Progymnosperms

PALAEOBOTANICAL RESEARCH GROUP

UNIVERSITY MÜNSTER

HISTORY OF PALAEOZOIC FORESTS
THE EARLY FORESTS AND THE PROGYMNOSPERMS

The first trees appeared in the Middle - Late Devonian. One of the oldest fossil forests was found in the famous Gilboa locality (Givetian). The Late Devonian Archaeopteris has fronds with fan-shaped leaflets and is a well-known example of an early tree. This latter form belongs to the group of the Progymnosperms. The silicified wood of Archaeopteris is known as Callixylon. Callixylontrunks may reach a considerable diameter.

Taxon / Subject	Web Source	Comments	Pics	Info
Gilboa Forest	Prof. Robert Titus, Hartwick College
Progymnosperms	Univ. California Mus. Paleontology, Berkeley
*Tetraxylopteris*
Tetraxylopteris schmidtii	Virtual Paleobotany Laboratory
The genus Archaeopteris was originally established for Devonian foliage with fan-shaped pinnules. *Archaeopteris* is very widespread and has been reported from North and South America, Europe and Aisa; several localities have yielded very large frond portions, e.g., Bear Island (Arctic), Kiltorckan (Ireland). The leaves bear macro- and microsporangia which are roughly of the same size and shape. The foliage has been correlated with the petrified wood *Callixylon* and the name Archaeopteris is also used for the reconstructed plant.
Archaeopteris	Univ. California Mus. Paleontology, Berkeley
Archaeopteris	Kathleen Pigg's "Plant Fossils and Evolution"	Sterile and fertile leaves
Archaeopteris	Paleontologisk Museum, Oslo
Archaeopteris	Media del Gekko
Archaeopteris	ABC News - Science	Same pictures as above
Archaeopteris	Botanik-online
Archaeopteris	The Forestry Source	News item - mainly text
Archaeopteris gaspensis	Virtual Paleobotany Laboratory
Archaeopteris halliana	Senckenberg, Frankfurt am Main	Illustration on a stamp !
Archaeopteris halliana	Parcs Canada
Archaeopteris hibernica	The Cork Geology Museum (Ireland)
Archaeopteris hibernica	Palaeobotany, Royal Holloway University London
*Callixylon* is the wood of the *Archaeopteris* tree
Callixylon	Virtual Paleobotany Laboratory	radial section
Callixylon	Virtual Paleobotany Laboratory	tangential section
Callixylon	Virtual Paleobotany Laboratory	permineralized trunk
Callixylon	Plant fossils of Kentucky, KGS
Callixylon	East Central University, Ada, OK
Callixylon	Univ. California Mus. Paleontology, Berkeley	same picture as above, in reverse!

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Disclaimer

The last check of the list of links was done on 25 November 2002. The links give the most direct connections to pictures available on the web; in many cases they are from sites that have additional palaeobotanical information. The above ratings refer to:
1. Pics: the quality of the specimens, particularly with regard to characteristic features, and to the quality of the pictures.
2. Info: the additional information provided; if applicable te general information on the main pages has been considered.
Ratings are of course subjective but should be helpful for finding the fastest way to good pictures on the web. Own pictures are of course not rated. This is up to you!
Although links are checked regularly, some may be outdated. Suggestions for improvement and hints to other internet resources are most welcome

November 2002