A Strange Rhode Island Fern

[Philosoraptor]

I was going through some material from Cory’s Lane, a Carboniferous fossil site in Rhode Island, when I noticed this fern. It didn’t really look like anything else I had and so I came here for some help. I’m very new to identifying fern fossils, so any help is greatly appreciated. 

 

[Tidgy's Dad]

Alethopteris I think. 

You have some of the parallel blades running away from the missing main rachis (stem).

 

[piranha]

Pecopteris arborescens

 

figures from:

 

Lyons, P.C., & Darrah, W.C. 1978

A late Middle Pennsylvanian flora of the Narragansett basin, Massachusetts.

Geological Society of America Bulletin, 89(3):433-438

 

[doushantuo]

Didn''t Bguild have a post on this flora? 

[piranha]

Additional research shows Wagner & Lyons 1997 subsequently reclassified Pecopteris arborescens as Pecopteris cf. nyranensis.  Recently, there seems to have been some back and forth taxonomic confusion about "Pecopteris" in the last few years.  Hopefully, JackW @fiddlehead can clarify the current taxonomy of this particular species.

 

Wagner, R.H., & Lyons, P.C. 1997

A critical analysis of the higher Pennsylvanian megafloras of the Appalachian region.

Review of Palaeobotany and Palynology, 95:255-283

[Rockwood]

If all else fails the powder from them (graphite) makes a great lock lubricant. 

[Plantguy]

Graphite!?...dont talk about graphite. LOL...you kidding me?....LOL! Yes!!!

 

Bguild did! 

 

Yep, That is another nice example. Looks like Scott has already provided the Pecopteris ID and a great reference. He's the best. 

 

I am still curious about how fine the preservation is...By any chance can you see any leaf veins in any part of the specimen and how the "leaves" are attached to the "stem"? They appear to be attached at their bases as in the Pecopteris photo/sketch below..

Here are some good comparative veination pattern photo/sketches from some of the common plant forms. They are found in: 

Concise Guide to Common Plant Fossils of West Virginia

Images from: Plant Fossils of West Virginia (WVGES ED-3A; Gillespie, Clendening, and Pfefferkorn, 1978) Illustrations by: B. Schleger

You can download the entire pdf from the West Virginia geological survey @

http://www.wvgs.wvnet.edu/www/geoeduc/AdaptiveEarthScienceActivities/Extras/ConciseGuideToPlantFossilsWV.pdf

 

Regards, Chris 

[doushantuo]

Nobody asked @paleoflor anything yet....

[Rockwood]

 

6 minutes ago, Plantguy said:

Graphite!?...dont talk about graphite. LOL...you kidding me?....LOL! Yes!!!

One should check to make sure he is a bachelor before splitting these on the kitchen floor.  

[doushantuo]

[Fossildude19]

2 minutes ago, doushantuo said:

Just wondering how this applies to the conversation? 

[doushantuo]

my bad,Tim

 

 

[Fossildude19]

6 minutes ago, doushantuo said:

my bad,Tim

Ah - that makes sense. 

Thanks, Ben.  

[doushantuo]

Although W & L (1997) do not (seem to) offer support for their systematic vision.

Because both names figure rather largely in Carboniferous paleobotany ,I tend NOT to doubt their view.

edit: At least one Pecopteris species might be the fertile axes of Asterotheca, I think

Pecopteris vestita (congeneric with syntypes of Filicites miltoni) might be Lobatopteris, but Fiddlehead or Tim might have their say in this

Anyway:NICE finds, Philo!!

[fiddlehead]

  Taxonomy is based on the original authors description, figures and type specimens. Anything after that is is the opinion of the author citing that name. It most be pointed out when mistakes are made, there are peer reviewed revisions written for the original diagnosis. In this case the name stays the same, but the revising author would need to be cited with that taxon name. This specimen, in my opinion, based on seeing many examples of specimens which conform to the original description by Schlotheim (and later see below). The following is my interpretation of this taxon. The ultimate pinnae are straight, and of an equal width for their entire length, and terminate in a blunt lobe. The rachis is straight and heavy. The pinnules are alternate, closely placed, about twice as long as broad, about 5 mm or less in length, straight-sided, nearly rectangular in appearance and free all the way to the pinna tip. They arise at a right angle or very slightly oblique to the rachis. And have simple venation. You will noticed I have not said the name The reason is for nearly 200 years this fossil form had the name arborescens, given by Schlotheim. It has since been ruled by the ICBN (Art. 13.1f) that all of Schlotheim’s names predate the cutoff period for valid taxonomic names and have no validity. The reason for this is Schlotheim did not erect type specimens and his descriptions were poorly written, verging on fanciful. The first validly erected name for this species is now arborea. It was erected by Sternberg, apparently not recognizing the form had been described by Schlotheim two years earlier.

