Shallow-Marine Crinoid Genera May Have Been More Resilient Across Permian Extinction Events in Terms of Richness Than Deep-Marine Crinoid Genera

Author

• Amelia C. Kolstad, Portland State UniversityFollow

First Advisor

John Bershaw

Date of Award

Spring 6-2026

Document Type

Thesis

Degree Name

Bachelor of Science (B.S.) in Geology and University Honors

Department

Geology

Language

English

Subjects

paleontology, geology, crinoid, crinoidea, bathymetry, marine

Abstract

Throughout the Phanerozoic, one of the most successful phyla of marine invertebrates has been Echinodermata. Echinodermata was particularly successful throughout the Paleozoic, with class Crinoidea making up a majority of occurrences. The proportion of echinoderm occurrences that are crinoids declined massively at the end of the Permian and continued to decrease into modern day, never fully recovering. One of the factors thought to have been so important for crinoid success in the Paleozoic and their decreasing success throughout geologic time has been their propensity for success in shallow-marine environments, though crinoids also exist within deep-marine environments. This study seeks to understand whether the richness of deep-marine or shallow-marine crinoids was more heavily affected by extinction events in the Permian period including the mid-Capitanian extinction, end-Capitanian extinction, and Permian-Triassic Mass Extinction (PTME), with a primary emphasis on the PTME. The results of this study suggest that shallow-marine crinoid genera had greater survivorship in terms of richness across the PTME boundary than deep-marine genera. While the specific mechanism for this disparity is not fully known, deep-marine ocean anoxia is a major potential cause.

Recommended Citation

Kolstad, Amelia C., "Shallow-Marine Crinoid Genera May Have Been More Resilient Across Permian Extinction Events in Terms of Richness Than Deep-Marine Crinoid Genera" (2026). University Honors Theses. Paper 1880.