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Eoplacognathus
Classification
Phylum:
Conodonta
Class:
Conodonta
Order:
Conodontophorida
Superfamily:
Prioniodontacea
Family:
Polyplacognathidae
Formal Genus Name and Reference:
Eoplacognathus HAMAR, 1966, p. 52
Type Species:
Ambalodus lindstroemi HAMAR, 1964, p. 258, OD
Images
(Click to enlarge in a new window)
Fig. 79, 1. E. foliaceus (FÅhraeus), M.Ord. (Folkeslunda Ls.), Eu. (Sweden), la-c, stelliplanate element, lower, upper, lat. views, 1 d e, sinistral pastiniplanate element, upper, lower views, 1 f, g, dextral pastiniplanate element, lower, upper views, X50 (Bergström, n).
Synonyms
Priomorphognathus
Geographic Distribution
L.Ord.-M.Ord., Eu. (Baltoscandia-Pol.-G. Brit.-USSR-Irc.)-N. Am. (Appalachian Mts.-Great Basin-Okla.-Ark.)
Age Range
Beginning Stage in Treatise Usage:
L.Ord.
Beginning International Stage:
Tremadocian
Fraction Up In Beginning Stage:
0
Beginning Date:
486.85
Ending Stage in Treatise Usage:
M.Ord.
Ending International Stage:
Darriwilian
Fraction Up In Ending Stage:
100
Ending Date:
458.18
Description
Apparatus composed of Pa and Pb elements but left and right elements in each pair not mirror images, morphologically distinct. Pa elements stelliplanate with an anterior process, in some bladelike, a posterior process, and 2 to 3 lateral processes, one lateral process bifid in some. Pb elements pastiniplanate, Y -shaped, with long anterior process bladelike in some distally, short posterior process forming angle with anterior process, and short lateral process departing from point of junction between anterior and posterior processes, some elements with short cusp at this junction. Single row of relatively low denticles centrally located on each process of all elements; no additional denticle rows or nodes present laterally. [Elements of Eoplacognathus are distinguished from corresponding ones in Polyplacognathus, with which they have been confused frequently, by their lack of accessory denticulation lateral to the central denticle rows and by process configuration; further, right and left elements in each pair in Polyplacognathus are near mirror images and not different as in Eoplacognathus. Apparatus reconstruction: BERGSTROM, 1971, 1973.]
References
Museum or Author Information
Classification
Phylum:
Conodonta
Class:
Conodonta
Order:
Conodontophorida
Superfamily:
Prioniodontacea
Family:
Polyplacognathidae
Formal Genus Name and Reference:
Eoplacognathus HAMAR, 1966, p. 52
Type Species:
Ambalodus lindstroemi HAMAR, 1964, p. 258, OD
Images
(Click to enlarge in a new window)
Fig. 79, 1. E. foliaceus (FÅhraeus), M.Ord. (Folkeslunda Ls.), Eu. (Sweden), la-c, stelliplanate element, lower, upper, lat. views, 1 d e, sinistral pastiniplanate element, upper, lower views, 1 f, g, dextral pastiniplanate element, lower, upper views, X50 (Bergström, n).
Synonyms
Priomorphognathus
Geographic Distribution
L.Ord.-M.Ord., Eu. (Baltoscandia-Pol.-G. Brit.-USSR-Irc.)-N. Am. (Appalachian Mts.-Great Basin-Okla.-Ark.)
Age Range
Beginning Stage in Treatise Usage:
L.Ord.
Beginning International Stage:
Tremadocian
Fraction Up In Beginning Stage:
0
Beginning Date:
486.85
Ending Stage in Treatise Usage:
M.Ord.
Ending International Stage:
Darriwilian
Fraction Up In Ending Stage:
100
Ending Date:
458.18
Description
Apparatus composed of Pa and Pb elements but left and right elements in each pair not mirror images, morphologically distinct. Pa elements stelliplanate with an anterior process, in some bladelike, a posterior process, and 2 to 3 lateral processes, one lateral process bifid in some. Pb elements pastiniplanate, Y -shaped, with long anterior process bladelike in some distally, short posterior process forming angle with anterior process, and short lateral process departing from point of junction between anterior and posterior processes, some elements with short cusp at this junction. Single row of relatively low denticles centrally located on each process of all elements; no additional denticle rows or nodes present laterally. [Elements of Eoplacognathus are distinguished from corresponding ones in Polyplacognathus, with which they have been confused frequently, by their lack of accessory denticulation lateral to the central denticle rows and by process configuration; further, right and left elements in each pair in Polyplacognathus are near mirror images and not different as in Eoplacognathus. Apparatus reconstruction: BERGSTROM, 1971, 1973.]