imprints of two ammonite aptychi has been found loose on the beach of the Boesdal quarry on Stevns Klint. The quarry exposes only Lower Danian bryozoan limestone. The nearest occurrence of Maastrichtian strata is 400 m to the west in Skeldervig bay, north of Korsnæb, where 50 cm of chalk with small dark-grey and black flint nodules are exposed below the basal Danian Fish Clay over a stretch of 15 m. Maastrichtian chalk is normally dark-grey to black and has a thin white rind. Danian flint is much more variable in colour and degree of silicification, and red-brown varieties are common. The two aptychi clearly belong to the same ammonite individual and cannot have been redeposited from the crests of the top-Maastrichtian mounded bryozoan chalk. Finds of the ammonite Hoploscaphites constrictus and Baculites sp. have been reported in the literature from the lowermost Danian Cerithium Limestone. They are normally considered reworked, but their age should possibly be re-evaluated in the light of the new find. It is thus very likely that two ammonite genera survived the mass extinction at the K-T boundary and lived on as rare elements in the earliest Tertiary fauna.

【 授权许可】

Unknown