September 2021 Virtual Meeting

Monday, September 13, 2021
6:00 - 7:30 pm

Note: ETGS members will receive an email with info for logging into the meeting.

September Presentation

A New Look at Mississippian Brittle Star Diversity Based on Disarticulated Skeletal Elements



Dr. Colin D. Sumrall
Associate Professor Paleobiology
Department of Earth and Planetary Sciences
University of Tennessee, Knoxville


Following the Devonian Mass extinction and the global collapse of reef systems, echinoderms (starfish, sea urchins and their relatives) diversified into the Carboniferous during a time termed the Age of Crinoids. Expansions in diversity are noted in many echinoderm groups including crinoids, blastoids, echinoids, and edrioasteroids, but brittle star records for this interval are few and far between as they rely on specimens collected from extraordinary fossil occurrences. New study methodologies developed for Mesozoic and Cenozoic taxa demonstrated that brittle star lateral arm plates (LAP) are morphologically diverse and diagnostic, and are reliable for identifying species from disarticulated material. Pilot studies in the Upper Mississippian and Lower Pennsylvanian demonstrated that brittle stars are abundant as disarticulated material and extremely diverse during this interval - up to 15 species per fauna - and have the highest generic diversity known in the Paleozoic. These faunas also include taxa belonging to both ancient taxa, such as stenuroids, previously thought to have gone extinct during the Devonian, as well as modern brittle star groups that diversified after the Permian mass extinction, showing that the post Permian expansion was well underway some 50 million years earlier. This study documents this post Devonian expansion into the Carboniferous by generating a better framework for understanding LAP morphologies and variation in Paleozoic taxa, and documenting brittle star species stratigraphically to better interpret temporal changes in brittle star diversity. Ultimately we plan to combine the taxonomic and phylogenetic structure of brittle stars to examine how diversity changes in the run up to, and just after the Permian mass extinction.


Dr. Sumrall has been at the University of Tennessee Department of Earth and Planetary Sciences since 2001, first as a lecturer and currently as an Associate Professor. Colin teach various courses on fossils and sedimentology.  Dr. Sumrall's research is centered on understanding the paleobiology of extinct echinoderms (starfish and their allies). His research is phylogenetically oriented, and echinoderms lend themselves to this approach because their intricate morphology, coupled with a high degree of morphological disparity, allow coding of robust datasets for phylogenetic analysis. Dr. Sumrall's work focuses primarily on Cambrian and Ordovician echinoderm radiations globally. Colin's professional background and affiliations include:

  • PhD University of Texas at Austin, 1996

  • Former Curator of Invertebrate Paleontology at the Cincinnati Museum Center

  • Editor and Chief of Elements of Paleontology, Cambridge University Press

  • GSA Southeastern Section President 2019-2020

  • Author of over 100 scholarly articles on fossil echinoderms




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Page updated September 13, 2021