Nicaisolopha bellaplicata (Shumard, 1860)

Remarks

• Collector:    Keith Minor

• Formation:  Eagle Ford Group, Arcadia Park Shale

• Location:     Dallas County, Texas.

General Info

Synonyms (older names and misidentifications in the literature)

• 1860 Ostrea bellaplicata Shumard

• 1860 Alectryonia bellaplicata Shumard

• 1857 Alectryonia lugubris (Conrad), in part

• 1982 Lopha bellaplicata bellaplicata (Shumard); Offeman et al.

Stratigraphic Occurrence

• Upper Eagle Ford Group, Arcadia Park Formation of North Texas

• Upper Eagle Ford Group, Arcadia Park Formation, Bells Sandstone Member of Northeast Texas

• Benton Group, Carlile Shale, Codell Sandstone Member of Colorado

• In Dallas County, TX N. bellaplicata (Shumard) forms the contact between the Eagle Ford and overlying Austin Groups.

• Along the Red River (TX-OK Border) an intervening 10 feet of Eagle Ford Group (Maribel Shale) occurs between the N. bellaplicata (Shumard) zone (and L. lugubris (Conrad)) and the contact between the Eagle Ford and Austin Groups.

Age

• Nicaisolopha bellaplicata belliplicata (Shumard) ranges within the Prionocyclus hyatti (Stanton) zone, late Middle Turonian (~90 mya) in the Western Interior.  
• In Texas, the oyster beds formed by N. bellaplicata (Shumard) seem to range into the L. lugubris (Conrad) zone, lower Upper Turonian.  Instead, this may be an artifact of lower sedimentation rates in the Dallas area, as compared to the rates farther North.

Geographic Occurrence (not an all-inclusive list)

• Dallas County, TX

• Grayson County, TX

• Pueblo County, CO

Remarks

         For identification and descriptions, see:

• Kauffman, E. G.  1977.  “Illustrated Guide to Biostratigraphically Important Macrofossils, Western Interior Basin, U. S. A.”.  In:  Kauffman, E. G., ed.  Field Guide:  North American Paleontological Convention II.  Cretaceous Facies, Faunas, and Paleoenvironments Across the Western Interior Basin.  The Mountain Geologist 14 (3–4), 225–274.