Vexillum ctenotum is an extinct species of marine gastropod mollusk in the family Costellariidae, commonly known as the ribbed miters.[1] The species is known from fossil material collected in the Miocene Alum Bluff Formation of Florida, United States, and was first described by American paleontologist Julia Anna Gardner in 1937.[2]
Gardner described V. ctenotum in 1937 as part of her comprehensive monograph on the Alum Bluff molluscan fauna.[2] The genus Vexillum is widespread and diverse, characterized by elongated shells with axial ribs and spiral sculpture. V. ctenotum has been assigned to the family Costellariidae, a group of small to medium-sized predatory snails.
Description
The shell of V. ctenotum reaches a length of about 6mm.[2] It is small, slender, and elongate-fusiform, with axial costae (ribs) typical of the genus. Like other Vexillum species, the aperture is narrow and the outer lip is simple. Details of coloration are not preserved in fossils.
Distribution and paleoecology
Fossils of V. ctenotum are restricted to the Alum Bluff Formation in northern Florida.[2] The formation dates to the Miocene epoch (roughly 18–15 million years ago) and represents a shallow marine environment rich in molluscan faunas. V. ctenotum likely inhabited warm, shallow coastal waters as part of a diverse tropical to subtropical gastropod community.
Significance
The species is one of many described from the Alum Bluff Formation, which has provided important records of Miocene mollusks in the Gulf Coastal Plain. Gardner’s description of V. ctenotum contributed to the understanding of Miocene biodiversity and the evolutionary history of the family Costellariidae.
1 2 3 4 Gardner, Julia (1937). The Molluscan Fauna of the Alum Bluff Group of Florida, Part VI: Pteropoda, Opisthobranchia, and Ctenobranchia. U.S. Geological Survey Professional Paper 142-F.
Gardner, Julia. (1937). The Molluscan Fauna of the Alum Bluff Group of Florida, Part VI: Pteropoda, Opisthobranchia, and Ctenobranchia. U.S. Geological Survey Professional Paper 142-F. Washington, D.C.: Government Printing Office.
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