OregonFossil Posted January 29, 2021 Share Posted January 29, 2021 Normally this sandstone is filled with bivalves and snails of various species in the loosely consolidated. The "rust" color almost always is a biological marker in this sandstone. All of the bivalves and gastropods have that coloration. This specimen was found when a smallish piece of sandstone was separated in half. This half has the "head" I think, the other part has most of the cast of the body (this whatever it is, is bilaterally symmetrical). The only paper I have does not mention annelids. Anyone want to take a guess what this is, sending it to a "real" paleontologist to get an opinion. Link to comment Share on other sites More sharing options...
Top Trilo Posted January 29, 2021 Share Posted January 29, 2021 possibly a burrow Edit: you say trace fossil so are you asking worm burrow or worm? “If fossils are not "boggling" your mind then you are simply not doing it right” -Ken (digit) "No fossil is garbage, it´s just not completely preserved” -Franz (FranzBernhard) "With hammer in hand, the open horizon of time, and dear friends by my side, what can we not accomplish together?" -Kane (Kane) "We are in a way conquering time, reuniting members of a long lost family" -Quincy (Opabinia Blues) "I loved reading the trip reports, I loved the sharing, I loved the educational aspect, I loved the humor. It felt like home. It still does" -Mike (Pagurus) “The best deal I ever got was getting accepted as a member on The Fossil Forum. Not only got an invaluable pool of knowledge, but gained a loving family as well.” -Doren (caldigger) "it really is nice, to visit the oasis that is TFF" -Tim (fossildude19) "Life's Good! -Adam (Tidgy's Dad) Link to comment Share on other sites More sharing options...
LabRatKing Posted January 29, 2021 Share Posted January 29, 2021 Wait worms!?!? What!?!? First, need some location formation Link to comment Share on other sites More sharing options...
OregonFossil Posted January 30, 2021 Author Share Posted January 30, 2021 Sorry that was a copy of a post I made to our meetup group. This is from the Pittsberg Bluff formation in NW Oregon. Here is someone seconding my take on it being a trace fossil of a worm burrow (I don't think it is a cast): Nice! Looks like it may be a burrow, possibly a lined burrow, filled with finer sediment than the matrix around it. The reddish area around the edges looks like the iron in the coarser sediment was oxidized, forming a rusty "halo" effect around the burrow. This can happen when the animal(s) that made the burrow dig into sediment that is not well-oxygenated. If an animal digs into a layer that is not well-oxygenated, the water in the burrow has more oxygen than the surrounding sediments and over time, can oxidize the sediment. Do you know what age/Formation? Better images (from 80 mb files, but you have to flip one to get the orientation with the other (greater detail). Link to comment Share on other sites More sharing options...
OregonFossil Posted January 30, 2021 Author Share Posted January 30, 2021 Sorry that was a copy of a post I made to our meetup group. This is from the Pittsberg Bluff formation in NW Oregon. Here is someone seconding my take on it being a trace fossil of a worm burrow (I don't think it is a cast): Nice! Looks like it may be a burrow, possibly a lined burrow, filled with finer sediment than the matrix around it. The reddish area around the edges looks like the iron in the coarser sediment was oxidized, forming a rusty "halo" effect around the burrow. This can happen when the animal(s) that made the burrow dig into sediment that is not well-oxygenated. If an animal digs into a layer that is not well-oxygenated, the water in the burrow has more oxygen than the surrounding sediments and over time, can oxidize the sediment. Do you know what age/Formation? Link to comment Share on other sites More sharing options...
OregonFossil Posted January 30, 2021 Author Share Posted January 30, 2021 Second image, again you have to invert one or the other to get an orientation match Link to comment Share on other sites More sharing options...
OregonFossil Posted January 30, 2021 Author Share Posted January 30, 2021 Second PRO response (BTW trace is Parallel to layers): This looks like a burrow of some sort that was subsequently infilled by finer grained sediments. I cannot be sure what the orientation of this structure is-- Jeff was it parallel to or perpendicular to the bedding plane? If parallel it could be, as you say, some form of annelid burrow trace. If perpendicular, it could be infilling of the siphon cavity in the sediments from your aforementioned bivalves. The last possibility is that there are the infilled burrows of tunneling decapods. I have worked in similar Paleogene marine environments where these are very common. The small scale and slight ribbing on the margin suggests that is unlikely, however. Link to comment Share on other sites More sharing options...
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