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Peritrochia
Classification
Phylum:
Mollusca
Class:
Cephalopoda
Subclass:
Ammonoidea
Order:
Goniatitida
Suborder:
Goniatitina
Superfamily:
Cycloloboidea
Family:
Vidrioceratidae
Formal Genus Name and Reference:
Peritrochia GIRTY, 1908, p. 498
Type Species:
P. erebus, M
Images
(Click to enlarge in a new window)
Fig. 90, 3a-d. *P. erebus, upper Cutoff Formation, topotypes, a, SUI 32586, X 2, b-c, SUI 32585, X 2 (new), d, diameter at 11 mm (Miller & Furnish, 1940a).
Synonyms
Geographic Distribution
USA (western Texas)
Age Range
Beginning Stage in Treatise Usage:
Guadalupian (Roadian)
Beginning International Stage:
Roadian
Fraction Up In Beginning Stage:
0
Beginning Date:
274.37
Ending Stage in Treatise Usage:
Guadalupian (Roadian)
Ending International Stage:
Roadian
Fraction Up In Ending Stage:
100
Ending Date:
269.21
Description
Conch small (mature diameter 2 cm), with biconvex growth lines. Mature modifications comprise subterminal constriction and subsequent flare (expansion) of peristome, and formation of a pair of broad ventrolateral lappets bounding an accentuated hyponomic sinus. Suture is characterized by undivided prongs of ventral lobe (V1 ) and a dorsal lobe (D) that lacks division in all growth stages. Sutural formula: (V1 V1 )L2 L1 L2.1 L2.1 U2 U1 :U2 I2.1 I2.1 I1 I2 D [Russian]. One species. [The origin of the fourth external lobe and fourth internal lobe (L 2.1 and I2.1 ) through subequal bifurcation of the third laterals (L 2 and I2 ) relates Peritrochia to the Vidrioceratidae rather than to the Marathonitidae.]
References
Museum or Author Information
Classification
Phylum:
Mollusca
Class:
Cephalopoda
Subclass:
Ammonoidea
Order:
Goniatitida
Suborder:
Goniatitina
Superfamily:
Cycloloboidea
Family:
Vidrioceratidae
Formal Genus Name and Reference:
Peritrochia GIRTY, 1908, p. 498
Type Species:
P. erebus, M
Images
(Click to enlarge in a new window)
Fig. 90, 3a-d. *P. erebus, upper Cutoff Formation, topotypes, a, SUI 32586, X 2, b-c, SUI 32585, X 2 (new), d, diameter at 11 mm (Miller & Furnish, 1940a).
Synonyms
Geographic Distribution
USA (western Texas)
Age Range
Beginning Stage in Treatise Usage:
Guadalupian (Roadian)
Beginning International Stage:
Roadian
Fraction Up In Beginning Stage:
0
Beginning Date:
274.37
Ending Stage in Treatise Usage:
Guadalupian (Roadian)
Ending International Stage:
Roadian
Fraction Up In Ending Stage:
100
Ending Date:
269.21
Description
Conch small (mature diameter 2 cm), with biconvex growth lines. Mature modifications comprise subterminal constriction and subsequent flare (expansion) of peristome, and formation of a pair of broad ventrolateral lappets bounding an accentuated hyponomic sinus. Suture is characterized by undivided prongs of ventral lobe (V1 ) and a dorsal lobe (D) that lacks division in all growth stages. Sutural formula: (V1 V1 )L2 L1 L2.1 L2.1 U2 U1 :U2 I2.1 I2.1 I1 I2 D [Russian]. One species. [The origin of the fourth external lobe and fourth internal lobe (L 2.1 and I2.1 ) through subequal bifurcation of the third laterals (L 2 and I2 ) relates Peritrochia to the Vidrioceratidae rather than to the Marathonitidae.]