???? Mosaic of crystal?? North Sulphur River

[shel67]

I found this at the North Sulphur River today, Ladonia, Texas. I was sifting through the gravel, and this beautiful mosaic appeared in the water. It’s a mosaic of tiny squares and when it is wet the colors are brilliant! Any ideas of what exactly this might be?

[ynot]

Looks like a tabulate coral.

[DPS Ammonite]

It looks like Paleozoic tabulate coral. The fossil is probably replaced by silica (does a steel knife blade scratch it?). I don't recall any silicified fossils at NSR except for petrified wood. If it is a tabulate coral which went extinct in the Permain before the Cretaceous, the fossil has been brought in by ancient rivers, human beings or is from reworked gravels from an unknown formation.

 

Please show us what the other sides look like.

 

[Ludwigia]

Do some corals have square shaped septa? I'm not so sure about this.

[ynot]

47 minutes ago, Ludwigia said:

Do some corals have square shaped septa? I'm not so sure about this.

Side view in cross section. (?)

Pictures of the top and bottom would help.

[Rockwood]

2 hours ago, Ludwigia said:

Do some corals have square shaped septa? I'm not so sure about this.

 

1 hour ago, ynot said:

Side view in cross section. (?)

Pictures of the top and bottom would help.

In this view they are more often rectangles in my experience.

+1 in the not so sure column.

[TqB]

I agree with side view of tabulate, Favosites sort of thing. There are transverse section hexagons just visible on the left of the second photo.

[Rockwood]

Would the degree of mineral replacement explain the lack of obvious pores in the walls ?

[TqB]

39 minutes ago, Rockwood said:

Would the degree of mineral replacement explain the lack of obvious pores in the walls ?

 

I can see pores in some of the walls when it's blown up a bit.

[JohnJ]

This is not likely a tabulate coral.  Given the location it was found, it is more likely a small, cross sectional fragment of the rudist, Durania. A Forum search should give you several images to compare.

[TqB]

On 9/25/2017 at 7:25 AM, JohnJ said:

This is not likely a tabulate coral.  Given the location it was found, it is more likely a small, cross sectional fragment of the rudist, Durania. A Forum search should give you several images to compare.

 

Drat, should have thought of that!  

[abyssunder]

I agree with JohnJ. It is a rudist fragment.

 

[shel67]

Here are some closeups....

[JohnJ]

1 hour ago, TqB said:

 

Drat, should have thought of that!  

[Rockwood]

Well I'll be ! 

That doesn't happen often.

[shel67]

21 hours ago, DPS Ammonite said:

It looks like Paleozoic tabulate coral. The fossil is probably replaced by silica (does a steel knife blade scratch it?). I don't recall any silicified fossils at NSR except for petrified wood. If it is a tabulate coral which went extinct in the Permain before the Cretaceous, the fossil has been brought in by ancient rivers, human beings or is from reworked gravels from an unknown formation.

 

Please show us what the other sides look like.

 

I was doing a little reading and I came upon this photo of a tabulate coral. Mine looks very much like this especially with the honeycomb shapes on the top. 

[ynot]

I still think it is a tabulate, if that helps.

[shel67]

6 minutes ago, ynot said:

I still think it is a tabulate, if that helps.

I’m very new at this, but from reading and looking at comparisons I have to agree.  My question is....how did this end up in the NSR? 

[DPS Ammonite]

Further examination reveals that this is a tabulate coral and not a rudist. The tabulae (transverse septa) are not lined up from corallite to adjacent corralite. See photo below of tabulae (horizontal east west short lines) that occur in irregular intervals in the corralites (vertical north south tubes):

 

 

Durania have solid calcium carbonate shells. The rectangular "cells" are not hollow. The coral fossil is silicified since a knife blade does not scratch it. I have yet to see any silicified Durania or other fossils in the NSR area except for petrified wood which is probably exotic. The fossil coral shows signs that the rectangular cells were once hollow because they are now lined with many layers of chalcedony (agate). See photo below:

 

 

Below is  a detail photo of Durania austensis from Plano Texas. Note that the horizontal lines (east and west in the photo) all line up in a slightly curving straight line. I believe that they represent growth lines in the rudist. 

