Biological problems concerning fossilizable dinoflagellates

Abstract

Considerable progress has been made in the last few years toward a solution to an old micropaleontological problem, namely, that of the “biological affinities of hystrichospheres.” Today it can be said with some certainty that hystrichospheres (sensu stricto) as well as “typical” fossil dinoflagellates are homologous with the resting cysts or spores of living peridinealean dinoflagellates, but this does not completely resolve the original problem. Several important aspects of the biology of modern dinoflagellate cysts are very poorly understood or documented. These biological matters include the causes and mode of cyst formation and the genetic and physiological functions they perform. This contribution is devoted firstly to a review of recently acquired knowledge of modern dinoflagellate cysts that have micropaleontological interest and, secondly to a brief discussion of some of the biological problems that concern them.