Lockatong Trace Fossil

[hitekmastr]

Happly Holidays to everyone and all the best for 2013...

Here's a trace fossil from our last Fall fossil trip - Lockatong - Triassic - not sure what this pattern represents. The rock is about 1 foot wide.

Here are some additional photos including a shot of the full rock, and some angles that show the thickness of the trace material and may give some clues to the consistency, etc. The opinions on what this might be are very interesting - as for me, I have absolutely no clue...

Edited December 21, 2012 by hitekmastr

[Auspex]

Gnarly! The rock looks pretty tortured; is there a clear plane of bedding, or is it all stirred up?

[piranha]

It reminds me of this interpretation of a tunnel system:

[Plax]

or mud cracks

[hitekmastr]

I'll take a few more photos.

[erose]

or mud cracks

I think this is a good bet as well.

[Indy]

There is another possibility ...

I live in the Pennsylvanian ... so take that as a disclaimer

Your specimen reminds me of "Root molds" I've found

not exactly the same ... but similar.

Here's a couple images for comparison: LINK

In the posted picture ... I think I also see what could be

interpreted as smaller rootlet features.

Of course, Scott's suggestion in post #3 makes sense also

Edited December 18, 2012 by Indy

[phytosaur]

Depending on the position of the bedding plane, a rock like this in the Lockatong is going to be interpreted as mud cracks, or root casts filled by mud.

Edited December 18, 2012 by phytosaur

[tracefossilnut]

This is Thalassinoides, the combined feeding and dwelling trace of an arthropod.

[hitekmastr]

If that's the I.D. - and it looks like it from the Internet imagery - this is what the creature that made it would look like:

Thalassinoides is a complex trace fossil that is today made primarily by thalassinidean crustaceans (a type of shrimp). Burrows are made today by shrimp today, and paleo-experts are learning more about how ancient tunnel systems were excavated. This sample from the Lockatong Formation in Pennsylvania would be from the Triassic.

[phytosaur]

There are no thalassinidean crustacean fossils in the newark basin - it was a fresh water system, not marine. This is either mud cracks or root molds. most of the bioturbation in the newark group is done by roots.

-Ben

[Fossildude19]

There are, however, reports of the ichnofossil Scoyenia in the Newark Supergroup.

That said, I am inclined towards root casts or mudcracks.

Regards,

[Missourian]

Could you take photos of the sides?

[TheFossilHunter]

Mud cracks

[hitekmastr]

The traces are not deep like a tunnel, they are very "thin" which may suggest mud as you can see in the side view of the first photo - which shows how thin it is. Don't know if this is helpful....