The Fiskeler Member () of the Rødvig Formation is a notable geologic locality deposited during the Cretaceous–Paleogene boundary and the earliest part of the Danian (early Paleocene; ). It is known from exposures at Stevns Klint in Denmark.
History The fiskeler was discovered by Søren Abildgaard in 1759Abildgaard, S. (1759). Description of Stevns Klint and its natural oddities. and was named fiskeler by Johan Georg Forchhammer in 1826Forchhammer, J. G. (1826). On the Geognostic Conditions in a Part of Zealand and the Neighboring Islands. before being described by Richard Taylor and Richard Phillips in 1827.Taylor, R. & Phillips, R. (1827). The Philosophical magazine, or Annals of chemistry, mathematics, astronomy, natural history and general science. London : Richard Taylor (p. 99) Charles Lyell noted the absence of fossils in 1835,Lyell, C. (1835). On the Cretaceous and Tertiary Strata of the Danish Islands of Seeland and Moen. while Forchhammer was able to locate fossils at the site in 1849, using the name fiskeler for the first time in published literature.Forchhammer, J. G. (1849). The Newer Chalk in Denmark.
It was linked to the Cretaceous–Paleogene boundary during 1980 as a reference point for the stratigraphy and iridium content from the Chixculub impactor which struck Mexico.
Geology
The dark marl layer of fiskeler, mainly five to ten centimeters thick, clearly marks the Cretaceous–Paleogene boundary and overlies the Maastrichtian age Tor Formation as an unconformity. The is enriched in iridium, a fact used as an argument for the Alvarez hypothesis that the worldwide Cretaceous–Paleogene mass extinction was caused by the impact of an asteroid. It also suggested that when the fiskeler was deposited, a sudden change in the local sea level occurred.Adolfssen, J. S., & Ward, D. J. (2014). Crossing the boundary: An elasmobranch fauna from Stevns Klint, Denmark. Palaeontology, 57(3), 591–629. https://doi.org/10.1111/pala.12079
It underlies the Cerithium Limestone Member which is Danian in age and contains Paleocene ammonites.
Paleontology
The fiskeler contains fossils of animals directly killed by the Chixculub impactor, including an abundance of scales and teeth from fish (with most being microscopic in size), with few other fossils of which include mussels and zoophytes. The first chondrichthyan fossils (including thirty-one distinct species and one indeterminate specimen) from the fiskeler were described by Adolfssen & Ward (2014). This suggested the fauna was similar to Maastrichtian Germany and Danian Sweden,Herman, J. (1982b). Die Selachier-Zähne aus der Maastricht-Stufe von Hemmoor, Niederelbe (NW-Deutschland). Geologisches Jahrbuch A, 61, 129–159.Siverson, M. (1993a). Late Cretaceous and Danian neoselachians from southern Sweden. Lund Publications in Geology, 110, 1–28. linking the fiskeler to the Tethys Ocean.Cappetta, H. (1980). Les sélaciens du Crétacé supérieur du Liban. I: Requins. Palaeontographica, Abteilung A, 168, 69–148.
Only one three-dimensional fish specimen has been found within the fiskeler, and it was described by Forchammer (1849). It is missing the tail and head, and it probably belonged to Berycidae.
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