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New Lower Mississippian Trilobites from the Chouteau Group of Missouri

Annals of Carnegie Museum

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Abstract

Reexamination of existing trilobite collections from the Kinderhookian (Lower Mississippian) Chouteau Group of central and northeastern Missouri indicates that two different suites of trilobites are present in these two areas of the state. Moreover, the study of these collections has led to the erection of a new genus and four new species. The new genus, Ameropiltonia, is based on a new species, A. lauradanae. This genus and species is commonly confused with Breviphillipsia sampsoni (Vogdes). Elliptophillipsia rotundus, n. sp., differs from the type species of this genus by possessing a rounded frontal lobe to the glabella. The other new species, Perexigupyge chouteauensis and Richterella hessleri, are present in the Compton Limestone of Marion and Ralls counties of northeastern Missouri. Variations in trilobite species found in the Compton Limestone of central Missouri and the northeastern part of the state are interpreted to be environmentally related. It appears that the lime mudstone and wackestone lithologies characteristic of the Compton Limestone of central Missouri were deposited in a low-energy, subtidal shelf setting. The lime packstone-grainstone strata of northeastern Missouri are interpreted to have formed as a tidal sand belt on the eastern margin of the Burlington shelf.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
New Lower Mississippian Trilobites from the Chouteau Group of Missouri
Series title:
Annals of Carnegie Museum
Volume
69
Issue:
2
Year Published:
2000
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Annals of Carnegie Museum
First page:
135
Last page:
144
Number of Pages:
10