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Epicymatoceras vaelsense

 Faktiske data om fund 
Katalognummer:
886
Accessionsnummer:
DK 919
Samling:
Danekræsamlingen
Samler:
Statens Naturhistorisk Museum
Finder:
Mogens S. Nielsen
Bestemt af:
Marcin Machalski
Lokalitet:
Dania Kridtgrav, Mariager
Stratigrafi:
Højerup Member
Periode:
Sen Maastrichtien
Type:
Aftryk
Sediment:
Skrivekridt

Billede

Foto ©: Sten Lennart Jakobsen


 Beskrivelse:   af  Marcin Machalski 
The specimen, kindly made available for study by Mr Sten Lennart Jakobsen, a curator in Geologisk Museum, is rather poorly preserved, internal mould in chalk preservation, c.70 mm in maximum preserved diameter. According to the information of the collector, it comes from the uppermost Maastrichtian White Chalk as exposed at “’Dania quarry’ at Jutland.

At the genus level, the evaluated specimen can be identified as a nautilid Epicymatoceras as defined by Kummel (1956, 1964). This is a peculiar, atypical Cretaceous nautilid that is characterised by a strongly compressed, evolute (ammonite-like) conch with a subquadrate whorl section and flattened or slightly concave venter (Kummel, 1956; Jagt et al., 1998; Goolaerts and Frank, 2014).

In terms of its specific assignation, the specimen can be safely identified to be an immature or incomplete specimen of Epicymatoceras vaelsense (Binkhorst van den Binkhorst, 1862), the type species of the genus Epicymatoceras Kummel, 1956. To note are remnants of the delicate reticulate ornament of the innermost whorl, typical for nautilid embryonic conchs. The preservation of this ornament is rare in fossil nautilid moulds (e.g. Malchyk et al., 2016).

To date, Epicymatoceras vaelsense was recorded from the southeast Netherlands, northeast Belgium (Binkhorst van den Binkhorst, 1862; Jagt 1998; Jagt 2012; Goolaerts and Frank 2014) and northwest Germany (Schlüter 1876; Holzapfel 1877). The type material of E. vaelsense is from the lower Maastichtian in the Vaals area, province of Limburg, the Netherlands (Binkhorst van den Binkhorst, 1862) (see Jagt et al. 1998 and Jagt 2012 for more detailed data on the stratigraphical and geographical distribution of E. vaelsense in the Netherlands, Belgium and Germany). Schlüter (1876) described two specimens from the ‘Mucronaten-Kreide’ (lower Maastrichtian in current terms), one from Vaels (Vaals) near Aachen and the other from Lüneburg, northern Germany. Schönfeld (1985) recorded Epicymatoceras vaelsense from upper Santonian strata in Westphalia (northwest Germany), but this record must be regarded as doubtful. The species was recently described from the uppermost Campanian-lower Maastrichtian of Poland (Malchyk et al., 2016 and submitted). These authors stressed the importance of E. vaelsense for further evaluation of the systematics and phylogeny of the Cretaceous representatives of the cymatoceratid nautilid clade.

There are several undescribed specimens of Epicymatoceras vaelsense from the lower/upper Maastrichtian interval of the Danish White Chalk in the collections of the Geological Museum, Copenhagen (identification based on photographs kindly sent to the author of the present report by Sten Lennart Jakobsen).

The evaluated specimen of E. vaelsense, originating from the topmost Maastrichtian chalk as exposed at the quarry ‘Dania’, Jylland (Jutland), northern Denmark is the stratigraphically youngest record of this important nautilid over the world. It extends the range of the rare and palaeobiologically important nautilid species and genus into the latest Maastrichtian, what is of extreme importance in the light of the current discussion on the different fates of the ammonoids and nautilids across the Cretaceous-Paleogene mass extinction (see Landman et al. 2014, 2015).

Therefore, the scientific interest of this specimen is beyond doubt, and its declaration as a Danekrae specimen and subsequent deposition in a public museum will make it available for a much needed further scientific study that I am ready to perform in due time.


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