Upcoming Events
13 Nov (GEOL) James Kerr, Paleobiology
Nov 13, 2025, 4:30 - 5:30 PM
Speaker: James Kerr, George Washington University
Title: Biotic Interaction and Extinction: Encrusting and Boring Organisms During the Late Devonian Mass Extinction
Time: Thu, 13 Nov, 4:30pm
Location: Exploratory 1309 and via Zoom (for link, email lhinnov@gmu.edu)
Host: Linda Hinnov
ABSTRACT: Epibiotic and endobiotic organisms are common and diverse in the modern world as well as the fossil record, but their long-term responses to ecological perturbation are not well known. Mass extinctions involve large-scale environmental changes that directly impact many species but secondary effects can be experienced by the remaining organisms. This work seeks to address the questions: 1) What happens to epibiotic and endobiotic organisms during a mass extinction event? and 2) to what degrees are epibiotic and endobiotic commensals differentially affected by changing factors in their abiotic environments and by turnover among their hosts? In order to address these questions, skeletobionts (encrusters and borers of skeletal material) found on brachiopods were sampled from rocks of the Appalachian Basin that stratigraphically straddle a pulse of the Late Devonian Mass Extinction. Abundance, stratigraphic distribution, and settling behavior of the skeletobionts was documented. Multivariable Logistic Regression was then used to compare possible predictors of skeletobiosis including 1) stratigraphic position relative to extinction interval, 2) sculpture of brachiopod hosts, 3) body size of hosts, 4) onshore-offshore location, 5) substrate stability, and 6) extinction fate of hosts. No skeletobiont group was totally lost in the Appalachian basin through this event, but many experienced a drop in abundance. Across the extinction event, the distribution of skeletobionts shifted from being more host-controlled (body size, surface sculpture) to being more strongly controlled by onshore-offshore environmental gradient. Turnover of hosts had no significant effect on skeletobionts through the extinction event.
