Grayson county Texas brachiopod? ID

[KimTexan]

My daughter asked me to take her fossil hunting today. She has never asked me to take her before so I was excited to take her out. She’s only 13.

We drove up to Grayson County where I knew we would be sure to find something. We went to a creek where there were about 4-5 different formations or layers visible. Near the top though was a red layer. I didn’t find anything of interest in the red layer while in the creek. But when we returned to the car I decided to look around at the hillside and found something I didn’t expect to see there.

 

I have been to this creek before. It has more oysters than I’ve ever seen in my life. It has a few varieties of ammonites and some echinoids and Inoceramus clams and that is about it.

Next to where I parked my car there was a drainage ditch with red dirt and sitting there in the drainage ditch was this cluster of brachiopods.

I would appreciate it if anyone could tell me what they are. One side of the cluster is red.

This is the red side. The largest one is about 4 cm wide.

[Ludwigia]

Those aren't brachiopods, but rather bivalves. Couldn't tell you which ones, though.

[Tidgy's Dad]

Yes, bivalves.

Pholadomya sp?

[KimTexan]

I never can tell a brachiopod from a bivalve in these situations. None of them seem to have a full valve and none have both valves so I can’t tell where the plane of symmetry is. I guess I don’t see a foramen either, but I often can’t see those even in brachiopods. Granted I was in the Cretaceous so I guess the rule to go by must be If in the Cretaceous it’s a bivalve.

@Ludwigia So what indicates to you they are bivalves?

I wish I could figure out where they came from. They were high above where I had found clams, ammonites, oysters and echinoid. The preservation of detail is the best I have ever seen in the area. If they came from a similar mass to the oysters I want to see it.

Here you can see some of the masses of oysters. Some on this slab are pink and maroon. 

The slabs are massive, some the size of cars.

In this pic you can see an oyster slab. The oysters go through the layer almost a foot deep. Behind it is what appears to be a lobster burrow or something. Behind it is another burrow I had not seen before that has a bubble appearance.

Here is another similar shot.

This is a close up of one of the burrows. You can also see the underlying formation is a soft black shale.

Here is the other form of burrow below.

The slabs were massive. This one was maybe 8 feet long by 5 feet high. It also has the oyster encrustations. Could this be crab burrows.

I wonder what the likelihood would be of a crab or lobster being preserved somewhere in one of these is.

Here you can see a shot of the creek bank strewn with slabs. They almost look like concrete. I think 1-2 May have been concrete, but most were slabs of oysters. Texigraphaea looking.

I think it was 2 years ago we had enormous amounts of rain in the summer. It was a record amount of rain that brought lakes up several feet. I am guessing the rains caused flooding here and broke these slabs free. The creek is actually about 10 feet below where I’m standing. When we were up on the bank there was debris from flooding in the trees 3-4 feet above my head.

I can’t see a red layer in the creek on this bank, but the other side of the creek has a red layer above the creek bank.

[Tidgy's Dad]

Brachiopods have two valves which are different sizes and shapes (mostly), bivalves usually have two very similar valves, but each valve is not bilaterally symmetrical as is the general rule with brachiopods. 

These specimens look like this: 

And the one side of the valve is quite extended. 

[FossilDAWG]

I think Pholadomya is a reasonable suggestion.

 

Don

[Ludwigia]

3 hours ago, KimTexan said:

 

@Ludwigia So what indicates to you they are bivalves?

 

As Tidgy's Dad already mentioned, the shells are asymmetric as opposed to brachiopods, which are symmetric. I also find Pholadomya to be a pretty good guess.

[Plax]

rocks look like quarried, hauled in rip-rap. It's used in erosion control. If you don't see any of the rock away from roads or habitations it is probably not from there. Those are huge burrows! Flaggy rock like this is ideal for the quarryman to use in this application.

  On second thought your last pic does look like native horizontal beds. The chaotic orientation of the rocks and dissimilarity to each other in the other photos make me think rip-rap.

Edited December 18, 2017 by Plax
second thoughts

[Peat Burns]

 

Image from Kansas Geological Survey

[abyssunder]

These trace fossils look to be Thalassinoides burrows.

 

[doushantuo]

I couldn't resist this:

richthofeniid brachiopods:

rudist bivalve:

[KimTexan]

8 hours ago, Plax said:

rocks look like quarried, hauled in rip-rap. It's used in erosion control. If you don't see any of the rock away from roads or habitations it is probably not from there. Those are huge burrows! Flaggy rock like this is ideal for the quarryman to use in this application.

  On second thought your last pic does look like native horizontal beds. The chaotic orientation of the rocks and dissimilarity to each other in the other photos make me think rip-rap.

It is definitely coming out of the formation in the bank. These slabs are basically in situ having just fallen from the creek bank. Here is a shot of the bank maybe 30 feet upstream from where the slabs of burrows were. This is part of a burrow in situ with oyster layers above and below the burrow.

I believe there is some concrete present as well, but it is the minority of slabs. Further down the creek are 2 enormous corrugated metal culverts they must have placed for erosion control, but they’re washed out of place. They look like they were 10-12 feet in diameter. I didn’t make it that far down the creek to see how big they were. The opposite bank is an avalanche or mudslide waiting to happen with the next heavy rain. 

The clams are probably from near the area I found them in. The soil was all red and iron laden as is this cluster.

7 hours ago, abyssunder said:

These trace fossils look to be Thalassinoides burrows.

 

I agree about the ones in the front. What about the ones behind them?

[doushantuo]

lowermost:bivalve,mantle not shown for clarity

 

 

[Plax]

15 hours ago, abyssunder said:

These trace fossils look to be Thalassinoides burrows.

 

I was thinking the same thing Abyssunder but the scale (5x8 foot slab) is huge for those I've seen previously. Am agreeing with you but pointing out the scale. The individual burrow width would be near a foot by my estimation.

[oldtimer]

I think that I would have to break open some of those burrows to see if there is something to be found in them.

Glad you and your Daughter got out for the hunt.

[JohnBrewer]

12 hours ago, doushantuo said:

I couldn't resist this:

richthofeniid brachiopods:

rudist bivalve:

Making mischief methinks. 

[abyssunder]

4 hours ago, Plax said:

I was thinking the same thing Abyssunder but the scale (5x8 foot slab) is huge for those I've seen previously. Am agreeing with you but pointing out the scale. The individual burrow width would be near a foot by my estimation.

I would not exclude the scale. Some of the Thalassinoides burrows are huge.

 

picture from here

 

 

[Plax]

amen brother!

[sixgill pete]

2 hours ago, abyssunder said:

I would not exclude the scale. Some of the Thalassinoides burrows are huge.

 

picture from here

 

 

 

All I can say is dang!

[Nimravis]

Nice trip report and some cool finds.