Paleocommunity composition, relative abundance, and new camerate crinoids from the Brechin Lagerstätte (Upper Ordovician)

Abstract

The Brechin Lagerstätte of southern Ontario contains an exceptionally diverse and well-preserved Late Ordovician (Katian) crinoid fauna. We describe four genera and eight species of camerate crinoids from the Brechin Lagerstätte, including six new species. Consequently, the total diversity of the fauna now stands at 27 genera and 39 nominal species, thereby making it the most taxonomically diverse Ordovician crinoid fauna known. Taxa described include the diplobathrid Pararchaeocrinus kiddi new species and the monobathrids Glyptocrinus ramulosus Billings, 1856, Periglyptocrinus priscus (Billings, 1857a), Periglyptocrinus astricus new species, Periglyptocrinus kevinbretti new species, Periglyptocrinus mcdonaldi new species, Periglyptocrinus silvosus new species, and Abludoglyptocrinus steinheimerae new species. We summarize the taxonomic composition, diversity, and abundance distribution of all known crinoids from the Brechin Lagerstätte to better characterize the paleoecological structure and complexity of the community. We establish that the fauna is dominated by the subclass Pentacrinoidea, both in terms of abundance and species richness. In addition, we analyze species-level abundance data using Relative Abundance Distribution (RAD) models to evaluate the ecological complexity of the paleocommunity. We found that community structure of the Brechin Lagerstätte is best explained by an ecologically ‘complex’ RAD model, which suggests that species partitioned niches along multiple resource axes and/or the presence of multiple ecological ways of life. These results indicate that the Brechin Lagerstätte is significant not only for being the most taxonomically diverse Katian crinoid assemblage, but also for being an early ecologically complex fauna that developed in the wake of the Great Ordovician Biodiversification Event. UUID: http://zoobank.org/f86582ed-5db6-469E-befe-34b801f9a113

Niche evolution and phylogenetic community paleoecology of Late Ordovician crinoids

“…As a result, both paleocommunities should be broadly representative of Laurentian crinoid faunas during these stages of the Upper Ordovician. For example, the relative proportions of major groups that make up the Brechin fauna are comparable to those of other Katian-age crinoid assemblages (Cole et al, 2017;Cole et al, 2020).…”

“…Peak genus-level diversity was reached during the Katian stage of the Upper Ordovician before it dropped precipitously during the Late Ordovician mass extinction across the Katian-Hirnantian boundary (Peters & Ausich, 2008;Wright & Toom, 2017;Cole, 2018). The rapid increase in crinoid genus and species diversity led to greater morphological and ecological variation during Upper Ordovician (Foote, 1994(Foote, , 1999Deline & Ausich, 2011;Wright, 2017a;Deline et al, 2018Deline et al, , 2020Cole & Hopkins, 2021) and increases in community complexity (Cole et al, 2020). As a result, the Upper Ordovician is dynamic interval of time in crinoid evolutionary history that is ideal for evaluating the evolution of niche occupation and community assembly in early crinoid communities.…”

“…At the ecosystem scale, a variety of approaches have been used to evaluate broad patterns of resource utilization, functional diversity, and complexity through deep time using theoretical concepts and methodological approaches like tiering, ecospace filling, limiting components, ecosystem engineering, ecological clustering, network analysis, niche modeling, and abundance distributions (e.g., Ausich, 1983;Bambach, 1983;Ausich & Bottjer, 1986;Wagner et al, 2006;Bambach et al, 2007;Erwin, 2008;Novack-Gottshall, 2007;Stigall, 2012;Dineen et al, 2014;Muscente et al, 2018). Many of these methods have also been successfully applied to community-level investigations to evaluate various aspects of ecology or make comparisons between paleocommunities (e.g., Brame & Stigall, 2014;Darroch et al, 2018;Perera and Stigall, 2018;Whittle et al, 2019;Cole et al, 2020;Nanglu et al, 2020). However, other ecological aspects of paleocommunities relating to niche partitioning, assembly, and structure are not readily captured by these methods and have received far less attention in past studies, particularly for clades of fossil marine invertebrates.…”

“…Although these methods are more rarely applied to invertebrate fossil groups (e.g., Cole et al, 2019;Chang & Skipwith, 2020), fossil crinoids are a particularly promising system because they preserve extensive ecological data and have a robust phylogenetic framework Cole et al, 2019). As a result, they are the only fossil invertebrate group for which community-level niche dynamics have been studied in a phylogenetic context (Cole et al, 2019;Cole et al, 2020), and have the potential to provide deep-time perspectives on niche evolution, niche dynamics, and community ecology.…”

A Hirnantian holdover from the Late Ordovician mass extinction: phylogeny and biogeography of a new anthracocrinid crinoid from Estonia

“…We coded Tallinnicrinus for the same 135 discrete morphological characters used in the analysis of Cole (2018) and pruned the matrix to include only Ordovician – early Silurian genera, which produced a phylogenetic matrix with a total of 55 taxa (Cole et al . 2020b). Although pruning taxa that are middle Silurian or younger from the matrix could affect phylogenetic results, the matrix still includes all major lineages of diplobathrids and all known diplobathrid genera occurring c .…”