  The genus of Pecopteris is easily the biggest nomenclature problem in Palaeozoic paleobotany. It was a name erected by Brongniart to be used for fossil plants with pinnated leaves. This included members of seed ferns, like Alethopteris and Mariopteris. As these genera were better understood they were removed and Pecopteris was left to only represent true ferns. But the type species for Pecopteris is Senftenbergia plumosa which has unique fertile structures and is not a member of the order Marattiales. The problem now is Marattiales contains nearly all the species of Pecopteris making all of them a nomenclature problem. Today Pecopteris remains as a matter of convenience for less understood fern species, or species with a combination of features which do not easily fit into a better defined genus. That said, today fossil ferns with the fertile structures and vein architecture seen with arborescens/arborea are placed in the better defined genus Cyathocarpus. Short version, in my opinion it a Cyathocarpus arborea (Sternberg) Mosbrugger, 1983.

 

FYI, In the Wagner, 1997 publication in his opinion the specimens found in a particular locality were not "Pecopteris arborescens" and he was not commenting on the name per se. 

 

 

[piranha]

7 minutes ago, fiddlehead said:

  Taxonomy is based on the original authors description, figures and type specimens. Anything after that is is the opinion of the author citing that name. It most be pointed out when mistakes are made, there are peer reviewed revisions written for the original diagnosis. In this case the name stays the same, but the revising author would need to be cited with that taxon name. This specimen, in my opinion, based on seeing many examples of specimens which conform to the original description by Schlotheim (and later see below). The following is my interpretation of this taxon. The ultimate pinnae are straight, and of an equal width for their entire length, and terminate in a blunt lobe. The rachis is straight and heavy. The pinnules are alternate, closely placed, about twice as long as broad, about 5 mm or less in length, straight-sided, nearly rectangular in appearance and free all the way to the pinna tip. They arise at a right angle or very slightly oblique to the rachis. And have simple venation. You will noticed I have not said the name The reason is for nearly 200 years this fossil form had the name arborescens, given by Schlotheim. It has since been ruled by the ICBN (Art. 13.1f) that all of Schlotheim’s names predate the cutoff period for valid taxonomic names and have no validity. The reason for this is Schlotheim did not erect type specimens and his descriptions were poorly written, verging on fanciful. The first validly erected name for this species is now arborea. It was erected by Sternberg, apparently not recognizing the form had been described by Schlotheim two years earlier.

 

  The genus of Pecopteris is easily the biggest nomenclature problem in Palaeozoic paleobotany. It was a name erected by Brongniart to be used for fossil plants with pinnated leaves. This included members of seed ferns, like Alethopteris and Mariopteris. As these genera were better understood they were removed and Pecopteris was left to only represent true ferns. But the type species for Pecopteris is Senftenbergia plumosa which has unique fertile structures and is not a member of the order Marattiales. The problem now is Marattiales contains nearly all the species of Pecopteris making all of them a nomenclature problem. Today Pecopteris remains as a matter of convenience for less understood fern species, or species with a combination of features which do not easily fit into a better defined genus. That said, today fossil ferns with the fertile structures and vein architecture seen with arborescens/arborea are placed in the better defined genus Cyathocarpus. Short version, in my opinion it a Cyathocarpus arborea (Sternberg) Mosbrugger, 1983.

 

FYI, In the Wagner, 1997 publication in his opinion the specimens found in a particular locality were not "Pecopteris arborescens" and he was not commenting on the name per se.  

 

 

Thanks for this thorough explanation, Jack.  Very much appreciated! 

[Plantguy]

8 minutes ago, piranha said:

 

 

Thanks for this thorough explanation, Jack.  Very much appreciated! 

ditto! 

Regards, Chris 

[doushantuo]

Totally agree with the others,and the background info about Schlotheim is VERY much appreciated.

a bit of phytogeography:

 

From:

"reply of the month?"