Arctica medialis (Conrad, 1857)

Remarks

• Collector:    Keith Minor
• Formation:  Trinity Group, Glen Rose Formation
• Location:     Coryell County, TX

General Info

Synonyms (older names and misidentifications in the literature)

• 1857 Cardium medialis Conrad
• 1893 Cyprina medialis (Conrad); Cragin
• 1903 Isocardia medialis (Conrad); Shattuck
• 1928 Isocardia medialis (Conrad); Adkins
• 1928 Arctica mediale (Conrad); Adkins
• 1928 Cyprina medialis (Conrad); Vanderpool
• 1957 Isocardia medialis (Conrad); Hendricks
• 1960 Isocardia medialis (Conrad); Perkins
• 1967 Cyprina medialis (Conrad); Hendricks
• 1982 Arctica medialis (Conrad); Offeman et al.
• 1989 Arctica medialis (Conrad); Finsley

Stratigraphic Occurrence

• Uppermost Washita Group, Buda Formation of central Texas
• Fredericksburg Group, Goodland Formation of north Texas
• Fredericksburg Group, Comanche Peak Formation of north Texas
• Trinity Group, Upper Glen Rose Formation of north and central Texas.  It may extend down into the lower part of the formation.

Age

• Arctica medialis (Conrad) occurs from the Hypacanthoplites comalensis (Scott) zone to about the Budaiceras hyatti (Shattuck) zone, early Albian to early Cenomanian time (~108–97 mya).

Geographic Occurrence (not an all-inclusive list)

• Burnet County, TX
• Coryell County, TX
• Erath County, TX
• Gillespie County, TX
• Hood County, TX
• Jack County, TX
• Parker County, TX
• Travis County, TX

Remarks

For identification and descriptions, see:

• Offeman, I. D.; Ganshirt, R. H.; Lewis, P. C.; Martin, M., Jr.; Arnette, S. W.; Akers, R. E.; Akers, T. J.; Landry, R. M. 1982. Texas Cretaceous Bivalves and Localities. Texas Paleontology Series Publication 2. Houston: Paleontology Section, Houston Gem and Mineral Society.