Rugosa Coral

[gobbler716]

I have been told that this is a piece of rugosa coral. It was found about 5 miles from the Tennessee River, near Scottsboro, Alabama. What do you think?

It was found on a gravel road with similar colored rocks, etc. about 50 years ago.

Age?

Era?

[Auspex]

I agree that a rugose horn coral is involved; whether it is a partial, or a mold of the top, is not clear to me in this angle. A shot of the small end might settle that.

Looks a little like Devil's Tower, no?

[gobbler716]

Yes, I always thought it looked like Devils tower....

[Rockwood]

I'd place the odds on mold.

[gobbler716]

Thanks.

[FossilDAWG]

It's a mold of the calyx of a solitary coral. We would need to see an end-on view to narrow the ID further, but even then it would be very difficult even to get to genus. As it is, we can't be sure even that it is rugosan, though that might be most likely given the area it was collected, assuming the gravel had a local origin. However solitary scleractinian corals can look just like that as well, you would have to look at the pattern of septa to confirm rugosan or scleractinian.

Don

[gobbler716]

Yes about the road material. At the time the drive to the cemetery was used, then washed out. So, the sample here was a natural part of the driveway. I appreciate all of the comments.

[Pumpkinhead]

Count the septa like fossildawg said, if it is rugosa the septa will be a multiple of four. If not its something else

[janislav]

The only way I have been able to count septae is to make a microscopic slide of a slice across the coral top - a process requiring some fairly specialized equipment and lots of time polishing the thin section. Rugose corals were present during the paleozoic while scleractinian corals first appeared in Triassic times. Gravel is rarely hauled more than a few miles from the quarry for road building, so if the bedrock in the area is paleozoic, the coral is almost certainly a rugose coral.

Edited June 10, 2015 by janislav