SDNHM catlalog no. 25925. Apporahid snail fossil in matrix. This specimen measures approximately 4.5 inches (11.6 cm) in length.

Anchura gibbera
Apporahid snail
Strombacea

Time
Cretaceous Period

In Our Region
Shells of A. gibbera have been collected from Cretaceous-age siltstones in Carlsbad, CA, USA, and in Santa Catarina, Mexico.

Description
Anchura gibbera is an extinct species of winged apporahid snail. The shell whorls were rounded and marked with serrated ridges. The base of the shell, the last and largest whorl, had a prominent outer lip—the "wing," which flared away from the shell, and ended in a point. The siphonal canal, which was used for water intake, was long and thin.

The wing may have protected the snail's body, particularly the head, as it fed along the sea floor.

Because fossil shells of this extinct snail are both distinctive and found only in Cretaceous-age marine deposits, it is considered an index fossil.

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