Pycnodonte (Phygraea) mutabilis (Morton, 1828)

Remarks

• Collector:    Prof. Norm King, University of Southern Indiana

• Formation:  Taylor Group, Marlbrook Marl

• Location:     Howard County, AR

General Info

Synonyms (older names and misidentifications in the literature)

• 1828 Gryphaea mutabilis Morton

• 1830 Gryphaea mutabilis Morton; Morton

• 1834 Gryphaea mutabilis Morton; Morton

• 1868 Pycnodonte vesicularis (Lamarck); Cook

• 1885 Gryphaea vesicularis Lamarck; Whitfield

• 1885 Gryphaea vesicularis var. mutabilis Morton; Whitfield

• 1900 Gryphaea vesicularis Lamarck; Harris

• 1902 Gryphaea vesicularis Lamarck; Taff

• 1905 Gryphaea mutabilis Morton; Johnson

• 1906 Gryphaea vesicularis Lamarck; Veatch

• 1906 Gryphaea vesicularis Lamarck; Böse

• 1907 Gryphaea mutabilis Morton; Weller

• 1916 Gryphaea (Pycnodonte) vesicularis (Lamarck); Gardner

• 1923 Gryphaea mutabilis Morton; Stephenson

• 1926 Gryphaea vesicularis Lamarck; Wade

• 1929 Gryphaea vesicularis Lamarck; Dane

• 1941 Gryphaea mutabilis Morton; Stephenson

• 1947 Gryphaea mutabilis Morton; Shimer & Shrock

• 1947 Gryphaea vesicularis Lamarck; Shimer & Shrock

• 1996 Gryphaea (Phygraea) mutabilis (Morton); Elder

Stratigraphic Occurrence

• Navarro Grp, Corsicana Mrl of north and central TX

• Navarro Grp, Kemp Clay of north TX

• Navarro Grp, Nacatoch Sand of north TX and southwestern AR

• Navarro Grp, Saratoga Chk of southwestern AR and LA

• Navarro Grp, Neylandville Mrl of northeast TX and southwestern AR

• Prairie Bluff Chalk of MS and AL

• Monmouth Grp, Severn Formation of MD

• Matawan Grp, Marshalltown Formation of DE and NJ

• Coon Creek Tongue of the Ripley Fm of TN

• Peedee Fm of NC and SC

• Taylor Grp, Pecan Gap Chk of north and central TX

• Taylor Grp, Marlbrook Mrl of northeast TX and southwest AR

• Taylor Grp, Bergstrom Mrl of central TX

• Taylor Grp, Ozan Mrl of northeast TX and southwestern AR

• Taylor Grp, Anacacho LS of south TX

• Demopolis Chk of TN, MS, and AL

• Coffee Sand of MS

• Stephenson indicated that the reports of P. (P.) mutabilis (Morton) from the Austin chalk are questionable since these specimens don't have the typical shape and thickness of the ones from the younger horizons.

Age

• If the reports from the Austin Group are excluded, Pycnodonte (Phygraea) mutabilis (Morton) ranges from the early Campanian to latest Maastrichtian Stage (to the end of Cretaceous, ~ 81–65 mya).

Geographic Occurrence (not an all-inclusive list)

• Alabama
• Bexar County, TX
• Bladen County, NC
• Bowie County, TX
• Burlington County, NJ
• Delta County, TX
• Hays County, TX
• Hempstead County, AR
• Howard County, AR
• Guadalupe County, TX
• Kinney County, TX
• Marion County, SC
• Maverick County, TX
• McNairy County, TN
• Medina County, TX
• New Castle County, DE
• Prince Georges County, MD
• Travis County, TX
• Uvalde County, TX

Remarks

         For identification, descriptions, and ranges, see:

• Stephenson, L. W.  1941.  The Larger Invertebrate Fossils of the Navarro Group of Texas (Exclusive of Corals and Crustaceans, and Exclusive of the Fauna of the Escondido Formation).  University of Texas Bulletin 4101, 115–117 and plate 17, figs 1–6.