Bigby-Cannon Limestone

[Terri]

Cool! Thanks Tony, it's not too bad for a 460(ish) million year old fossil!

 

[Terri]

Haven't been back to this location in a while, I'm anxious to go back before the weather gets bad, I did find this orthocone last time I was there, I find little suprises going through the fossils on my picnic table from time to time. Kind of hard to id. cant see the siphuncle and there's a lot of goo. Fairly closely spaced septa, maybe Ellesmerocerad?

 

[DWhatley]

Prehistoric underwater termites at work on the right half?

 

[Terri]

I'm thinking Trypanites (worms again). It's kind of odd they just bored into the soft stuff.

 

[DWhatley]

I wonder if the worm holes are more present day happenings rather than historic.

 

[Terri]

I was thinking the same thing the white stuff is sort of soft, almost like chalk, I've seen it on fossils before but I'm not sure what it is. Kevin probably knows. I think I'll try scraping some of it off tommorrow.

 

[Architeuthoceras]

I don't know which filled the chambers first, the white stuff, or the gray stuff. The gray stuff looks like the matrix of the main rock, so it probably filled some broken chambers. The white stuff is different, and it looks like it filled the chambers completely, so those chambers were probably not broken. The question is whether the chambers were filled just after the animal died or after the shell was buried for a while. I don't know of any worms that drill rock in Tennessee, so the holes were probably made before the white stuff was lithified. There also seems to be a few holes right around the white stuff in the gray stuff so it was all probably soft when the holes were drilled.

More study needed

 

[Terri]

There also seems to be a few holes right around the white stuff in the gray stuff so it was all probably soft when the holes were drilled.

Yes, I noticed that last night when I was taking a closer look after D's question, I scraped around a little on one of the chambers and it is soft but if I scrape it all off the interesting holes will be gone. I think they do look a lot like Trypanites borings. The white stuff is really chalky in texture, any ideas on what it is, I browsed around some but didn't come up with anything conclusive, some sort of phosphate? Is any form of phosphate that soft?

 

[Terri]

Same white stuff in the chambers of the fossil in post #87.

 

[DWhatley]

chalky like dusty or more like clay?

 

[Terri]

Maybe a cross somewhere between the two, not maleable like clay though.

 

[Architeuthoceras]

Maybe the shell was buried with a few broken chambers filled with the gray stuff, and a few of the complete chambers filled with x... Later the shell and/or mold was re-exposed, and a different mud filled the remaining chambers...

 

[Terri]

I haven't been out hunting in a while but still going through photos and looking at stuff I've drug home..I think this is a little orthocone, it seems to be totally crystalized inside and out but does show a few septa, probably not possible to id. but kinda cute and one of the few remaining cephs in my stash...

 

[Architeuthoceras]

Nice little orthocone

 

[tonmo]

one of the few remaining cephs in my stash...

Time for a new expedition!