What Would You Label These Fossil Burrows?

[LanceH]

OK, what would you label these fossilised burrows as?. Are they worm or crustacean burrows?

I know Thalassinoides and Zoophycus trace burrows run more horizontal whereas these are pretty much all vertical.

The age is Cretaceous about 93 mya I guess and formation is Eagle Ford shale. The burrow lining is very hard like rock, not a recent mud lining.

Edited July 22, 2010 by LanceHall

[jkfoam]

Lance,

Here is how I would Label this fossil

Common Name: Fossil Burrow

Kingdom: Invertebrata

Phylum: Incerta Sedis

Age: Cretaceous

Formation: Eagle Ford Shale

Location: (Where ever you found it)

Comments: Possibly Crab burrow or Worm burrow

This is how I would do it.

JKFoam

[LanceH]

Well I didn't really mean literally what I said in the title sorry. I'm just wondering what they maybe from specifically and didn't want to just say "what are these?" or "worm burrows?" casue that get's old.

I'll settle on worm burrows for now thanks.

I noticed the surrounding matrix is not exactly finely laminated like most Eagle Ford shale but looks some what swirly or stirred up. I'm kind wondering if the surrounding matrix is actually redeposited since the location is right next to a major river. That may make the burrows Pleistocene. I don't know.

Edited July 23, 2010 by LanceHall

[Auspex]

I noticed the surrounding matrix is not exactly finely laminated like most Eagle Ford shale but looks some what swirly or stirred up....

Maybe bioturbation of the (then soft) sediment by the burrow makers themselves?

[hybodus]

Well, back in the day I aways labled the larger ones I have collected with knobby external texture asOphiomorpha isp. Not sure if that would still be correct, so I did a google search against Ophiomorpha = "Description: Ophiomorpha is a branching burrow with either horizontal, oblique, or vertical box-like networks; the burrow exterior is characterized by a knobby texture formed by a pelletal lining, but in some cases only an internal mold of the burrow is evident. Ophiomorpha is interpreted as a combined dwelling and feeding burrow made by a shrimp-like animal; modern callianassid shrimp show the same burrow geometry and pelletal reinforcement of their burrows."

[erose]

Well, back in the day I aways labled the larger ones I have collected with knobby external texture asOphiomorpha isp. Not sure if that would still be correct, so I did a google search against Ophiomorpha = "Description: Ophiomorpha is a branching burrow with either horizontal, oblique, or vertical box-like networks; the burrow exterior is characterized by a knobby texture formed by a pelletal lining, but in some cases only an internal mold of the burrow is evident. Ophiomorpha is interpreted as a combined dwelling and feeding burrow made by a shrimp-like animal; modern callianassid shrimp show the same burrow geometry and pelletal reinforcement of their burrows."

Those same Callianasids (ghost shrimp?) can make smooth-walled burrows like Thallianasoides depending on the matrix they are burrowing into. The round pellet linings are made when the sediment needs reinforcement. The sediments may have been bioturbated prior to the burrowing but still during Eagle Ford time.

But I have to say they sure do look like crawfish burrows so maybe they are not that old.