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Eocene Crinoids From North Carolina


Al Dente

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I have been searching the Castle Hayne Formation (Mid to Late Eocene) for crinoids for many years. Here are a few that I wanted to share. All but one species of crinoid in the Castle Hayne Formation are comatulid crinoids. Comatulids are stalkless and are better known today as "feather stars". Here is a picture of a modern comatulid from Wikipedia-

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Here is a view of a dried comatulid showing the underside - referred to as the dorsal side even though in life it faces downward-

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In the center of this dried specimen is an ossicle known as the centrodorsal. There are cirri that grow out of the centrodorsal that act as legs and there are 5 plates known as radials that are attached to the centrodorsals in living comatulids that are frequently still attached on the fossil comatulids. Circular scars are found on the centrdorsals where cirri were once attached. These scars can be important for identification.

The first Castle Hayne comatulid was identified by Ebenezer Emmons in 1858. He named it Microcrinus conoideus. Here is his drawing and one of my examples.

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Microcrinus are easy to identify. They have 5 paired columns of cirri scars with smooth areas in between. No other comatulids in the Castle Hayne have this feature. My example has 4 of the 5 radials present. Emmons' drawing is missing the radials and you can see 5 partitions inside. This is typical for Microcrinus. Here are two more. The one on the left is missing the radials and you can see the 5 partitions inside.

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Here is an unidentified comatulid that has similar partitions as Microcrinus but is much larger, more bowl shaped and instead of the 5 paired columns of cirri scars, this is completely covered with cirri scars.

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A paper published in 2004 by Ciampaglio and Weaver identifies comatulid crinoids from the Castle Hayne Formation. They listed seven species from seven genera. I've tried to match my fossils with theirs and have a few that are pretty good matches (including Microcrinus already shown above). The first is Amphorometra parva. A. parva have 10 columns of vertically stacked cirri scars and a nice star pattern on top-

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The second is Placometra veniti. It also has the vertically stacked columns of cirri scars but has a truncated dorsal side (bottom of cup) and 5 prominent ridges located between the pairs of stacked cirri scars-

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The Ciampaglio and Weaver paper has several tiny comatulids that I can match to some of my specimens but I think there is a possibility that some might be variations of the same species. Studies on modern comatulids have shown a lot of variation in the centrodorsals within a single species. This includes shape and number of cirri scars present. There is a paper on the Cretaceous comatulids from Texas by Peck and Watkins that demonstrates changes in the centrodorsals with size within a species. Here's a picture from their paper demonstrating this variability-

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Here is one of my specimens that looks very much like Hertha plana from the Ciampaglio and Weaver paper-

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H. plana is one of the comatulids that I think may be a small stage of the common Himerometra bassleri. Here is what the larger ones look like. The first example lacks the 5 radials and the second has the 5 radials.

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Here is a group of comatulids that may be different species but I suspect they are all H. bassleri-

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Here is another unidentified comatulid. This one is different in having large alternating cirri scars instead of parallel columns. The first is lacking the radials, the second has them.

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Along with the centrodorsals, I find a lot of pieces of cirri and arms of teh crinoids but they aren't diagnostic. Here are a few pieces-

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Stalked Crinoids-

There is a single species of stalked crinoid in the Castle Hayne Formation. It is Decmocrinus simmsi (Ciampaglio et al. 2007). It is a type of crinoid known as a bourgueticrinid. They are tiny but very common in some Castle Hayne sediment. The crowns are plain-

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The columns are unusual for crinoids. They don't have the typical pentameral symmetry of a lot of crinoids but are more bilaterally symmetrical-

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Here is what a nearly complete bourgueticrinid crown and stem would look like-

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References:

Ciampaglio, C.N., Weaver, P.G., 2004. Comatulid Crinoids from the Castle Hayne Limestone (Eocene), Southeastern North Carolina. Southeastern Geology, 42 (3), 179-187.

Ciampaglio, C.N., Donovan, S.K., Weaver, P.G., 2007. Gracile bourgueticrinids (Crinoidea) from the Castle Hayne Formation (Eocene), Southeastern North Carolina, USA. Swiss Journal of Geosciences, 100: 243-249.

Emmons, E., 1858. Report of the North Carolina Geological Survey, Agriculture of the Eastern Counties; together with Descriptions of the Fossils of the Marl Beds.

Peck, R.E., Watkins, W.T., 1972. Comatulid Crinoids from the Lower Cretaceous of Texas. Journal of Paleontology, v. 46, No. 3, p. 410-414.

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Eric

Really interesting. Looks like most of your specimens would be caught for sure by window screen. You mention that some species are common. Are all the species that you show common in the Castle Hayne Formation? With all the limestone debris, I would imagine that these are difficult to spot in the matrix especially the smaller specimens.

Marco Sr.

"Any day that you can fossil hunt is a great day."

My family fossil website     Some Of My Shark, Ray, Fish And Other Micros     My Extant Shark Jaw Collection

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You mention that some species are common. Are all the species that you show common in the Castle Hayne Formation? With all the limestone debris, I would imagine that these are difficult to spot in the matrix especially the smaller specimens.

Marco Sr.

Marco

One of the Castle Hayne outliers that I used to collect almost completely lacked crinoids but all the other sites have numerous crinoids. Democrinus is the most common with Microcrinus second and Himerometra third. When I sort though Castle Hayne material I go very slowly and look at every grain. Not many shark teeth found this way but a good variety of invertebrates. I use a 1 mm. screen. I've tried smaller but it is too tedious.

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Excellent presentation, Eric. I can appreciate your efforts in the photography of small finds. I occasionally find pieces of the Cretaceous comatulids here in Texas, and your topic has improved my understanding of them.

The human mind has the ability to believe anything is true.  -  JJ

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Very nice thread sir. This will definitely help others with IDs.

Pretty cool little crinoids.

I have yet to get my hands on Castle Hayne matrix.

~Charlie~

"There are those that look at things the way they are, and ask why.....i dream of things that never were, and ask why not?" ~RFK
->Get your Mosasaur print
->How to spot a fake Trilobite
->How to identify a CONCRETION from a DINOSAUR EGG

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Al Dente,

Interesting. I don't think I've seen crinoid specimens from NC before - particularly Eocene ones. I used to see Eocene ones from Oregon at shows.

Jess

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  • 7 months later...

Just read this now Eric. I need to start looking in the member collections section! I received a thorough education from this. Thanks for enlightening us.

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  • 5 weeks later...

Ditto!

"A problem solved is a problem caused"--Karl Pilkington

"I was dead for millions of years before I was born and it never inconvenienced me a bit." -- Mark Twain

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  • 11 months later...

I wanted to give this thread a bump. I search for it every now and then when I come across crinoids from the N.C. Castle Hayne.

Wonder moderators, could we pin this?

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  • 3 months later...

I think I might have some crinoids, so now I have a way to verify! Thanks so much, Al, for this amazing collection of fossils with descriptors, etc... awesome help for laymen!

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  • 1 year later...

Very interesting article. I've been to the Castle Hayne quarry multiple times, but only recently hit upon my liking of the micro world. Wish I would have discovered that area a little sooner. Thanks for the great info, when I make it back there I know one of the items that I will certainly be looking for (besides echinoids of course).

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  • 5 months later...

Absolutely fascinating! The preservation, presentation, and the addition of knowledge is truly praiseworthy. Generations, hopefully, will benefit greatly!

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