CHEMOSTRATIGRAPHIC RECONSTRUCTION OF BIOFACIES - MOLECULAR EVIDENCE LINKING CYST-FORMING DINOFLAGELLATES WITH PRE-TRIASSIC ANCESTORS

New data from numerous detailed mass-spectrometric studies have detect ed triaromatic dinosteroids in Precambrian to Cenozoic rock samples, T riaromatic dinosteroids are organic geochemicals derived from dinoster ols, compounds known in modern organisms to be the nearly exclusive wi dely occurring products of dinoflagellates. We observed the ubiquitous occurrence of these dinosteroids in 49 Late Triassic through Cretaceo us marine source rocks and the absence of them in 13 Permian-Carbonife rous source rocks synergistic with the dinoflagellate cyst record, How ever, finding dinosteroids in lower Paleozoic and Precambrian strata p resents challenging results for molecular paleontologists, evolutionar y biologists, palynologists, and especially for those concerned with t he food web at various times of biological crisis, Other than the few species known as parasites and symbionts, many other dinoflagellate sp ecies are important as primary producers, The presence of Precambrian to Devonian triaromatic dinosteroids gives chemostratigraphic evidence of dinoflagellates (or other organisms with similar chemosynthetic ca pabilities) in rocks significantly older than the oldest undisputed di noflagellate fossils (dinoflagellate cysts from the Middle Triassic, s imilar to 240 Ma), and older than the putative Silurian (similar to 42 0 Ma) dinocyst, Arpylorus antiquus (Calandra) Sargent, from Tunisia, T his systematic chemostratigraphic approach can shed light not only on lineages of dinoflagellates and their precursors, but potentially on m any other lineages, especially bacteria, algae, plants, and possibly s ome metazoans.