PROLIFERATION OF OBERHAUSERELLIDAE DURING THE RECOVERY FOLLOWING THE LATE TRIASSIC EXTINCTION: PALEOECOLOGICAL IMPLICATIONS

A paleoecological study of benthic foraminifera through the lower Hettangian in the Doniford Bay section (west Somerset, U.K.) is presented. The sudden and brief appearance of Oberhauserellidae in the aftermath of the Late Triassic extinction is defined as a proxy for environmental perturbations indicating severe biotic stress conditions. Oberhauserellidae, associated with the genus Reinholdella are distinguished from other species by a high abundance, low diversity, high dominance and an abnormally small size. This suite of characters mimics an opportunistic behavior where these r-strategists and grazer feeders maximize their full ecological potential at a time of low-oxygen conditions on the sea-floor and a high food supply: both of which appear to be the main triggers of this paleoecological change. The disappearance of these opportunistic benthic foraminifera coincides with the appearance of infaunal, low-oxygen-tolerant generalists, and the restoration of stable environmental conditions (e.g., well-stratified water mass and oligotrophic conditions), characterizing the initial stages of recovery following the Late Triassic extinction event.