Danian


Danian
System Series Stage Age (Ma)
Neogene Miocene Aquitanian younger
Paleogene Oligocene Chattian 23.03–28.4
Rupelian 28.4–33.9
Eocene Priabonian 33.9–37.2
Bartonian 37.2–40.4
Lutetian 40.4–48.6
Ypresian 48.6–55.8
Paleocene Thanetian 55.8–58.7
Selandian 58.7–61.7
Danian 61.7–65.5
Cretaceous Upper Maastrichtian older
Subdivision of the Paleogene Period according to the IUGS, as of July 2009.

The Danian is the oldest age or lowermost stage of the Paleocene epoch or series, the Paleogene period or system and the Cenozoic era or erathem. The beginning of the Danian age (and the end of the precessing Maastrichtian age) is at the Cretaceous-Tertiary extinction event 65.5±0.3 Ma. The age ended 61.7±0.2 Ma, being followed by the Selandian age.[1]

Contents

Stratigraphic definitions

The Danian was introduced in scientific literature by German-Swiss geologist Pierre Jean Édouard Desor in 1847. It is named after the Latin name for Denmark. The Montian stage from Belgian stratigraphy (named after the city of Mons) is now considered a junior synonym and is no longer in use.

The base of the Danian is defined at the iridium anomaly which characterized the Cretaceous-Paleogene boundary in stratigraphic sections worldwide. A section in El Kef, Tunisia was appointed as a reference profile (GSSP) for this important boundary.[2] The Danian is the oldest age of the Paleocene, defined at its base by the K-Pg boundary. It is very important because the readily recognized iridium anomaly and primitive Danian planktonic foraminifers define the base of the Danian. Danian foraminiferans repopulated the Paleocene seas after the Cretaceous mass extinction (Olsson et al., 1996). The first replacement foraminiferan of the Paleogene is the Globigerina eugubina, which is used to define the base of the Danian Age (Stainforth et al., 1975). This foraminiferan replaced the Cretaceous genus Globotruncana.

The top of the Danian stage (the base of the Selandian) is close to the boundary between biozones NP4 and NP5 from marine biostratigraphy. It is slighltly after the first appearances of many new species of the calcareous nannoplankton genus Fasciculithus (F. ulii, F. billii, F. janii, F. involutus, F. tympaniformis and F. pileatus) and close to the first appearance of calcareous nannoplankton species Neochiastozygus perfectus.

The Danian stage overlaps the Puercan and Torrejonian North American Land Mammal Ages and the Shanghuan and lowest part of the Nongshanian Asian Land Mammal Ages. It includes the oldest Mammal Paleogene zones, all included in the 1 - 5 group. [3]

Palaeontology

Though the dinosaurs were gone, the mammals, and other land animals remained small, none bigger than a large domestic cat. But most of the mammals' orders already had appeared. Numerous lineages of modern birds also survived, particularly in the area around Australia but also elsewhere, e.g. Scaniornis of the North Sea region. The oceans remained much the same as the Late Cretaceous seas, only that there was less life, no marine reptiles, and other lesser known animals.

References

Notes

  1. ^ See Gradstein et al. (2004) for the official geologic timescale
  2. ^ The GSSP for the Danian stage was established by Molina et al. (2006)
  3. ^ Alroy, John. "Mammal Paleogene zones". p. The Paleobiology Database. http://paleodb.org/cgi-bin/bridge.pl?action=processViewScale&scale_no=125. Retrieved 15 July 2009. 

Literature

  • Desor, P.J.É.; 1847: Sur le terrain Danien, nouvel étage de la craie, Bulletin de la Societé Géologique de France, série 2, 3, p. 179-181, ISSN 0037-9409.(French)
  • Gradstein, F.M.; Ogg, J.G. & Smith, A.G.; 2004: A Geologic Time Scale 2004, Cambridge University Press.
  • Molina, E.; Alegret, L.; Arenillas, I.; Arz, J.A.; Gallala, N.; Hardenbol, J.; Salis, K. von; Steurbaut, E.; Vandenberghe, N. & Zaghbib-Turki, D.; 2006: The Global Boundary Stratotype Section and Point for the base of the Danian Stage (Paleocene, Paleogene, "Tertiary", Cenozoic) at El Kef, Tunisia: original definition and revision, Episodes 29(4), p. 263-273, ISSN 0705-3797.
  • Olsson, R.K., Liu, C., and Van Fossen, M.; 1996:The Cretaceous-Tertiary catastrophe event at Millers Ferry, Alabama in Ryder, G., Fastovsky, D., and Gartner, S., eds., The Cretaceous-Tertiary Event and other catastrophes in Earth history: Geological Society of America Special Paper 307, p. 263-277.
  • Stainforth, R.M., Lamb, J.L., Lutherbacher H., Beard, J.H., and Jeffords, R.M.; 1975: Cenozoic planktonic foraminifera zonation and characteristics of index forms: The University of Kansas Paleontological Institute, Article 62, 425 p.


External links