Jennifer E. Bauer

Phylogenetic paleobiogeography of Late Ordovician Laurentian brachiopods

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.

A combined morphometric and phylogenetic revision of the Late Ordovician brachiopod genera Eochonetes and Thaerodonta

Abstract. Systematic revision of the Late Ordovician brachiopod genera Eochonetes Reed, 1917 and Thaerodonta Wang, 1949 was conducted utilizing specimen-based morphometric and species-level phylogenetic analyses. Previous studies had recognized Thaerodonta and Eochonetes as either distinct taxonomic entities or synonyms. New multivariate and phylogenetic analyses confirm the synonymy of Thaerodonta with Eochonetes and provide a framework to assess evolutionary and ecological patterns within the clade. Multivariate analyses were employed to delineate species in morphospace and provided information on potential species relationships. Phylogenetic analysis was used to produce an evolutionary framework for taxonomic revision and identify character evolution within the clade. Most species previously assigned to Thaerodonta are transferred to Eochonetes, and three others are excluded from Eochonetes and provisionally referred to other sowerbyellid genera. Three new species (Eochonetes maearum new species, E. voldemortus new species, E. minerva new species) are described, one species (Leptaena saxea Sardeson, 1892) is synonymized with E. recedens Sardeson, 1892, and one subspecies (Thaerodonta mucronata scabra Howe, 1965) is rejected. This study demonstrates that a combination of complementary approaches and data types has the potential to advance interpretations beyond analyses confined to single analytical tools. Specifically, multivariate analyses provide constraints on species boundaries, whereas species-level phylogenetic analyses provide frameworks to examine morphological, ecological, and biogeographic evolution within a clade.

Hydrospire morphology and implications for blastoid phylogeny

Abstract. The external expression of hydrospires in blastoids has provided a basis for major and minor group classification in the clade for over a century. Unfortunately, the complete anatomy of the hydrospires has never been comprehensively studied. This study examined and described the internal hydrospires of six spiraculate species by digitally extracting hydrospire data from a legacy data set of serial acetate peels. Although only six models have been currently generated, hydrospire morphology is variable both within and between previously described spiraculate families. Hydrospires were found to possess novel characters that were incorporated into a phylogenetic analysis of the six digitally modeled species and several related species. The addition of internal morphology into the phylogenetic analysis provides further resolution between groupings of blastoids.

Darwin Day in deep time: promoting evolutionary science through paleontology

Charles Darwin’s birthday, February 12th, is an international celebration coined Darwin Day. During the week of his birthday, universities, museums, and science-oriented organizations worldwide host events that celebrate Darwin’s scientific achievements in evolutionary biology. The University of Tennessee, Knoxville (UT) has one of the longest running celebrations in the nation, with 2016 marking the 19th year. For 2016, the theme for our weeklong series of events was paleontology, chosen to celebrate new research in the field and to highlight the specific misconceptions of evolution within the context of geologic time. We provide insight into the workings of one of our largest and most successful Darwin Day celebration to date, so that other institutions might also be able to host their own rewarding Darwin Day events in the future.