 

The transverse sections of the corallites below are hexagonal which strongly suggests coral and not rudists:

 

The real mystery now is not what it is but is how did it get to the North Sulpher River.

 

Possibilities:

Brought in by humans.

Brought in by animals as gastroliths (dinosaurs?).

Brought in by long-gone post-Cretaceous rivers. Fossil was then recycled into the nearby Pleistocene sediments.

 

 

 

 

[shel67]

11 hours ago, DPS Ammonite said:

Further examination reveals that this is a tabulate coral and not a rudist. The tabulae (transverse septa) are not lined up from corallite to adjacent corralite. See photo below of tabulae (horizontal east west short lines) that occur in irregular intervals in the corralites (vertical north south tubes):

Durania have solid calcium carbonate shells. The rectangular "cells" are not hollow. The coral fossil is silicified since a knife blade does not scratch it. I have yet to see any silicified Durania or other fossils in the NSR area except for petrified wood which is probably exotic. The fossil coral shows signs that the rectangular cells were once hollow because they are now lined with many layers of chalcedony (agate). See photo below:

Below is  a detail photo of Durania austensis from Plano Texas. Note that the horizontal lines (east and west in the photo) all line up in a slightly curving straight line. I believe that they represent growth lines in the rudist. 

The transverse sections of the corallites below are hexagonal which strongly suggests coral and not rudists:

The real mystery now is not what it is but is how did it get to the North Sulpher River.

 

Possibilities:

Brought in by humans.

Brought in by animals as gastroliths (dinosaurs?).

Brought in by long-gone post-Cretaceous rivers. Fossil was then recycled into the nearby Pleistocene sediments.

Thank you so much!!! You’ve been extremely helpful!  I’m really proud of this one. So far my oldest specimen! 

[Rockwood]

This happens once in a while.

But not often. 

[TqB]

11 hours ago, DPS Ammonite said:

Further examination reveals that this is a tabulate coral and not a rudist. The tabulae (transverse septa) are not lined up from corallite to adjacent corralite. See photo below of tabulae (horizontal east west short lines) that occur in irregular intervals in the corralites (vertical north south tubes):

Durania have solid calcium carbonate shells. The rectangular "cells" are not hollow. The coral fossil is silicified since a knife blade does not scratch it. I have yet to see any silicified Durania or other fossils in the NSR area except for petrified wood which is probably exotic. The fossil coral shows signs that the rectangular cells were once hollow because they are now lined with many layers of chalcedony (agate). See photo below:

 

Below is  a detail photo of Durania austensis from Plano Texas. Note that the horizontal lines (east and west in the photo) all line up in a slightly curving straight line. I believe that they represent growth lines in the rudist. 

The transverse sections of the corallites below are hexagonal which strongly suggests coral and not rudists:

 

The real mystery now is not what it is but is how did it get to the North Sulpher River.

Possibilities:

Brought in by humans.

Brought in by animals as gastroliths (dinosaurs?).

Brought in by long-gone post-Cretaceous rivers. Fossil was then recycled into the nearby Pleistocene sediments.

 

Nice work.  (A coral gastrolith would be quite something, are there any definite ones?)

 

[Rockwood]

4 hours ago, DPS Ammonite said:

Brought in by animals as gastroliths (dinosaurs?).

Ulcers anyone ?

Could it have been airmailed from the Chicxulub region ? There are some reports of objects that this was the most realistic explanation for I think.

[DPS Ammonite]

I did consider that the coral may have arrived with the giant tsunami from the Cretaceous boloid or comet strike. The wave supposedly went all the way to Kansas. I don't know if any marine Paleozoic rocks exist south of the NSR that could be a source for the coral fossil. Maybe the receding wave might have brought fossiI coral from Oklahoma where silicified coral exists. I think that my other ideas are more likely.

[Rockwood]

Yea, I can hear a little CCR in the background. "Rolling on the river"