Bryozoan On Inside Of Baculite Living Chamber

[Plax 615]

couldn't decide whether to post this to ID or general discussion. Would be curious to have an ID on this but the interesting thing is its position and growth habit. The bryozoan is growing on the inside of a baculite living chamber. No aragonitic preservation in the Peedee so the shell of the baculite is gone, leaving the bottom of the bryozoan colony exposed. The radial growth is also interesting. Can't say I've ever noticed that before but it may be common. Baculite fragment is 40x25mm. Fossil was found in the loose arenite of the Rocky Point Member of the Peedee Formation, late Cretaceous, Maastrichtian. Pender Co., NC, USA

[Auspex 3,602]

What a great fossil!

[erose 886]

That is really a cool fossil.

[the tatter 5]

WOW that is a nice one

[Plax 615]

not mine, collected by the Fossil Foilist group

It's as smooth as glass which is what lead me to the upside down conclusion. If it had been on the outside of the shell it would have been loose with the aragonite gone. All we would have had was the baculite steinkern. A rare find on its own in the Peedee.

[Bev 220]

Congrats!

[Ludwigia 3,442]

Cool! I guess it moved in after the baculite left, or do you think they coexisted?

[Plax 615]

I'd say after the ammonite was dead. Am assuming the living chamber was tightly filled with the animals body in life. Don't know for sure though. Thanks for looking folks! Not exactly a popular fossil group.

[sixgill pete 1,411]

Very cool. Skylar and his "posse" have found some very awesome interesting and cool fossils recently.

[Plax 615]

Persistence pays!

[non-remanié 205]

I have seen a couple examples from the Campanian Wenonah fm. of NJ of bryozoan impressions on Placenticeras minor steinkerns. Very similar. I believe I have also seen it on a baculite but not quite sure of that. It wasn't anywhere as impressive as this specimen if I do recall things correctly. But one of my Placenticeras with bryozoan encrustation is pretty nice. I'll try to post a picture of it here if I have time.

[Plax 615]

is that the placenticeras species from the siderite concretions at Big Brook? Have been wondering what to call it. I don't recall any bryozoan on mine but I didn't look at things the same way 20 or 30 years ago.

[non-remanié 205]

Yes, those are P. minor, by far the most common ammonite in the Wenonah formation. My specimen with the bryozoan is from Ramanessin Brook and has phosphatic preservation, though. Still working on a pic... but I'll get to it!

[non-remanié 205]

this guy has an interesting history although im not completely sure of the timeline...

[non-remanié 205]

[Plax 615]

those bryozoa look like "outies". Wonder how they stayed in place with the shell gone. Guess the sediment filed the void as the shell dissolved? Is that a burrow structure or the mold of a heteromorph ammonite? Oxybeloceras comes to mind but am away from references. A very interesting specimen all around!

[non-remanié 205]

Yes this piece is a little more interesting than I even had remembered. I'm glad I took it out for another look. I believe it is an uncoiled ammonite mold, and was also thinking Oxybeloceras, but they have never been found in NJ, only in the Mt. Laurel at the C&D Canal. It might also be a part of a Didymoceras perhaps. I guess I could make a positive impression of it and that might help it be IDed, but I think we're on the right track. I guess both of these "guests" must have made it into a dead, empty Placenticeras shell before it was buried and filled with sediment.

[Plax 615]

have always liked combo fossils as they provide more entertainment speculating on how they got together, thanks for showing this one!

[The Jersey Devil 326]

On 11/5/2013 at 2:18 PM, non-remanié said:

Yes this piece is a little more interesting than I even had remembered. I'm glad I took it out for another look. I believe it is an uncoiled ammonite mold, and was also thinking Oxybeloceras, but they have never been found in NJ, only in the Mt. Laurel at the C&D Canal. It might also be a part of a Didymoceras perhaps. I guess I could make a positive impression of it and that might help it be IDed, but I think we're on the right track. I guess both of these "guests" must have made it into a dead, empty Placenticeras shell before it was buried and filled with sediment.

 

Does that mean a heteromorph somehow got inside of the Placenticeras shell? That would be strange. Excellent specimen!

[dalmayshun 142]

beautiful fossil, interesting discussion. thanks.