†Spironema is a genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of extinct (Cretaceous

Cretaceous

The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...

) sea snail

Sea snail

Sea snail is a common name for those snails that normally live in saltwater, marine gastropod molluscs....

s, marine

Marine (ocean)

Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...

 gastropod mollusks in the family

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 Naticidae

Naticidae

Naticidae, common name the moon snails, is a family of minute to large-sized predatory sea snails, marine gastropod molluscs in the clade Littorinimorpha.Naticidae is the only family in the superfamily Naticoidea....

, the moon snails.

Description

The American paleontologist Fielding Bradford Meek

Fielding Bradford Meek

Fielding Bradford Meek was an American geologist and paleontologist.The son of a lawyer, he was born in Madison, Indiana. In early life he was in business as a merchant, but his leisure hours were devoted to collecting fossils and studying the rocks of the neighborhood of Madison...

 firstly defined this genus in 1864. He classified the genus in the family Littorinidae

Littorinidae

Littorinidae is a taxonomic family of over 200 species of sea snails, marine gastropod molluscs in the clade Littorinimorpha, commonly known as periwinkles and found world-wide.-Names:...

. He recognized two species Spironema bella and Spironema tenuilineata in 1864. These species were previously classified within the family Trochidae

Trochidae

The Trochidae, common name top snails, are a taxonomic family of very small to large sea snails, marine gastropod molluscs in the clade Vetigastropoda ....

. Meek's diagnosis reads as follows:

Species

Species within the genus Spironema include:

• Spironema bella (Conrad) - synonym: Tuba (?) bella Conrad, from Cretaceous of Alabama
• Spironema tenuilineata (Meek & Hayden, 1856) - from Cretaceous of Dakota Territory
  Dakota Territory
  The Territory of Dakota was an organized incorporated territory of the United States that existed from March 2, 1861, until November 2, 1889, when the final extent of the reduced territory was split and admitted to the Union as the states of North and South Dakota.The Dakota Territory consisted of...
  
  , type species: Turbo tenuilineatus Meek & Hayden, 1856 - synonym: Turbo tenuilineata
• Spironema perryi Stephenson - from Maastrichtian
  Maastrichtian
  The Maastrichtian is, in the ICS' geologic timescale, the latest age or upper stage of the Late Cretaceous epoch or Upper Cretaceous series, the Cretaceous period or system, and of the Mesozoic era or erathem. It spanned from 70.6 ± 0.6 Ma to 65.5 ± 0.3 Ma...
  
  , Texas. Spironema cf.
  Cf.
  cf., an abbreviation for the Latin word confer , literally meaning "bring together", is used to refer to other material or ideas which may provide similar or different information or arguments. It is mainly used in scholarly contexts, such as in academic or legal texts...
  
   perryi is also known from the Upper Cretaceous, Cliff House Sandstone, Chaco Canyon, northwestern New Mexico.

Further reading

• Meek F. B. (1876). "A report on the Invertebrate Cretaceous and Tertiary Fossils of the Upper Missouri Country". Report of the United States Geological Survey of the territories, Washington, volume ix: i-ixv, 1-629, plates i-xlv. Spironema is on pages 341-343. Plate 32, figure 9a-c.
• Stephenson L. W. (1941). The larger invertebrate fossils of the Navarro group of Texas. The University of Texas Publication 4101: 1-625.