58 Future Leaders in Paleontology

The Paleontological Society is pleased to offer the “Future Leaders in Paleontology” topical session. This session will showcase the outstanding work of our student and early career members in a high-profile setting.

Sunday, 19 October 2025
1:30 PM - 5:30 PM
HBGCC, 305

Did Harpiform Trilobites Evolve to Plow Sediment?: Finally Putting a 100-Year-Old Hypothesis to the Test

Paper number: 58-1
Program: Technical Sessions
Time: 1:35 PM – 1:50 PM

Authors

Abstract

During the Ordovician, trilobites of the order Harpetida and the superfamily Trinucleioidea evolved unusual cephalic brims, quite unlike any structure known in modern arthropods. Brimmed trilobites were broadly successful, but paleontologists still do not fully understand why the harpiform brim evolved or the role it played in their success. Many authors have speculated about the brim’s function, generating many untested hypotheses. We 3D-printed model cephalons with various brim shapes and moved them through natural sediments to test the hypothesis that the brim evolved as a sediment plow. We found that increased horizontal brim width allowed a cephalon to efficiently displace more sediment, while increased brim height merely impeded the cephalon’s progress. However, there is no clear evolutionary trend among harpetids or trinculeids towards wider or flatter brims, indicating that plowing did not exert a strong selective pressure on brimmed trilobites. This work also serves as a case study in researching taxa without modern biomechanical analogs, demonstrating that many functional hypotheses can be adequately tested by straightforward experimental methods.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6

doi: 10.1130/abs/2025AM-412736

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