Evaluating taxonomic turnover: Pennsylvanian–Permian brachiopods and bivalves of the North American Midcontinent

Abstract

Using museum and literature data, we characterize faunal turnover in bivalves and brachiopods of the North American Midcontinent over approximately 12.5 Myr spanning the Pennsylvanian/Permian boundary. The two groups experienced indistinguishable rates of background faunal turnover but differed in the type and timing of elevated turnover episodes. Bivalves underwent an episode of elevated first appearance in the Missourian Series whereas brachiopods underwent an episode of elevated disappearance in the Wolfcampian Series. In neither group does turnover history strongly correlate to long-term changes in basinal lithofacies, which reflect evolution of regional climate. Comparison with other time intervals and basins suggests that magnitude and frequency of turnover episodes during the late Paleozoic was intermediate between the more episodic early Paleozoic and less episodic Mesozoic.

The Pennsylvanian–Permian transition in the low-latitude carbonate record and the onset of major Gondwanan glaciation

“…Although the Pennsylvanian-Permian boundary in the Midcontinent is associated with a significant transgression event, several studies have documented a prolonged basinward shift in facies from the Red Eagle Limestone to the Beattie Limestone, which overlies the Eskridge Shale (West et al, 1997;Sawin et al, 2006). This claim has also been supported by studies of brachiopod assemblages, which suggest a dramatic loss in taxa due to shallowing of the basin (e.g., Cycle 29 of Olszewski and Patzkowsky, 2001). In general, there is an overall shallowing of facies that occurs throughout the Wolfcampian section of the Midcontinent.…”

Phylogenies and Community Ecology

“…The basic analysis of community phylogenetic structure requires only plot-based samples and a species list (which can be converted into a community supertree), and can thus be rapidly conducted on preexisting data. Where phylogenies can be constructed for fossils (e.g., Upchurch 1995, Vermeij & Carlson 2000 and a stratigraphic turnover of communities can be reconstructed (e.g., Olszewski & Patzkowsky 2001, Jackson & Overpeck 2000, change in community phylogenetic structure could be assessed over time.…”

Long-Term Stasis in Ecological Assemblages: Evidence from the Fossil Record

“…In addition, the frequency and magnitude of regional turnover episodes appear to decrease with time (Olszewski & Patzkowsky 2001). Whether this pattern will hold up to future scrutiny is not clear, but it does have implications for global Phanerozoic diversity patterns, which show decreasing rates of extinction and origination through time.…”

“…Such studies require a stratigraphie framework that allows correlation at levels finer than the time between turnover events (if these events occur in the study interval). One reason that three of the five cited studies in Table 2 , Holterhoff 1996, Olszewski & Patzkowsky 2001 come from the Carboniferous-Permian period is the strong stratigraphie cyclicity that characterizes these rocks. Despite some of the distinct differences in these studies, none refute the observation that biofacies are recurrent (even in the face of significant environmental change).…”

“…First, most studies do show times of elevated taxonomic turnover relative to background rates, although the rates themselves vary greatly. At least some studies (Tang & Bottjer 1996, Patzkowsky & Holland 1997, Olszewski & Patzkowsky 2001 show that episodes of elevated first appearance do not necessarily coincide with, or immediately follow, episodes of disappearance (as in Westrop 1996 andBrett &Baird 1995). In those studies that distinguished biofacies (Westrop 1996, Brett & Baird 1995, Olszewski & Patzkowsky 2001, the history of turnover appeared to differ between biofacies.…”