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Fossil hunting in Pueblo, CO


curiouslyjess

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Hi everyone. I have never had a chance to hunt for fossils before but on a recent trip to Pueblo, Colorado my husband and I did some very casual digging at a place popular for finding baculite, and found a few interesting things. I'm hoping that someone can shed some light on what we're looking at.

 

Thanks for any information!

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Well you sure got some baculites for starters.

“...whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been and are being evolved.” ~ Charles Darwin

Happy hunting,

Mason

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Welcome to the Fossil Forum!

I assume you collected at Baculite Mesa?  If so (or anywhere in that area) the long cylindrical fossils are Baculites scotti if they are smooth.  The outcrop is in the Baculites scotti zone of the Pierre Shale, and 99.9% of the Baculites there are that species.  There is a second Baculites, B. texanus, that has strong nodes on the side, but they are very rare compared to B. scotti.

 

It's hard to make out the fossils in the second photo, the image is so close and things are piled up so we can see only a piece of each specimen.  Post a separate photo, or ideally a couple from different angles, for each fossil please.  They look interesting, one may be a Didymoceras which occurs there but is not too common.

 

Don C

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Hi, thanks for your quick responses! Yes, these are all from Baculite Mesa. I tried to take some better pictures, going to attach them here. I really wasn't even sure that the two things I thought were baculite are, I assumed they were but I wasn't going to be surprised if they weren't.

 

So here are two pics of the baculite, and the third picture are things that look like shells? Sorry, that may still not be a great picture. 

 

The fourth and fifth pictures are of what I think you asked for a better pic of. It looked like the two pieces fit together? 

 

In the sixth picture it's hard to tell, but what we think is a fossil is a hard, smoothe, shiny area. You can see one square of a more pearlescent piece on it.

 

Picture seven is similar to six.

 

Thanks!

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The two that fit together are the cast and mold of two ammonite tops.

“...whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been and are being evolved.” ~ Charles Darwin

Happy hunting,

Mason

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5 minutes ago, WhodamanHD said:

The two that fit together are the cast and mold of two ammonite tops.

Aaah, I just looked casts and molds up, that's very interesting! Thanks!

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The top two photos show a pair of fairly typical Baculites scotti.  The next photo shows (top row) specimens of the clam Nymphalucina occidentalis.  These are abundant in the teepee buttes (conical mounds seen around the base of Baculite Mesa).  The next two photos show a nice specimen of Didymoceras, a heteromorphic ammonite also found associated with the buttes.  It's not totally straightforward to ID species of Didymoceras and multiple species occur in the B. scotti range zone so I'll leave this one at the genus level.  The second to last photo is an Inoceramus clam; not enough detail is present for a confident species ID.  The last photo shows a piece of a Baculites and a Nymphalucina.

 

The "teepee buttes" are conical mounds of carbonate (limestone) that formed around methane seeps in the Cretaceous sea floor.  The surrounding rock is shale, often with carbonate concretions with fossils inside.  The methane seeps provided energy for methane-fixing bacteria, which provided an abundant food supply for other organisms.  The bacteria also provided conditions to precipitate carbonate and together with the clams, tube worms (which you can see in thin sections but generally not in the coarse rock), and likely other organisms, form the structure of the mound.  It is thought that the Nymphalucina and Inoceramus clams were also able to cultivate bacteria in their "mantle" (the living tissue you see when you open the shells of a clam).  With very careful collecting and considerable luck you might also find some crabs that also occupied this unique habitat.  During the Late Cretaceous, these methane seeps would have provided "oases" able to support a diversity of species, whereas the surrounding mud sea floor (now shale) would have been almost devoid of life.  The fossils that are found in concretions in the shale did not actually live on/in the sea floor (with rare exceptions), but rather lived in the water column above and settled to the bottom after death.

 

Here is a link to an interesting paper about the teepee buttes.

 

Don

 

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That's very interesting, thank you! 

 

I also just pulled this one out of what we collected, the more I looked at it the more interesting I thought it was. I'm attaching pics of multiple angles, is it a fossil too?

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