Jump to content

colonial rugose coral or heliolitid or ???


LisaL

Recommended Posts

Hi, everyone,

 

(Just a note that this isn't my specimen or photos -- it was posted earlier today on the Fossil Forum facebook group, and my curiosity over what it is has been bothering me all day. The OP found it along the shore of Delaware Bay years ago, he thinks. Not sure whether he was on the Delaware or NJ side)

 

My guess is that it's a colonial rugose coral like Palaeophyllum, mainly because the longitudinal corallite cross sections in the second photo don't look like heliolitid corallites all packed together, bigger and smaller.

 

But if it is a rugose coral colony, I wondered whether phaceloid colonial rugose corallites can have coenenchymal tissue among them, or if this is something reserved for helolitids. When this photo is enlarged, it looks like there's coral microstructure in the matrix between and inside the corallites. Is it just typical to see this kind of texture in the matrix of rugose colonies?

 

Many thanks-- I hope the question makes a bit of sense!

Lisa

image.thumb.jpeg.872cf3a4afcb4ef23242b282720adffe.jpegimage.thumb.jpeg.1ff40d72a21963b8f6399958b26f34b1.jpegimage.thumb.png.4490fe56345cb55be414924ecb20c4ae.png

Link to comment
Share on other sites

Hi Lisa! 

 

I'm pretty sure it's a phaceloid rugose colony. The photos aren't clear enough to see what's really going on but there are a couple of possibilities I can think of.

First, corallites can rejoin for a while in some phaceloid colonies, as in the Carboniferous Siphonodendron in my photos - not a coenenchymal structure though. It's really an intermediate form between cerioid and phaceloid and its extent varies a lot. The corallites sometimes merge at specific horizontal levels and then re-separate.

Second, maybe an encrusting bryozoan?

I prefer the first from what I can see, the extra coral tissue being dissepimental.

 

IMG_1717.thumb.jpeg.b454414097d3c5c5a856da5e0116971c.jpeg

 

5d5bb8037be51_IMG_17152.thumb.jpeg.7e9fcf0b91742363252da112ad4c6dd0.jpeg

IMG_1708.thumb.jpeg.b6d180dde718659fb8aa87c170ae33ab.jpeg

  • I found this Informative 6

Tarquin

Link to comment
Share on other sites

Thank you so much for taking the time to teach and share, Tarquin! These photos are incredible -- I love seeing the dissepiments on either side of the tabulae magically twine together like rope, then diverge. I finally see that the specimen I posted is so eroded and worn that it's impossible to discern a species or even genus. I was trying to match the shape of the septa to illustrations in the Treatise and hit on Paleaophyllum, but it could just as well be any phaceloid rugose colony known from the Devonian or Silurian (which I *think* is what most of the rocks are in the OP's area.) Anyway, the exact diagnosis isn't important; I'm excited to make any small progress in interpreting the details I'm seeing! And thank you for clearing up that the texture I was confusing for coenenchyme is most likely dissepimental material. I probably should've been able to figure that out. :P 

 

(Btw, after posting this last night, I searched the forum for examples of phaceloid corals and ran across your thread on Carboniferous Corals of the UK. Wow! It's been hard to pry myself away!)  :) 

Link to comment
Share on other sites

@LisaL It's a pleasure to share with another coral fan and I'm glad you like my thread. It helps to make it worthwhile! :)

 

Thank you for your very kind comments. :)

Tarquin

Link to comment
Share on other sites

I'm sure you've heard this before, but it would be exciting to see your photos and descriptions published as a monograph! In the meantime, I feel super lucky to be able to explore them here.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...