The Impact of Global Warming and Anoxia on Marine Benthic Community Dynamics: an Example from the Toarcian (Early Jurassic)

The Pliensbachian-Toarcian (Early Jurassic) fossil record is an archive of natural data of benthic community response to global warming and marine long-term hypoxia and anoxia. In the early Toarcian mean temperatures increased by the same order of magnitude as that predicted for the near future; laminated, organic-rich, black shales were deposited in many shallow water epicontinental basins; and a biotic crisis occurred in the marine realm, with the extinction of approximately 5% of families and 26% of genera. High-resolution quantitative abundance data of benthic invertebrates were collected from the Cleveland Basin (North Yorkshire, UK), and analysed with multivariate statistical methods to detect how the fauna responded to environmental changes during the early Toarcian. Twelve biofacies were identified. Their changes through time closely resemble the pattern of faunal degradation and recovery observed in modern habitats affected by anoxia. All four successional stages of community structure recorded in modern studies are recognised in the fossil data (i.e. Stage III: climax; II: transitional; I: pioneer; 0: highly disturbed). Two main faunal turnover events occurred: (i) at the onset of anoxia, with the extinction of most benthic species and the survival of a few adapted to thrive in low-oxygen conditions (Stages I to 0) and (ii) in the recovery, when newly evolved species colonized the re-oxygenated soft sediments and the path of recovery did not retrace of pattern of ecological degradation (Stages I to II). The ordination of samples coupled with sedimentological and palaeotemperature proxy data indicate that the onset of anoxia and the extinction horizon coincide with both a rise in temperature and sea level. Our study of how faunal associations co-vary with long and short term sea level and temperature changes has implications for predicting the long-term effects of “dead zones” in modern oceans

Data from: Biotic invasion, niche stability, and the assembly of regional biotas in deep time: comparison between faunal provinces

Biotic invasions in the fossil record provide natural experiments for testing hypotheses of niche stability, speciation, and the assembly and diversity of regional biotas. We compare ecologic parameters (preferred environment, occupancy, median abundance, rank abundance) of genera shared between faunal provinces during the Richmondian Biotic Invasion in the Late Ordovician on the Laurentian continent. Genera that spread from one faunal province to the other during the invasion (invading shared genera) have high Spearman rank correlations (>0.5) in three of four ecologic parameters, suggesting a high level of niche stability among invaders. Genera that existed in both regions prior to and following the invasion (non-invading shared genera) have low correlations (<0.3) and suggest niche shift between lineages that diverged at least 8 Myr earlier. Niche shift did not accumulate gradually over this time interval, but appears to have occurred in a pulse associated with the onset of the Taconic orogeny and the switch from warm-water to cool-water carbonates in southern Laurentia

bighornc5_counts_PatzkowskyandHolland_2016_Paleobiology

This file contains the collection counts for the Ordovician Horseshoe Mountain Member in the Bighorn Mountains, Wyoming

sharedtaxa_ecol_param_PatzkowskyandHolland_2016_Paleobiology

This file contains the ecological parameters shared between the Horseshoe Mountain Member in the Bighorn Mountains, WY and the C5 sequence in the Cincinnatian type area

bighornc5_factors_PatzkowskyandHolland_2016_Paleobiology

This file contains the sample attributes for the Horseshoe Mountain Member collection counts

C5CincyCounts_PatzkowskyandHolland_2016_Paleobiology

This file contains the collection count data for the C5 sequence in the Cincinnatian type area

BIOMODULE: A Java program to help model and interpret the stratigraphic record

A combination of a stratigraphic simulation package (STRATA) and an evolutionary-ecological model (BIOSTRAT) can be used to simulate the distribution of species within a sequence stratigraphic framework. BIOMODULE is an extension of this model approach in that it facilitates the visualization and interpretation of those simulations and their input data. Environmental factors (e.g., sea-level changes or sedimentation rates) and ecological factors (preferred water depth, depth tolerance, abundance) that determine the spatial and temporal distribution of species are easily and quickly investigated. In addition, BIOMODULE can be used to compile the stratigraphic .rst and last appearances of those species and export them into available graphic correlation software packages (Conop9 and GraphCor). This can be used to test the graphic correlation technique and investigate its accuracy and precision under a range of different conditions (e.g., different stratigraphic architectures and sampling densities) since the true correlation of the different sections is already known. ́2002 Elsevier Science Ltd. All rights reserved

Rapid recovery from the Late Ordovician mass extinction

Understanding the evolutionary role of mass extinctions requires detailed knowledge of postextinction recoveries. However, most models of recovery hinge on a direct reading of the fossil record, and several recent studies have suggested that the fossil record is especially incomplete for recovery intervals immediately after mass extinctions. Here, we analyze a database of genus occurrences for the paleocontinent of Laurentia to determine the effects of regional processes on recovery and the effects of variations in preservation and sampling intensity on perceived diversity trends and taxonomic rates during the Late Ordovician mass extinction and Early Silurian recovery. After accounting for variation in sampling intensity, we find that marine benthic diversity in Laurentia recovered to preextinction levels within 5 million years, which is nearly 15 million years sooner than suggested by global compilations. The rapid turnover in Laurentia suggests that processes such as immigration may have been particularly important in the recovery of regional ecosystems from environmental perturbations. However, additional regional studies and a global analysis of the Late Ordovician mass extinction that accounts for variations in sampling intensity are necessary to confirm this pattern. Because the record of Phanerozoic mass extinctions and postextinction recoveries may be compromised by variations in preservation and sampling intensity, all should be reevaluated with sampling-standardized analyses if the evolutionary role of mass extinctions is to be fully understood