The Asian land mammal ages, acronym ALMA, establish a geologic timescale for prehistoric Asian fauna, from the Paleocene to the Pleistocene. These periods are referred to as ages, stages, or intervals and were established using geographic place names where fossil materials where obtained. Many of the ALMAs are based on corresponding faunas found in the Erlian Basin in Inner Mongolia, China.
The basic unit of measure is the first/last boundary statement. This shows that the first appearance event of one taxon is known to predate the last appearance event of another. If two taxa are found in the same fossil quarry or at the same stratigraphic horizon, then their age-range zones overlap.
Ages Direct radiometric dating of all ALMAs has not proven possible. Few absolute dates have been proposed, and those that have been are approximate and based on correlations to faunas in other parts of the world.
+AgeLower boundaryUpper boundaryCorrelationCorrelation (NALMA)NihewanianPleistoceneYouheanLate PlioceneLate BlancanJingleanEarly PlioceneLate Hemphillian–early BlancanBaodeanLate MioceneLate Clarendonian–early HemphillianBahean~11.1 MaMiddle–late MioceneClarendonianTunggurian~11.1 MaEarly–middle MioceneBarstovianShanwangian~19.5 MaEarly MioceneLate HemingfordianXiejian~23.03 Ma~19.5 MaEarly MioceneTabenbulakian~31 Ma/30.6 Ma~23.03 MaLate Oligocenelate Whitneyan–early HemingfordianHsandagolian~33.9 Ma/33.3 Ma~31 Ma/30.6 MaEarly–middle Oligocene (early Rupelian)Orellan–middle WhitneyanKekeamuanEarly–middle OligoceneLate Orellan–early WhitneyanHouldjinianEarly OligoceneEarly OrellanErgilian~37.8 Ma~33.9 MaLate Eocene (Priabonian)ChadronianUlangochuian~39.9 Ma ~37.8 MaLate Eocene (late Bartonian)DuchesneanSharamurunian~42.7 Ma~39.9 MaMiddle–late Eocene (Late Lutetian–early Bartonian)Late Uintan (Ui3)Irdinmanhan~47.8 Ma~42.7 MaMiddle Eocene (Early–Middle Lutetian)Early–middle Uintan (Ui1–Ui2)Arshantan~52.1 Ma~47.8 MaEarly Eocene (late Ypresian)BridgerianBumbanian~56.0 Ma~52.1 MaEarly Eocene (early Ypresian)WasatchianGashatan~56.0 MaLate PaleoceneLate ClarkforkianNongshanianLate PaleoceneTiffanian–early ClarkforkianShanghuanEarly PaleocenePuercan–Torrejonian
Other continental ages
European land mammal age North American land mammal age South American land mammal age African land mammal age
See also Biochronology
References