Annularia

Annularia
Temporal range: Carboniferous
Annularia stellata
Scientific classification
Kingdom: Plantae
Division: Pteridophyta
Class: Equisetopsida
Order: Equisetales
Family: Calamitaceae
Genus: Annularia
Sternberg, 1821

Annularia is a plant fossil belonging to the order Equisetales.

Description

Annularia is a form taxon. It is the name given to Calamites leaves. In fact the stems and the radiating structures of the leaf whorls is similar in the Calamites, an extinct genus of horsetails.

Specimen of Annularia stellata from Italy on display at the Museo Civico di Storia Naturale di Milano

These horsetails, belonging to the class of Sphenopsida, were arborescent and grew to a height of 32 feet (10 meters) in a tree-like form.[1]

Annularia leaves are arranged in whorls of between 8-13 leaves. Its shape is quite variable, being oval in Annularia sphenophylloides and between linear and lanceolate in Annularia radiata, but they are always flat and of varying lengths.[2]

Fossil records

Fossils of this genus have been discovered in the Permian strata of Russia and in the Carboniferous (around 360 to 300 million years ago) strata of the United States, Canada, China and Europe.[2][3]

The foliage of Calamites

See also

References

  1. ↑ Illinois State Museum - Annularia sp. Mazon Creek Fossils
  2. 1 2 MSN
  3. ↑ Paleobiology Database
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