The Rødvig Formation is a geological formation deposited during the earliest part of the

Danian The Danian is the oldest age or lowest stage of the Paleocene Epoch or Series, of the Paleogene Period or System, and of the Cenozoic Era or Erathem. The beginning of the Danian (and the end of the preceding Maastrichtian) is at the Creta ...

(early

Paleocene The Paleocene, ( ) or Palaeocene, is a geological epoch that lasted from about 66 to 56 million years ago (mya). It is the first epoch of the Paleogene Period in the modern Cenozoic Era. The name is a combination of the Ancient Greek ''pal ...

; ) and it was first identified by Richard Taylor and Richard Phillips in 1827. It is known from exposures at

Stevns Klint Stevns Klint, known as the Cliffs of Stevns in English, is a white chalk cliff located some southeast of Store Heddinge on the Danish island of Zealand. Stretching along the coast, it is of geological importance as one of the best exposed C ...

in Denmark. The unit lies directly above the K–Pg boundary and contains fossils that provide a record of the recovery of various groups following the Cretaceous–Paleogene extinction. The upper boundary of the formation is an unconformity in the form of a

hardground Carbonate hardgrounds are surfaces of synsedimentarily cemented carbonate layers that have been exposed on the seafloor (Wilson and Palmer, 1992). A hardground is essentially, then, a lithified seafloor. Ancient hardgrounds are found in limestone ...

, beneath which the formation is sometimes missing. The base of the unit is irregular due to the presence of mounding associated with

bryozoa Bryozoa (also known as the Polyzoa, Ectoprocta or commonly as moss animals) are a phylum of simple, aquatic invertebrate animals, nearly all living in sedentary colonies. Typically about long, they have a special feeding structure called a ...

, causing variations in thickness. The unit is subdivided into the lower ''Fiskeler Member'' mainly formed of marl and the overlying ''Cerithium Limestone Member''.

Geology

The dark layer of , mainly five to ten centimeters thick, clearly marks the

Cretaceous–Paleogene boundary The Cretaceous–Paleogene (K–Pg) boundary, formerly known as the Cretaceous–Tertiary (K–T) boundary, is a geological signature, usually a thin band of rock containing much more iridium than other bands. The K–Pg boundary marks the end ...

and overlies the

Maastrichtian The Maastrichtian () is, in the ICS geologic timescale, the latest age (uppermost stage) of the Late Cretaceous Epoch or Upper Cretaceous Series, the Cretaceous Period or System, and of the Mesozoic Era or Erathem. It spanned the interv ...

age

Tor Formation The Tor Formation is a geological formation of late Campanian to Maastrichtian (uppermost Cretaceous) age. It forms the part of the Chalk Group in the North Sea. It is an important reservoir for oil and gas in fields such as Valhall. It overlies ...

. The is enriched in

iridium Iridium is a chemical element with the symbol Ir and atomic number 77. A very hard, brittle, silvery-white transition metal of the platinum group, it is considered the second-densest naturally occurring metal (after osmium) with a density of ...

, a fact used as an argument for the

Alvarez hypothesis The Alvarez hypothesis posits that the mass extinction of the non-avian dinosaurs and many other living things during the Cretaceous–Paleogene extinction event was caused by the impact of a large asteroid on the Earth. Prior to 2013, it was com ...

that the worldwide Cretaceous–Paleogene mass extinction was caused by the impact of an asteroid. Following the boundary is a layer of darker clay and chalk between 10 and 30 cm thick, corresponding to a period of low biological diversity on the sea floor immediately after the K-Pg Boundary.

Paleontology

The Rødvig Formation contains a remarkably detailed and complete fossil record of the biota in Northern Europe during the early Paleogene. The layers are rich in microfossils, containing many species of millimeter-long suspension feeders. A wide variety of

benthic The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from ancient Greek, βένθος (bénthos), meaning "t ...

foraminifera Foraminifera (; Latin for "hole bearers"; informally called "forams") are single-celled organisms, members of a phylum or class of amoeboid protists characterized by streaming granular ectoplasm for catching food and other uses; and commonly ...

species have been identified from the Rødvig Formation, with significant differences in abundance across the K–Pg boundary demonstrating the biotic turnover that occurred during the mass extinction event.

Ammonites

The Rødvig Formation was the first known site to document the short-term survival of ammonites into the

Paleogene The Paleogene ( ; also spelled Palaeogene or Palæogene; informally Lower Tertiary or Early Tertiary) is a geologic period and system that spans 43 million years from the end of the Cretaceous Period million years ago (Mya) to the beginning of ...

, when they were originally thought to have gone extinct at the K-Pg boundary. Ammonites are thus only known from the first 200,000 years of the Cerithium Limestone, before disappearing from the formation around 64.8 million years ago. Two ammonite species are known from the Rødvig Formation: '' Baculites vertebralis'', notable for having a nearly straight shell, and '' Hoploscaphites constrictus'', which may have been a subspecies of ''

Scaphites ''Scaphites'' is a genus of heteromorph ammonites belonging to the Scaphitidae family. They were a widespread genus that thrived during the Late Cretaceous period. Morphology ''Scaphites'' generally have a chambered, boat-shaped shell. The init ...

