A petrified mini-ecosystem: fern rhizome in nurse log

[paleoflor]

L.S.,

 

Wanted to share this "mini ecosystem" in fossilized form. The photos below show a rhizome of Osmunda pluma Miller 1967, a member of the royal fern family, from the Paleogene of the Fort Union Group (probably the Sentinel Butte Fm.) near Glenn Ullin in Morton County, North Dakota. On the first photo you can see a central stele surrounded by "eyes", which are cross-sections through the petioles of the leaves of the fern (see for comparison this section made through an extant Osmunda cinnamomea rhizome). More to the top and bottom of the photo, parallel lines are visible. These are the remnants of a woody texture, probably of some kind of gymnosperm (see also the second image, a flatbed scan of the entire slab containing the fern rhizome). According to Miller (1967, p. 143) the fern was growing on a so-called "nurse log": when a tree in the woods falls over and starts to decay, this can provide an excellent opportunity for new plants to grow! See for example these lovely examples of modern nurse logs.

 

Cheers,

 

Tim

 

Fern rhizome of Osmunda pluma Miller 1967 showing central stele and petioles

 

The fern rhizome is embedded in a woody texture, interpreted as a nurse log.

 

[Tidgy's Dad]

Very interesting and rather pretty.

[Fossildude19]

Very cool fossil, Tim.

Thanks for sharing it here.