
Origin, evolution and systematics of the Cretaceous ammonoid Spathites
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Spathites Kummel and Decker, 1954. a predominantly early to mid-Turonian genus common in Tethyan regions of both the Old and New Worlds, is a key genus in the early radiation of the Mammitinae (of which the Metoicoceratinae and Fallotitinae are shown to be synonyms). Spathitoides Wiedmann, I960 is a strict synonym and Jeanrogericeras Wiedmann, 1960 (of which Faltotites Wiedmann, i960 is a synonym) no more than subgenerically distinct. The genus evolved from Metoicoceras; a succession is demonstrated from S. (Jeanrogericeras) to S. (Spathites). Mammites is an early offshoot from the former subgenus, whilst the Coniacian Buchiceras, previously referred to the Tissotiidae, is a direct descendant of the S. (S.)rioensis Powell to S. (S.) chispaensis Kummel and Decker to S. (5.) puercoensis (Herrick and Johnson) lineage.
Palaeontology - Volume 23 Part 4 Pages 821-837Palaeontology - Volume 23 Part 4 Pages 821-837
Citations
KENNEDY, W. J., WRIGHT, C. W., HANCOCK, J. M. 1980. Origin, evolution and systematics of the Cretaceous ammonoid Spathites. Palaeontology, 23, 4, 821–837.