'',''Hoploscaphites''
at

Fossilworks Fossilworks is a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database, a large relational database assembled by hundreds of paleontologists from around the world. History Fossilworks was cre ...

.org and is also the most common ammonite known from the

Known fossil fauna

The known fossil fauna found in the Rødvig Formation includes: Heinberg 1999
/ref> * ''

Acar Acar is a type of vegetable pickle of Maritime Southeast Asia, most prevalent in Indonesia, Malaysia, Singapore and Brunei. It is a localised version of Indian '' achar''. It is known as atjar in Dutch cuisine, derived from Indonesian ''acar ...

'' sp. *

Arcida The Arcida is an extant order of bivalve molluscs. This order dates back to the lower Ordovician period. They are distinguished from related groups, such as the mussels, by having a straight hinge to the shells, and the adductor muscles being ...

indet. * '' Arcopsis christinae'' * '' Arcopsis'' sp. * '' Baculites vertebralis'' * '' Barbatia'' sp. * ''

Bathyarca ''Bathyarca'' is a genus of bivalves belonging to the family Arcidae. The genus has cosmopolitan distribution. Species Species: *'' Bathyarca adelaideana'' *'' Bathyarca anaclima'' *'' Bathyarca bellatula'' *''Bathyarca pectunculoides ' ...

'' sp. *

Bivalvia Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, biv ...

indet. * ''

Brachidontes ''Brachidontes'' is a genus of mussels in the family Mytilidae.Abbott, R.T. & Morris, P.A. ''A Field Guide to Shells: Atlantic and Gulf Coasts and the West Indies.'' New York: Houghton Mifflin, 1995. 17. Species The following are the species cu ...

'' sp. * ''Carcharias'' aff. ''gracilis'' * '' Centroscymnus praecursor'' * '' Chlamydoselachus'' sp. * '' Cuspidaria ( Halonympha) kanae'' * ''

Corbulamella ''Corbulamella'' is an extinct genus of bivalves in the family Corbulidae. References External links * * Corbulidae Prehistoric bivalve genera {{bivalve-stub ...

'' sp. * '' Crassatella'' sp. * '' Crassescyliorhinus germanicus'' * ''

Cretalamna ''Cretalamna'' is a genus of extinct otodontid shark that lived from the latest Early Cretaceous to Eocene epoch (about 103 to 46 million years ago). It is considered by many to be the ancestor of the largest sharks to have ever lived, '' Otodu ...

'' sp. * '' Cuspidaria'' sp. * '' Cyclaster danicus'' * '' Cyrtodaria'' sp. * ''

Dacrydium ''Dacrydium'' is a genus of conifers belonging to the podocarp family Podocarpaceae. Sixteen species of evergreen dioecious trees and shrubs are presently recognized. The genus was first described by Solander in 1786, and formerly included many ...

'' sp. * '' Echinorhinus'' sp. * '' Eriphylopsis'' sp. * '' Euciroa'' sp. * '' Hemiscyllium hermani'' * '' Heterodontus rugosus'' * '' Hoploscaphites constrictus'' * '' Gregariella'' sp. * '' Leptosolen'' sp. * '' Limopsis ravni'' * '' Limopsis'' sp. * '' Loripes'' sp. * Lucinidae indet. * '' Martesia'' sp. * '' Miocardiopsis'' sp. * '' Myrtea'' sp. * ''

Nebrius ''Nebrius'' is a genus of carpet sharks in the family Ginglymostomatidae. It contains a single extant species, the tawny nurse shark (''Nebrius ferrugineus''), as well as a number of extinct species dating back to the Early Paleocene.Bourdon, ...

'' sp. * '' Nielonella'' sp. * '' Palaeocypraea spirata'' * ''Palaeogaleus'' cf. ''faujasi'' * ''Palaeohypotodus'' aff. ''bronni'' * '' Parasquatina cappettai'' * '' Paratriakis curtirostris'' * '' Portlandia arctica'' * '' Protocardia'' sp. * '' Pycnodonte vesicularis'' (='' Phygraea vesiculare'') * '' “Scyliorhinus” biddlei'' * '' “Scyliorhinus” elongatus'' * ''Spondylus fimbriatus'' * '' Squalus gabrielsoni'' * '' Syncylonema nilsoni'' * '' Synechodus faxensis'' (='' Paleospinax'') * ''

Thalassinoides ''Thalassinoides'' is an ichnogenus of trace fossil used to refer to "dichotomously or T-branched boxworks, mazes and shafts, unlined and unornamented". Facies of ''Thalassinoides'' increased suddenly in abundance at the beginning of the Mesoz ...

'' sp. * '' Thyasira'' sp. * '' Tylocidaris oedumi'' * '' Uddenia'' sp. * '' Unicordium'' sp, * '' Vetericardiella'' sp. * '' Yoldiella'' sp.

References

{{reflist, group=lower-alpha Danian Danian Stage Geology of Denmark