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Smithsonian National Museum of Natural History

Big Cedar Ridge, Wyoming: a 73 million-year-old preserved landscape



Fern Wetland

Fossil sites at the south end of the Big Cedar Ridge are dominated by ferns. Several types are especially common, including Hausmannia sp. (F11 - Dipteridaceae), several species of the fern family Gleicheniaceae (F8, F9, F10), and one fern in the family Matoniaceae (F17). Most of these ferns are restricted to the tropics and subtropics today. Soils at the south end of the outcrop are very high in organic matter, even forming a 10 cm thick coal in some places. Few flowering plants grew on this peaty soil, but one that was moderately common was a relative of living buttercups (DN9 - Ranunculaceae).

Reconstruction of the fern wetland vegetation at Big Cedar Ridge, showing cordate leaves of Hausmannia sp., blue-green pinnate leaves of the cycad Ctenis sp., and a specimen of F17 (Matoniaceae). (Mary Parrish reconstruction)

Fossils used in the reconstruction:

The fern Hausmannia sp. (Dipteridaceae).

The fern F8 (Gleicheniaceae).

The fern F9 (Gleicheniaceae).

The fern F17 (Matoniaceae).

The cycad Ctenis sp.

The eudicot DN9 (Ranunculaceae).


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