Conacteon cadonensis

Conus cadonensis (Lyell & Sowerby in Lyell, 1840)

Conacteon cadonensis (Fischer & Weber, 1997)

Classe Gastropoda (Cuvier, 1797)

Sottoclasse Orthogastropoda (Ponder & Lindberg, 1996)

Superordine Heterobranchia (J. E. Gray, 1840)

Ordine Opisthobranchia (Milne-Edwards, 1848)

Descrizione e caratteristiche:

The oldest fossils described as Conus are from the Lias of Normandy near Caen; they are of Pliensbachian age (188-196 mybp; absolute dates in this paper are taken from Harland et al., 1982, and Haq & Van Eysinga, 1987) ⁽¹⁾.

Charles Lyell read an informal account of the discovery of these specimens in a publication of the Linnaean Society of Normandy ([Eudes-Deslongchamps], 1837). He collected

at the site in 1840, and later that year (Lyell,1840), in collaboration with G. B. Sowerby, he described Conus cadonensis and Conus concavus ⁽¹⁾.

Deshayes & Milne Edwards (1845:7) questioned the assignment of these species to Conus, and soon d'Orbigny (1850, 1852) confirmed their suspicion by demonstrating in sectioned specimens that the last whorls are thin and that internal shell walls are not resorbed.

In Conus, the last whorl is thick and inner walls are often reduced to 50 μm (Kohn et al., 1979), in Eocene as well as modern species (Kohn, 1982).

The name A. cadomensis is incorrect: it is found in: Chenu J.C. (1859-1862) «MANUEL DE CONCHYLIOLOGIE ET DE PALÉONTOLOGIE CONCHYLIOLOGIQUE»