Phylogenetic paleobiogeography of Late Ordovician Laurentian brachiopods; pp. 189–194

A L Stigall,J E Bauer

doi:10.3176/earth.2014.17

Abstract

Phylogenetic biogeographic analysis of four brachiopod genera was used to uncover large-scale geologic drivers of Late Ordovician biogeographic differentiation in Laurentia. Previously generated phylogenetic hypotheses were converted into area cladograms, ancestral geographic ranges were optimized and speciation events characterized as via dispersal or vicariance, when possible. Area relationships were reconstructed using Lieberman-modified Brooks Parsimony Analysis. The resulting area cladograms indicate tectonic and oceanographic changes were the primary geologic drivers of biogeographic patterns within the focal taxa. The Taconic tectophase contributed to the separation of the Appalachian and Central basins as well as the two midcontinent basins, whereas sea level rise following the Boda Event promoted interbasinal dispersal. Three migration pathways into the Cincinnati Basin were recognized, which supports the multiple pathway hypothesis for the Richmondian Invasion.

Highlights

Species immigration and dispersal events are common in the fossil record
We examine a specific episode of interbasinal species invasion, the Richmondian Invasion, which is recorded in the Katian age strata of the Cincinnatian Series in the Cincinnati, USA region
Of the focal clades examined in this chapter, three species migrated into the Cincinnati Basin during the Richmondian Invasion from three different ancestral areas: the paleoequatorial region north of the Transcontinental Arch, the midcontinent region and a peripheral basin (Fig. 1B)

Summary

Introduction

Species immigration and dispersal events are common in the fossil record. The Richmondian Invasion records an immigration of over 60 genera into the Cincinnati region, including members of orders which had been absent from the region for at least 5 million years (Holland 1997; Stigall 2010). Invasive taxa included members of all trophic levels from pelagic predators to sessile benthos. The introduction of these new taxa caused a fundamental rearrangement of the community structure which had been stable for nearly 5 million years before the invasion (Patzkowsky & Holland 2007) and resulted in niche evolution among both native and incumbent species (Brame & Stigall 2014)

Objectives

Methods

Results

Discussion

Conclusion