Mazon Creek Flora

[connorp]

Here's another nice association. The fern pinna is probably Pecopteris oreopteridia. On the left is a small fragment of Sphenophyllum emarginatum. The item above it might be a small seed of some sort, I'm not sure though.

 

 

[Mark Kmiecik]

Nice combo!

[Wrangellian]

Good thread.,.. I like the Paleozoic plants and the Mazon seems prominent in that area, though I don't know much about them.

[connorp]

This concretion opened over the weekend, I was quite happy. It is a piece of Diaphorodendron rimosum lycopsid bark. It is rare in the Mazon Creek flora, although more common in similarly aged strata elsewhere in Illinois.

 

 

[deutscheben]

That’s a lovely little snippet of bark!

[connorp]

I've had a couple exciting finds over the past couple weeks. The first is Cordaianthus ovatus, the fertile structure of Cordaites. This is the first I've found, and a sizeable example at that.

 

 

 

Second is what I believe to be Rhacophyllum molle, which is a possible aquatic plant.

 

[Mark Kmiecik]

Sweet! And you're sure it's not a shark tooth? 

[connorp]

Here's a cute little Annularia radiata. Pretty common, but I still love finding them.

 

[connorp]

Here's another little Annularia radiata.

 

[connorp]

A very partial Lepidostrobus triangulare lycopsid cone

[Mark Kmiecik]

Very nice cone. 

[connorp]

 

A new cone bract species for me - Lepidostrobophyllum ovatifolius.

[connorp]

 

Here's something a bit different. This is the pollen organ Codonotheca caduca, which may have been borne on the same plant as Macroneuropteris. Had my first specimen of this species open Saturday, and a second one Sunday. Love when that happens

[connorp]

 

Here's a really beautiful example of Pecopteris fontainei. Interestingly, despite the generic name, this is believed to be a seed fern.

[Mark Kmiecik]

That's a keeper.

[connorp]

Here's a well preserved example of a Macroneuropteris scheuchzerii orbicular pinnule. These small pinnules are attached in pairs at the base of the more elongated pinnules.

 

[connorp]

Here's a nice example of Annularia sphenophylloides. In regards to this species, Lesquereux said "the plants present a very beautiful appearance, resembling small open roses flattened upon the stone."

 

[connorp]

Here's a colorful Diplazites unita, which was snapped in half just prior to fossilization.

 

[connorp]

This is one of the best Macroneuropteris scheuchzerii pinnules in my collection, but it is actually not from Mazon Creek. This concretion was collected from roof shales of the Herrin Coal in eastern Illinois. Still in the Carbondale Formation, but a bit younger than the Mazon Creek flora.

 

[deutscheben]

That's an outstanding one! I'm in awe of people finding nice plants in the concretions from there, I haven't been able to crack any yet.

[connorp]

On 7/14/2022 at 11:12 AM, deutscheben said:

That's an outstanding one! I'm in awe of people finding nice plants in the concretions from there, I haven't been able to crack any yet.

They don't seem to be very plentiful. I've found mostly plant scrap jumbles or Dunbarella fragments in the concretions.

[connorp]

Here is one of the better specimens of Crenulopteris subcrenulata I've found. These is an interesting species that shows a lot of variation depending where on the frond it was located.

 

[connorp]

Finding the Crenulopteris subcrenulata I posted above motivated me to look back at others I had labeled as such. This fern was collected last year and I had labeled it as C. subcrenulata, but I now believe it is the rarer Pecopteris serpillifolia, a new species for me.

 

 

Here is a close up of some of the better preserved pinnules. Most of the pinnules on this specimen are covered with scales, a feature of P. serpillifolia, C. subcrenulata, and a couple other Mazon Creek pecopterids.

 

The lateral veins are hard to make out in the scale-covered pinnules, but there are a few where the venation is very clear. The venation fits P. serpillifolia well - distant, simple, and straight lateral veins, and a decurrent midvein that forks near the pinnule apex.

 

Edited July 19, 2022 by connorp

[connorp]

To continue with interesting pecopterids, I believe this next specimen to be Pecopteris strongii.

 

 

This form was described by Lesquereux under Pecopteris resupinata, but is instead represents an immature P. strongii. Here is the entry from A Dictionary of the Fossils of Pennsylvania and Neighboring States (1889).

 

[connorp]

Here's a small but well preserved Calamostachys tuberculata, a cone of Calamites.