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Metoicoceras
Classification
Phylum:
Mollusca
Class:
Cephalopoda
Subclass:
Ammonoidea
Order:
Ammonitida
Suborder:
Ammonitina
Superfamily:
Acanthocerataceae
Family:
Acanthoceratidae
Subfamily:
Mammitinae
Formal Genus Name and Reference:
Metoicoceras HYATT, 1903, p. 115
Type Species:
Ammonites swallovi Shumard, 1860, p. 591, SD Shimer & SHROCK, 1944, p. 56
Images
(Click to enlarge in a new window)
Fig. 130, 1a, b. *M. swallovi (Shumard), Texas, a, X0.75, b, X0.5 (Hyatt, 1903).
Synonyms
Geographic Distribution
Europe, northern and western Africa, Madagascar, Israel, Iran, southern India, USA, Peru, Brazil
Age Range
Beginning Stage in Treatise Usage:
Upper Cretaceous (upper Middle Cenomanian)
Beginning International Stage:
Cenomanian
Fraction Up In Beginning Stage:
50
Beginning Date:
97.2
Ending Stage in Treatise Usage:
Upper Cretaceous (middle Upper Cenomanian)
Ending International Stage:
Cenomanian
Fraction Up In Ending Stage:
100
Ending Date:
93.9
Description
Venter on phagmocone flat, on body chamber generally rounded; ribs straight to slightly flexuous, tending to become flat on outer part of sides; inner and outer ventrolateral tubercles present, former weakening and disappearing before end of phragmocone. Macroconchs tending to be more involute and feebly ornamented and microconchs more evolute and strongly ornamented. Differs from its presumed ancestor Plesiocanthoceras mainly in its simpler suture, pseudoceratitic in some, and absence of row of siphonal tubercles (except on early whorls of earliest species). Includes smooth or ribbed, compressed, involute forms and coarsely ornamented, evolute forms.
References
Museum or Author Information
Classification
Phylum:
Mollusca
Class:
Cephalopoda
Subclass:
Ammonoidea
Order:
Ammonitida
Suborder:
Ammonitina
Superfamily:
Acanthocerataceae
Family:
Acanthoceratidae
Subfamily:
Mammitinae
Formal Genus Name and Reference:
Metoicoceras HYATT, 1903, p. 115
Type Species:
Ammonites swallovi Shumard, 1860, p. 591, SD Shimer & SHROCK, 1944, p. 56
Images
(Click to enlarge in a new window)
Fig. 130, 1a, b. *M. swallovi (Shumard), Texas, a, X0.75, b, X0.5 (Hyatt, 1903).
Synonyms
Geographic Distribution
Europe, northern and western Africa, Madagascar, Israel, Iran, southern India, USA, Peru, Brazil
Age Range
Beginning Stage in Treatise Usage:
Upper Cretaceous (upper Middle Cenomanian)
Beginning International Stage:
Cenomanian
Fraction Up In Beginning Stage:
50
Beginning Date:
97.2
Ending Stage in Treatise Usage:
Upper Cretaceous (middle Upper Cenomanian)
Ending International Stage:
Cenomanian
Fraction Up In Ending Stage:
100
Ending Date:
93.9
Description
Venter on phagmocone flat, on body chamber generally rounded; ribs straight to slightly flexuous, tending to become flat on outer part of sides; inner and outer ventrolateral tubercles present, former weakening and disappearing before end of phragmocone. Macroconchs tending to be more involute and feebly ornamented and microconchs more evolute and strongly ornamented. Differs from its presumed ancestor Plesiocanthoceras mainly in its simpler suture, pseudoceratitic in some, and absence of row of siphonal tubercles (except on early whorls of earliest species). Includes smooth or ribbed, compressed, involute forms and coarsely ornamented, evolute forms.