Pennsylvanian Period Strip Mine Hunt

[Archimedes]

Today we were allowed into a Pennsylvanian Period Strip Mine in NW Alabama to collect and had a wonderful day, a little hot, but nice to be out finding many nice fossils. I forgot my straw hat today so my ears are a little red now. There were many high piles of tailings to search and we found many of the typical Pennsylvanian plant flora, Calamites, Lepidodendron, Stigmaria, ferns, and one interesting type of fern with thorns??? on the stem. We saw many of these in an area with many many layers of them some 14-16 inches thick in the blocks.

The Strip Mine

Calamites below

Pyrite replacement

Stigmaria below

Fern with Thorns??? on stem

Look close at the thorns on the top and bottom.

[AgrilusHunter]

Cool trip and great fossils!

[CH4ShotCaller]

Nice shot of the dig site and finds! Thanks!

[Missourian]

Those are outstanding.

[glacialerratic]

Beautiful stuff!

Were you with a club or was the public allowed in?

[Rockin' Ric]

Nice specimens Archimedes!

[Archimedes]

Thank Youall for your comments

I was also lookig for some comments on the thorns on the fern stem, which I had not seen or noticed before.

[Auspex]

...I was also lookig for some comments on the thorns on the fern stem, which I had not seen or noticed before.

I've seen these interesting structures pictured before, but haven't been able to remember where.

Thorns are an evolutionary adaptation to protect against browsing; since there were no large terrestrial browsers in the Pennsylvanian, I tend to doubt that the structures we see in your specimen are actually thorns.

[RomanK]

Very nice finds Archimedes! I especially like your Pecopteris frond with fern multibranching. As for thorns ... That is unusual and may be have not biological origin. Regards, Roman.

[BNN]

This is really nice material. How large are these pieces?

[Terry Dactyll]

Fantastic finds.... Certainly a place you could discover some carb critters to... get back in there....every week

PS... I havnt seen the thorns on a stem before... Maybe they are old branch nodes perhaps....

Edited September 18, 2012 by Terry Dactyll

[RomanK]

PS... I havnt seen the thorns on a stem before... Maybe they are old branch nodes perhaps....

I think that "thorns" are the transformed prominences on the bark surface of fern branch.

[trilobiteruss]

Good finds, some excellent plants there. Thanks for sharing, having worked in coal geology for 34 years before I retired it is always nice to see some good plant fossils. I used to collect along with everything but now needed to downsize and havve mostly trilobites and a few other invertebrates and a small amount of ferns from concretions and such that I show with the few showy minerals I have :-)

Awesome finds sounds like a great day!

russ

[squalicorax]

Hey Man Really nice stuff. That Calamites Is one of the best ive ever seen.!

[Fossildude19]

I agree with everyone - fantastic finds.

I wonder if you were to try to remove some matrix from around the "thorns" if there would be more exposed?

Could just be, as Roman suggested, protuberances of bark, rather than actual thorns, but,... they are interesting.

Regards,

[Archimedes]

This is really nice material. How large are these pieces?

Thanks for asking

The fern fronds are small and fine, smaller that i normally see

[Archimedes]

Fantastic finds.... Certainly a place you could discover some carb critters to... get back in there....every week

PS... I havnt seen the thorns on a stem before... Maybe they are old branch nodes perhaps....

Thanks, i am looking for insects and wings too, it would really make my day to find a little critter too

[Archimedes]

I think that "thorns" are the transformed prominences on the bark surface of fern branch.

PS... I havnt seen the thorns on a stem before... Maybe they are old branch nodes perhaps....

Thank Youall for your comments

Yes at first I thought this too Roman and Terry but as I look at all the fossils I notice even the very fine stems are covered with these apparent thorns or spines, the fern fronds are small and fine. I have very little experience with plant fossils but have not see fern stems like this before, I normally see smooth uniform stems not this type of spiny looking stems.

Whatever they are it is interesting like Fossildude19 says

Look close at the stem segments they are not smooth but apparently spiny.

