Natica aff. collina Conrad, 1857

Remarks

• Collector:      Keith Minor

• Formation:    Fredericksburg Group, Bee Caves Limestone (= Upper Walnut Clay)

• Location:       Travis County, TX

• Dimensions:   lt = 20 mm, diam at widest part = 17 mm

• It's not clear to us why this has been moved to the genus Ampullina, since Conrad's holotype doesn't show enough features to separate this species from the genus Natica.  We have several specimens, and they all compare well with Conrad's holotype.  We're siding with Conrad's original diagnosis.

• Natica collina Conrad essentially looks like a miniature version of a Lunatia.

General Info

Synonyms (older names and misidentifications in the literature)

• 1857 Natica collina Conrad
• 1910 Natica aff. collina Conrad; Böse
• 1928 Ampullina (?) collina (Conrad); Adkins
• 1970 Natica sp. cf. collina Conrad; Smith
• 1997 Ampullina (?) collina (Conrad, 1857); Akers & Akers

Stratigraphic Occurrence

• Muleros Formation of Chihuahua, Mexico (~ Fort Worth to Denton Limestone horizon)
• Probable Upper Devil's River Formation of south Texas
• Fredericksburg Group, Bee Caves Limestone of Central Texas

Age

• Natica collina Conrad is reported from the lower part of the Washita Group, Late Albian Stage (~100 mya).  Our collecting efforts seem to show a range down into the Fredericksburg Group, ~ Middle Albian Stage (~ 109 mya).  These are very common in the upper Walnut Equivalent

Geographic Occurrence (not an all-inclusive list)

• Chihuahua, Mexico
• Crockett or Val Verde County
• Travis County, Texas

Remarks

         For identification and descriptions, see:

• Conrad, T. A.  1857.  “Descriptions of Cretaceous and Tertiary Fossils”.  In:  Emory, W. H.  Report of the United States and Mexican Boundary Survey, Made Under the Direction of the Secretary of the Interior.  United States 34th Congress, 1st Session, Senate Executive Document 108 and House Executive Document 135 1 (2), 141–174.