IS ABERRANCY A RELIABLE INDICATOR FOR MAJOR PALEOCLIMATIC DISTURBANCE?

Abstract: Aberrant forms of many different spore and pollen taxa (sporomorphs) are often used to assess timings and extent of environmental stress at major extinction/climate events. However, little is known about the normal level of malformations in these taxa. Malformation can manifest in several different ways, including significant size differences (± from the accepted range for the species), retention of pollen/spores within tetrads, and unusual and inconsistent morphological aberrations. This study analyses one commonly used pollen genus, Classopollis, and its aberrant forms, from the Bajocian of Argentina. Tetrads, including those incorporating malformed/aborted pollen grains, are found to be common, showing that tetrads of Classopollis are not a reliable signal of major environmental disturbance. The results and discussion presented here emphasize why palynological data must be interpreted in context of the depositional dynamics, facies changes and how they affect the assemblages in conjunction with understanding variations in the strategies of individual flora.