MP 20

from Wikipedia, the free encyclopedia

The European land mammal horizon MP 20 is the uppermost of the five land mammal horizons of the headonium . It is located immediately before the Grande Coupure at the turn of the Eocene / Oligocene .

Name and history

The name MP 20 is an abbreviation that is derived from the English. Mammal paleogens , i.e. mammalian paleogens . The paleogene contains 30 MP horizons .

The subdivision of the European paleogene into 30 MP horizons was proposed in 1976 by Volker Fahlbusch at the International Symposium on Mammalian Stratigraphy .

stratigraphy

The land mammal horizon MP 20 follows MP 19 , followed by MP 21 . MP 20 is the uppermost of the five land mammal horizons of the headonium (MP 17A, MP 17B, MP 18, MP 19 and MP 20) and contains the frohnstettense suevicum biozone.

Temporal equivalents of the MP 20 on other continents are the beginning of the orellum in North America and the beginning of the Shandgolium in Asia .

Fossils

Entelodon lived during the land mammal horizon
MP 20 (reconstruction by Heinrich Harder )

The beginning of MP 20 is marked by the last appearance (Last Appearance Date or LAD) of the camel-like Xiphodontidae . Towards the end of MP 20, the camel-like Amphimerycidae die out. The early pig-like Entelodon lived during the MP 20 .

Geological case study

The Hamstead member of the Bouldnor formation in the Hampshire basin of southern England is to serve as an example for the land mammal horizon MP 20 . It illustrates in a very impressive way the biodiversity and the upheaval in the fauna community of that time :

  • Lower Hamstead Member:

Amphidozotherium cayluxi , Amphiperatherium exile , Anoplotherium latipes , Bransatoglis planus , Butselia biveri , Cryptopithecus , Eotalpa anglica , Glamys fordi , Palaeotherium curtum , Palaeotherium muehlbergi , Paradoxonycteris tobieni , Pseudoltinomys cuvieri , Ronzotherium sp. , Stehlinia minor , Suevosciurus ehingensis , Suevosciurus fraasi , Theridomys bonduelli and Xiphodon gracilis .

  • Upper Hamstead Member:

Amphicynodon sp. , Amphiperatherium exile , Amphiperaterium minutum , Asteneofiber , Atavocricetodon atavus , Bothriodon velaunus , Butseloglis micio , Cryptopithecus , Elomeryx porcinus , entelodon magnus , Eomys , Glamys fordi , Hyaenodon dubius , Isoptychus margaritae , Leptadapis sp. , Myxomygale antiqua , Paradoxonycteris tobieni , Pecora , Peratherium perriense , Pseudoltinomys gaillardi , Ronzotherium romani , Stehlinia gracilis , Tapirulus hyracinus and Tetracus .

It should be noted here that the Lower Hamstead member still has Xiphodon (and therefore should be included in MP 19), but MP 20, by definition, begins with the extinction of the Xiphodontidae. The fauna of the Upper Hamstead member therefore clearly represents MP 20, also recognizable by the occurrence of Entelodon .

In addition to Entelodon, the following taxa were definitely present in the MP 20:

Age

The absolute age of the land mammal horizon MP 20 ranges between 34.0 and 33.8 million years BP . MP 20 thus marks the Upper Priabonian and just barely protrudes into the Lower Oligocene ( Rupelian ). The upper limit coincides with the negative oxygen excursion Oi-1, the beginning of the glaciation in Antarctica .

MP 20 took only around 200,000 years to complete and is of the shortest duration among all MP horizons.

literature

swell

  • Gradstein, Ogg, J. & Smith, A .: A Geologic Time Scale 2004 . Ed .: Cambridge University Press. 2004, ISBN 0-521-78673-8 .

Individual evidence

  1. ^ Fahlbusch, V .: Report on the International Symposium on Mammalian Stratigraphy of the European Tertiary . In: Newsletters on Stratigraphy . tape 5 . Munich April 11, 1976, p. 160-167 .