178-11 Complex Morphological Variation Within the Trilobite Celtencrinurus laurentinus (Twenhofel, 1928), Based on Newly Discovered Specimens from Anticosti Island, Québec.

Session: Paleontology, Diversity, Extinction, Origination

Presenting Author:

Authors:

Abstract:

The fossil record on Anticosti Island, Québec, Canada, extends from the Katian (Late Ordovician) to the Telychian (Llandovery) and preserves shallow marine invertebrate faunas throughout. Of the trilobites, those of Silurian age have historically drawn the attention of many collectors and researchers for their abundance and exceptional preservation. In contrast, those of Ordovician age are much less well known with almost no taxonomic work since Twenhofel’s monograph from 1928. Recent field expeditions to Late Ordovician sites of Anticosti Island have yielded new material, among them, the first complete specimens of the encrinurid trilobite; Celtencrinurus laurentinus (Twenhofel, 1928). Close examination of these specimens and existing collections at the Yale Peabody Museum has revealed a great degree of morphological variation within and between two distinct morphotypes which overlap in geographic and temporal range, raising questions about whether the morphotypes are better interpreted to be sexual dimorphs or ecomorphotypes of a single species or two distinct species. In addition, morphological variation that is exhibited by the Anticosti specimens may have broader implications on our understanding of evolution of the Celtencrinurus multisegmentatus species group.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-7160

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