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Psilophyton is a genus of extinct vascular plants. Described in 1859, it was one of the first fossil plants to be found which was of Devonian age (about 420 to 360 million years ago ). Specimens have been found in northern Maine , USA; Gaspé Bay , Quebec and New Brunswick , Canada; the Czech Republic ; and Yunnan , China.
The class was created in 1917 by Kidston and Lang for fossils found in the Rhynie Chert Bed. [4] Three genera were initially included, Rhynia, Horneophyton and Psilophyton. All lacked leaves and true roots, consisting only of branched stems; however they were considered to contain vascular tissue. [1] Additional fossil genera were added later.
Trimerophytopsida (or Trimeropsida) is a class of early vascular plants from the Devonian, informally called trimerophytes.It contains genera such as Psilophyton.This group is probably paraphyletic, and is believed to be the ancestral group from which both the ferns and seed plants evolved.
The first species of this genus (Sawdonia ornata) was described in 1859 by Sir J. William Dawson and, was originally attributed to the genus Psilophyton. He named this plant Psilophyton princeps. In 1971 Francis Hueber proposed a new genus for this species due to its "Divergent technical characters from the generic description for Psilophyton."
Psilotum is a genus of fern-like vascular plants.It is one of two genera in the family Psilotaceae commonly known as whisk ferns, the other being Tmesipteris.Plants in these two genera were once thought to be descended from the earliest surviving vascular plants, but more recent phylogenies place them as basal ferns, as a sister group to Ophioglossales.
The identification of plant fossils in Cambrian strata is an uncertain area in the evolutionary history of plants because of the small and soft-bodied nature of these plants. It is also difficult in a fossil of this age to distinguish among various similar appearing groups with simple branching patterns, and not all of these groups are plants.
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The Museum of the Rockies is a Smithsonian affiliate museum, and had long promised to find a T. rex for the Smithsonian to display. [75] Due to the 2013 federal government shutdown, the fossil did not arrive in Washington, D.C. Smithsonian officials said it remained in storage in Montana, and would not arrive at the Smithsonian until late ...