Taphonomic grades as a classification for fossiliferous assemblages and implications for paleoecology

Different degrees of transport and reworking impart different physical characteristics to fossiliferous assemblages (= different taphonomic grades) and reflect different time scales of deposition and accumulation. Well-preserved fossil assemblages (= high taphonomic grade) generally reflect accumulation over short time spans; as taphonomic grade decreases, the time represented by the accumulation of the fossiliferous assemblage increases. The taphonomic grade of a fossil assemblage changes in one direction (high to low) with time, and provides a measure against which paleoecologists can evaluate other aspects of the fauna that may fluctuate through time. Beds of the same taphonomic grade reflect similar depositional histories. Characterizing faunas in terms of their taphonomic grade provides a means by which temporally and spatially disparate faunas may be compared.