South Texas Stromatolite & Coral?

[CraigHyatt]

These finds are from South Texas in Eagle Pass. The surrounding material is soft shale(?) and sandstone(?). I think these are corals and stromatolites, maybe from the cretaceous period. I'd appreciate confirmation. I included a wide shot with my hammer for scale indicating where the "coral" was found. If I can date that location, I might be able to at least estimate dates for layers above and below. This will help me know what kinds of specimens to look for. I'd love to find *anything* with a backbone for a change. You know, so my wife will stop making fun of me. :-)

Edit: After some research I am starting to think the cylindrical fossils are sponges. The egg-shaped fossils might be iron concretions, and the one that looks like a pot might be a mineral concretion. I found an online photo that looks almost exactly like my find: http://www.thefossilforum.com/uploads/monthly_04_2013/post-6208-0-44995700-1365008261.jpg

Wide shot

Possible corals (edit: or sponges)

Possible stromatolite. This is interesting. Almost perfectly round "patty" about 3 or 4 cm thick. Slight depression (0.5 cm to 1.0cm) on one side. (edit: maybe a sponge or echinoderm)

Possible stromatolite. Looks like a pot! (edit: or a mineral concretion like http://www.thefossilforum.com/uploads/monthly_04_2013/post-6208-0-44995700-1365008261.jpg )

Possible stromatolites. Look like dark brown eggs. One of them shown is unbroken. (edit: or iron concretions)

Edited May 1, 2016 by CraigHyatt

[howard_l]

Unless you can see coralites on the end, I am guessing they are burrows. The things you thought were stromatolites are nodules and concreations.

[CraigHyatt]

Thanks, Howard. I looked up "coralite" and it wasn't very helpful. To be clear, do you mean the end of the specimen would be properly terminated (e.g. rounded, pointed) rather than just a broken off segment like I found?

I suppose another characteristic of something living like a sponge or coral would be a regular surface feature. The burrows I found don't seem to have anything like that.

Well, the spot I found looks like a gold mine. I will keep on digging. :-)

[JohnJ]

You are most likely in Upper Cretaceous formations. What other fossils have you found in this location?

[Uncle Siphuncle]

CH

That area is largely Escondido Formation,easiest to recognize for being orange. Look for Sphenodiscus ammonites, gastropods, and turtle frags in the limestones and interceding marl layers. Lots of piano sized slabs of ripple marks in the area too.

[doushantuo]

Craig(if you don't mind the familiarity),your round "patty" is not an echinoderm.

[howard_l]

The coralite is the very end of the coral where you can see the Septa.

If these are from Cretaceous rocks it can't be rugose coral, they were extinct by then.

[CraigHyatt]

I appreciate all the advice. Mainly, I am trying to be more systematic and work in one place. Before, I was just wandering around picking up stuff off the ground. I am also reading various tracts from pubs.usgs.gov, twdb.texas.gov, and lib.utexas.edu and they have lots of helpful photos. Also, of course, reading the basic primers on fossil hunting.

Anyway, I returned to the same area. Here's an overview photo. A lower region of grey, layered clay. An upper region of gold, layered sandstone. Here's a wide shot.

In the lower region all I saw were (apparently) bore holes. These are typical photos.

In the upper sandstone region, things got more interesting. I saw many, many sandstone casts. I believe they are shellfish and snails. The casts are pretty poor quality because of the coarse sand, but I can see striations and whorls in some of the sandstone casts, so I know they are shells. The other thing I saw were dark grey objects. I am not sure if these are shells or fish scales. They are slightly concave and slightly iridescent, but not as shiny as typical mother of pearl.

[Guguita2104]

The coralite is the very end of the coral where you can see the Septa.

If these are from Cretaceous rocks it can't be rugose coral, they were extinct by then.

Howard is right.

Rugosa order became extinc at the end of Paleozoic Era.However, they are often confused with scleractinian solitary corals, commonly known as "stony corals".

Regards,

[doushantuo]

so,basically they get confused only in a very, very bad case of stratigraphic mixing

[CraigHyatt]

Still from the same layer. After looking at many, many samples I found what might be a crab and a turtle shell.

Here's what 99% of the rocks look like. A bunch of fossil sticks.

This might be a crab. At least something with legs.

This might be the inside of a turtle skeleton. The "ribs" run diagonally upper left to lower right in the photo.

[Guguita2104]

so,basically they get confused only in a very, very bad case of stratigraphic mixing

Yes ...Very probably.

[doushantuo]

guguita,are you from the Lusitania area?

[Guguita2104]

guguita,are you from the Lusitania area?

Yes,I'm .

Do you know it?

Edited May 4, 2016 by Guguita2104