DECOUPLED TERRESTRIAL AND MARINE ECOLOGICAL RECOVERY AFTER THE END-TRIASSIC MASS EXTINCTION

Constructing trends in functional diversity through mass extinction intervals is critical for understanding how ecosystems have responded to major environmental perturbations throughout Earth history. Ecospace analyses, which classify organisms in a multivariate space according to their ecological traits, have proven particularly useful for reconstructing changes in ecological structure and functional recovery through Phanerozoic mass extinctions. Specifically, marine ecospace analyses that categorize animals according to tiering, feeding behavior, and motility traits have previously been used to understand how marine ecosystems have changed through mass extinction intervals. However, no analogous ecospace methodology exists for the terrestrial fossil record, limiting comparable studies of terrestrial and marine functional ecology, as well as our general understanding of how terrestrial and marine ecosystems respond differently to climate change.

We developed a novel terrestrial ecospace method which, like the traditional marine ecospace, classifies animals in terms of their tiering, feeding, and motility traits. We applied the marine and terrestrial ecospace analyses to fossil occurrences in the Paleobiology Database (PBDB) across the end-Triassic mass extinction (ETME). Each genus that occurs in the PBDB between the Norian (Triassic) to the Toarcian (Jurassic) was assigned an ecospace functional group according to its tiering, feeding, and motility traits. We conducted stage-level analyses of diversity, extinction intensity, and ecological structure to address how terrestrial and marine ecosystems compare in recovery during the Early Jurassic in the wake of the ETME. In stark contrast with marine ecosystems, we find that terrestrial ecosystems exhibit an observable decrease in functional diversity around the ETME, with the majority of functional groups experiencing high taxonomic turnover within functional groups and high ecological dissimilarity persisting through the Jurassic. We conclude that terrestrial ecosystems are particularly ecologically sensitive to the environmental perturbations associated with the ETME, causing early significant functional ecology instability which inhibited early recovery in Jurassic terrestrial ecosystems.