Taphonomic Bias in Pollen and Spore Record: A Review

Lanny H. Fisk

The high dispersibility and ease of pollen and spore transport have led researchers to conclude erroneously that fossil pollen and spore floras are relatively complete and record unbiased representations of the regional vegetation extant at the time of sediment deposition. That such conclusions are unjustified is obvious when we remember that palynomorphs are merely organic sedimentary particles and undergo hydraulic sorting not unlike clastic sedimentary particles. Prior to deposition in the fossil record, pollen and spores can be hydraulically sorted by size, shape, and weight, subtly biasing relative frequencies in fossil assemblages.

Sorting during transport results in palynofloras whose composition is environmentally dependent. Therefore, depositional environment is an important consideration to make correct inferences on the source vegetation.

Sediment particle size of original rock samples may contain important information on the probability of a taphonomically biased pollen and spore assemblage. In addition, a reasonable test of hydraulic sorting is the distribution of pollen grain sizes and shapes in each assemblage. Any assemblage containing a wide spectrum of grain sizes and shapes has obviously not undergone significant sorting. If unrecognized, taphonomic bias can lead to paleoecologic, paleoclimatic, and even biostratigraphic misinterpretations.

AAPG Search and Discovery Article #91043©1986 AAPG Annual Convention, Atlanta, Georgia, June 15-18, 1986.