The Paleontology of North America

Horsetails and Relatives from North America

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Annularia
Annularia
© 1995 UCMP

Calamites
Calamites
© 2004 UCMP

Calamites
Calamites
© 2003 Thomas Kammer

What are Horsetails and Relatives? The horsetail rushes and their relatives form the group Sphenophyta. They are represented today by only one genus, Equisetum, also called the scouring rush. Fossil and modern horsetails are easily recognized by the whorls of leaves or branches at the nodes of their jointed stems. They also have reproductive organs loosely arranged in cone-like structures called strobili. They were very abundant and diverse through the Late Paleozoic, and some Carboniferous horsetails grew to heights of 10 meters.

First known fossil occurrence: Devonian.

Last known fossil occurrence: Quaternary. This group has living relatives.

Fossils through time:
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Quaternary
Tertiary
Cretaceous
Jurassic
Triassic
Permian
Carboniferous
Devonian
Silurian
Ordovician
Cambrian
Precambrian