Psaronius
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Psaronius Temporal range: Late Carboniferous–Permian |
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| A transverse section through a Psaronius stem. ~12cm across. | |
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| An equivalent section through a modern tree fern. ~6cm across. | |
| Scientific classification | |
| Kingdom: | Plantae |
| Division: | Pteridophyta |
| Class: | Marattiopsida |
| Order: | Marattiales |
| Family: | Psaroniaceae |
| Genus: | Psaronius |
Psaronius was a Marattialean tree fern which grew to 10m in height, and is associated with leaves of the organ genus Pecopteris and other extinct tree ferns. Originally, Psaronius was a name for the petrified stems, but today the genus is used for the entire tree fern. Psaronius tree fern fossils are found from the Carboniferous through the Permian.
The word Psaronius comes from the Greek ψαρονιος (psaronius, precious stone) the root of which is ψαρον (psaron, a starling bird.] The stone was used for ornamental purposes in Europe and acquired the name for its resemblance to the speckled pattern of the starling. In Germany, the stone was called staarstein. And in English, it was called either starry-stone or starling stone.
Like many extinct trees, psaronius is known by various individual fossil parts that are not always found together. The main parts include: the root mantle, the stem, the fronds, the coziers (fiddleheads), and leaves with spores.
An unusual feature is that Psaronius did not have a true trunk, but had a massive root mantle formed by hundreds of rootlets. These rootlets are referred to as adventitious because they are appearing in an atypical location. These adventitious roots originate in a central stem high in the tree. This central stem becomes smaller lower in the tree so that at the base the mantle is composed entirely of roots. In some specimens, this mantle is over 1.0 m in diameter at the base of the tree. The fossilized wood of this root mantle is simply referred to as Psaronius. The side impressions of these adventitious roots are referred to as Tubiculites by the French Geologist François Cyrille Grand'Eury in 1877.
Like modern tree ferns, Psaronius included other plant species growing in the root mantle. It has been determined through cross-sections of petrified Psaronius, that various vining and epiphytic plants were growing within the tree fern. Some Carboniferous plant species are only known from their fossilized remains within these root mantles. Some of these that have been studied extensively are the epiphyte Botryopteris, the vining climber Ankyropteris and the small climbing ferns called Tubicaulis.
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Wikipedia