Document Type
Article
Publication Date
2019
College/Unit
Eberly College of Arts and Sciences
Department/Program/Center
Geology and Geography
Abstract
Background
Chasmataspidids are a rare group of chelicerate arthropods known from 12 species assigned to ten genera, with a geologic range extending from the Ordovician to the Devonian. The Late Ordovician (Richmondian) fauna of the Big Hill Lagerstätte includes a new species of chasmataspidid represented by 55 specimens. This taxon is only the second chasmataspidid described from the Ordovician and preserves morphological details unknown from any of the previously described species.
Results
The new chasmataspidid species is described as Hoplitaspis hiawathai gen. et sp. nov.. Comparison with all other known chasmataspidids indicates that Hoplitaspisoccupies an intermediate morphological position between the Ordovician Chasmataspis and the Silurian-Devonian diploaspidids. While the modification of appendage VI into a broad swimming paddle allies Hoplitaspis to the Diploaspididae, the paddle lacks the anterior ‘podomere 7a’ found in other diploaspidids and shows evidence of having been derived from a Chasmataspis-like chelate appendage. Other details, such as the large body size and degree of expression of the first tergite, show clear affinities with Chasmataspis, providing strong support for chasmataspidid monophyly.
Conclusions
The large body size and well-developed appendage armature of Hoplitaspis reveals that chasmataspidids occupied a greater breadth of ecological roles than previously thought, with the abundance of available specimens indicating that Hoplitaspis was an important component of the local community. The miniaturization and ecological limiting of diploaspidids potentially coincides with the major radiation of eurypterids and may suggest some degree of competition between the two groups. The geographic distribution of chasmataspidid species suggests the group may have originated in Laurentia and migrated to the paleocontinents of Baltica and Siberia as tectonic processes drew the paleocontinents into close proximity.
Digital Commons Citation
Lamsdell, James C.; Gunderson, Gerald O.; and Meyer, Ronald C., "A common arthropod from the Late Ordovician Big Hill Lagerstätte (Michigan) reveals an unexpected ecological diversity within Chasmataspidida" (2019). Faculty & Staff Scholarship. 2357.
https://researchrepository.wvu.edu/faculty_publications/2357
Source Citation
Lamsdell, J.C., Gunderson, G.O. & Meyer, R.C. A common arthropod from the Late Ordovician Big Hill Lagerstätte (Michigan) reveals an unexpected ecological diversity within Chasmataspidida. BMC Evol Biol 19, 8 (2019). https://doi.org/10.1186/s12862-018-1329-4
Comments
Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.