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Small Rib Bones (?) Teeth (?) In Souris Gravel Pit


cmn85

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My daughter had a school field trip this week to the Souris Agate Pits, a gravel deposit in Southwest Manitoba containing material originating from the Rockies to Hudson's Bay, Paleozoic to Pleistocene. She brought home this piece because she liked the shape. Initially, it just looked like clay, but when I looked closer, it contains what look like three bones or teeth. They're oval in profile, with the ends showing a porous interior. They're lying paralell and decrease in length and diameter from one to the next. There may be more bony material still hidden, but its hard to tell.

Let me know what you think, or if you need other pics/angles.

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I agree with Carl, it's a segment of an ammonite exposing the surface of one septum. Ammonites are rare finds there I believe; when I collected there I found mostly petrified wood, some of it agatized. However, I did find an impression of a bit of an ammonite (Didymoceras) whorl in a piece of "petrified wood" (maybe just a chert nodule). Much of the wood/agate is derived from the Late Cretaceous Riding Mountain Formation as I recall, so an ammonite would be possible. In fact, very few ammonites are known from the Manitoba Late Cretaceous, to judge from the published literature, just a few Baculites and Hoploscaphites. Your specimen clearly does not belong to either of those genera; it may be a bit of a Placenticeras but we'd need to see other views to feel confident of that ID.

Don

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I appreciate the feedback. I can honestly say I wasn't seeing that, but now that you mention it, definite possibility. More views of the same piece are below if it helps. Used a better camera this time.

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Ditto on the wood. Some really nice chunks of petrified wood there. I don't know the taxonomy well, but it wouldn't be the first shelled cephalopod we found in Souris. The one below was found there last summer. I've been told it's a baculite, but I thought it looked too straight for that (granted it's a short section). It's in a pretty good sized chunk of limestone, about 8 inches long, and nowhere near the length of the whole thing. Diameter only changes by 5mm from end to end. Pardon the total lack of preparation. I know nothing about conservation, so I havent done anything to clean the debris out of the impression.

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Carl and Don are good with the ID on your first piece from the initial photo, but with the next couple of photos it becomes obvious that it is ammonite. With the clearer suture pattern someone familiar with the local material may even be able to narrow it down a bit further.

Mike

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Thanks guys. Cool piece considering my daughter kept it with no idea that it was anything but a funny shaped rock.

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