Larger stem segment

Edited September 18, 2012 by Archimedes

[Archimedes]

Good finds, some excellent plants there. Thanks for sharing, having worked in coal geology for 34 years before I retired it is always nice to see some good plant fossils. I used to collect along with everything but now needed to downsize and havve mostly trilobites and a few other invertebrates and a small amount of ferns from concretions and such that I show with the few showy minerals I have :-)

Awesome finds sounds like a great day!

russ

Haha yes I like the downsize idea, i go to earth day and give alot away to the kid interested in fossils

[trilobiteruss]

Haha yes I like the downsize idea, i go to earth day and give alot away to the kid interested in fossils

Haha yes I like the downsize idea, i go to earth day and give alot away to the kid interested in fossils

Yes that is always fun, used to give away dinosaur bone pieces I collected on my digs to kids and other items. Good way to plant some seeds in future paleontolgists!

[AgrilusHunter]

Hi Archimedes, cool fossils! I don't know if these are thorns, at least not in comparison to a thorn on modern plants. I agree with Auspex, thorns are an evolutionary response to browsing by large vertebrate animals. These plants would not have been under that type of pressure. I can offer an alternative guess though. Thorns are thought to have evolved, possibly, from trichomes. Certainly there were very large herbivorous insects during this time period that could have provided evolutionary pressure. If these structures are real, not simply branches, rootlets, senescent fronds, etc., then they could be a defense against insect herbivores. Many trichomes on modern plants are quite small and tipped with sticky substances and chemical deterrents but the insects they are defending against are much smaller too. Perhaps in the Carboniferous both the insects and the plant defenses against those insects were giant!

Edited September 19, 2012 by AgrilusHunter

[RomanK]

Thank Youall for your comments

Yes at first I thought this too Roman and Terry but as I look at all the fossils I notice even the very fine stems are covered with these apparent thorns or spines, the fern fronds are small and fine. I have very little experience with plant fossils but have not see fern stems like this before, I normally see smooth uniform stems not this type of spiny looking stems.

Whatever they are it is interesting like Fossildude19 says

Look close at the stem segments they are not smooth but apparently spiny.

Larger stem segment

I was really expressed by "thorns"!! That is very interesting!

[mzkleen]

Great finds!! They remind me of the St. Clair ferns.

[Archimedes]

Hi Archimedes, cool fossils! I don't know if these are thorns, at least not in comparison to a thorn on modern plants. I agree with Auspex, thorns are an evolutionary response to browsing by large vertebrate animals. These plants would not have been under that type of pressure. I can offer an alternative guess though. Thorns are thought to have evolved, possibly, from trichomes. Certainly there were very large herbivorous insects during this time period that could have provided evolutionary pressure. If these structures are real, not simply branches, rootlets, senescent fronds, etc., then they could be a defense against insect herbivores. Many trichomes on modern plants are quite small and tipped with sticky substances and chemical deterrents but the insects they are defending against are much smaller too. Perhaps in the Carboniferous both the insects and the plant defenses against those insects were giant!

I have gotten several emails from several biologists and they too think they are trichomes but they go on to say that trichomes can also be adaptations to other functions such as dessication resistance

another thought they were used to hang onto other plant to aid and get their foliage above the other plant

[AgrilusHunter]

I have gotten several emails from several biologists and they too think they are trichomes but they go on to say that trichomes can also be adaptations to other functions such as dessication resistance

another thought they were used to hang onto other plant to aid and get their foliage above the other plant

All sound plausible. I'm not as convinced about the anti-dessication hypothesis. Certainly, modern dicots use trichomes to this effect, but considering these fossil were laid down in a rainforest like environment I'm not sure there would have been evolutionary pressure towards this trait. Also, in modern plants with this trait the trichomes are small and dense to protect against solar radiation and wind dessication. The structures on your specimens are "spine-like", to me they look analogous to modern thorns, as you first suggested. Considering the size of the arthropod herbivores during the Carboniferous (think Arthropleura) I see no reason why the plants would not have evolved a mechanical defense against them.

Edited September 20, 2012 by AgrilusHunter