Pteroperna kitadaniensis Goto, 1983

Distribution: 

"Black mudstone at the lower (?) Pliensbachian Negoya Formation of the Kitadani, Asahi-machi, Shimoniikawa-gun, Toyama Prefecture." [Goto, 1983: 83.]

Geological age: 

Lower (?) Pliensbachian, Lower Jurassic [Goto, 1983].

Description: 

"Shell is small, inequivalve, pteriform, left valve more strongly convex than right. Hinge-margin is straight, fairly long. Anterior wing is large, triangular in right valve, subtriangular with a rounded anterior extremity in left valve. Posterior wing with three longitudinal ridges is long, sharply pointed backwards, with remarkably sinuated posterior margin; umbo located at about a fifth of hinge-line from anterior end, fairly protruded above hinge-margin in left valve, but not in right; surface marked with fluctuated concentric lamellae." [Goto, 1983: 83.]

Type material illustration: 

Goto, 1983: pl. 15, fig. 3, 4.

Typification: 

Holotype: P.31102, internal and external molds of LV; paratype: P.1102, nternal and external molds of RV. [Goto, 1983: 83.]

Thu, 2007-12-13 20:55 -- ilya
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Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith