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A Visit to the Fox Hills fm. - Eastern Colorado


Brett Breakin' Rocks

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Brett Breakin' Rocks

Finally ... a short trek on the open prairie of Eastern Colorado and into a slice of the Cretaceous period. This was my first true jaunt since my move from the East coast and it was a welcome change to my normal routine. My journey really began several years ago when I purchased some shark teeth from a fossil forum member in Colorado. He regularly visits a site on private land in Eastern Colorado that contains (what we think) are exposures of the Fox Hills fm. , and are chock full of marine fossils from that time period. 

 

I contacted him several weeks after I arrived, desperate to get away from civilization, and honestly just looking for someone I can chat with about geeky fossil stuff. The rolling hills of harvested wheat and corn stretched as far as the eye could see.... 

 

120240217_404653187600150_5812590311726291312_n.thumb.jpg.cdcdb5570aae198421b6b651e30e1eb4.jpg

120107175_1035941710161615_6915791610256014618_n.thumb.jpg.8dbaf4097e11566b59eb5bf7cbeeec75.jpg

 

The exposure with the most fossil concentrations sat in a rust colored band of loose sand/sandstone. The best pockets contained shells where the teeth and bone settled. I was there without most of my usual equipment. I wasn't sifting or digging for much more than an hour before we had to leave and came home with plenty of matrix and fossils to keep me busy for several weeks. 

 

120017377_2510696005887434_5258849329075462447_n.thumb.jpg.47feaa5afab9a5df181e1a3cc80fe6e9.jpg

120121143_905793489946917_6418469729291888765_n.thumb.jpg.bb0bb72eac1eb9b4054a52706ad2ccb8.jpg

 

Shrimp-like trace fossils.

120189471_313341953298136_7795331730552349969_n.thumb.jpg.029aa6ea0ffdb1d05b935b880f567fea.jpg

 

As well as Squatina sp. and Sand Tiger Shark, Carcharias sp. teeth .. as well as small fish teeth, small fish vertebra etc. can be found. Good thing he had some small screens or all of these wonderful finds would still be on the sandy slope. Average size for these shark teeth is about 10mm.

 

120230814_828436031230040_1184391252911713660_n.thumb.jpg.33ad71011e57c750876e1b9862af2287.jpg120196786_335742474361847_6173166646705798931_n.thumb.jpg.7af6af7344a33f36285d4b617cfc1758.jpg120367117_349266379820459_1065368970732219859_n.thumb.jpg.2224de761e33d2a52edc3f013466ed92.jpg 120197575_1255500598145479_2619078731832401791_n.thumb.jpg.c7e05936eebdff74ce76619e7af67acc.jpg120262377_335061161060243_4691477407498124040_n.thumb.jpg.81ba16ffc1747a8b0119b729f2a2b687.jpg

 

Cheers,

Brett

 

PS. I'll wash the matrix and post any additional micro-fossils here. 

 

 

 

 

 

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Brett Breakin' Rocks

Here are some teeth that are also from the same location. 

 

01_FoxHills_Cretaceous_012019.thumb.jpg.50b64ea23d2ecde101d93eed7438b99c.jpg02_FoxHills_Cretaceous_012019.thumb.jpg.b7a8b5272b1215041ce1cdb8506b2dfe.jpg

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When I read "Fox Hills", I was expecting to see ammonites, but instead you've shown us teeth. Something new for me. This must be a different zone than where the ammos come from. Or is the sedimentation completely different in this area? Thanks for posting.

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Great report, Brett!

Thanks for posting these awesome teeth.  :) 

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6 hours ago, Ludwigia said:

When I read "Fox Hills", I was expecting to see ammonites, but instead you've shown us teeth. Something new for me. This must be a different zone than where the ammos come from. Or is the sedimentation completely different in this area? Thanks for posting.

Thanks, you know .. I think that initial determination was made when he first discovered the site and posted it here on the forum.  That being said I'm not sure if that was verified (?) That's why it is still a bit up in the air. He did donate a large quantity of Chimaera fossils. I'll dig around and see if the paper that was written or is in progress has any information. 

2 hours ago, Fossildude19 said:

Great report, Brett!

Thanks for posting these awesome teeth.  :) 

Thanks Tim, they are some of my favorite. That deep red color is just amazing.

2 hours ago, RJB said:

Great report and great pictures too. 

 

RB

Thanks man .. one day I hope to grow up just as cool as you. I'm trying. haha  

 

1) First I need a fossil SHED .. I can crawl around in .. 

2) Ask wife for a fossil shed.

 

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17 minutes ago, Brett Breakin' Rocks said:

Thanks, you know .. I think that initial determination was made when he first discovered the site and posted it here on the forum.  That being said I'm not sure if that was verified (?) That's why it is still a bit up in the air. He did donate a large quantity of Chimaera fossils. I'll dig around and see if the paper that was written or is in progress has any information.

Thanks. That would interest me.

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Great report! Those are some gorgeous teeth.

 

Thanks for the site and process photos. That looks like good dirty fun :)

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Nice report.  Any chance we could see some of the invertebrate fossils from the site?  BTW those "corn cob" looking things are pieces of Ophiomorpha burrows, which are believed to be made by crayfish or similar decapods.

 

Don

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1 hour ago, FossilDAWG said:

Nice report.  Any chance we could see some of the invertebrate fossils from the site?  BTW those "corn cob" looking things are pieces of Ophiomorpha burrows, which are believed to be made by crayfish or similar decapods.

 

Don

Yeah, and these things are one of the more common fossils in the Fox Hills Fm that I have explored in Wyoming.  

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3 hours ago, Brett Breakin' Rocks said:

Thanks, you know .. I think that initial determination was made when he first discovered the site and posted it here on the forum.  That being said I'm not sure if that was verified (?) That's why it is still a bit up in the air. He did donate a large quantity of Chimaera fossils. I'll dig around and see if the paper that was written or is in progress has any information. 

 

See if this helps.

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11 minutes ago, JohnJ said:

Nice .. thanks ! .. And just to update, I did find the paper co-authored by Mike Everhart (Sternberg Museum of Natural History) concerning this site, and have confirmed that it is a Fox Hills fm. Late Cretaceous period. I always err on the side of caution when it comes to time periods. I don't like to be certain when I don't yet have all of the information. 

 

Thanks again. 

 

Cheers,

Brett

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1 hour ago, FossilDAWG said:

Nice report.  Any chance we could see some of the invertebrate fossils from the site? 

Hi @FossilDAWG Don, I'll take some shots of what survived (I'm assuming you were referring to the bivalves ?). I didn't have a ton of time so I grabbed what I could and the shells were super fragile. Those that did survive were covered in some sort of hard calcite crystals .. or something like selenite (precipitate minerals) ? The rest crumbled to a chalky dust. My assumption is the acidic soil ? .. creates a harsh environment. 

 

Cheers,

Brett

 

I know .. not the best photos in the direct lighting but a good deal of the surface texture is lost for most if not all of these. I'll have to check what sits in my other matrix pieces. You can see a bit of fish spine in here as well. 

120189091_2765529350382680_8923543906890917880_n.thumb.jpg.832f4832c1c30721e1d176cb5b5b31da.jpg

 

120187474_265912197884607_2290727386696306958_n.thumb.jpg.604d00b11aa5ee952e46e79cde11f682.jpg

 

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Looks like it could be selenite.  Unfortunately it makes it impossible to ID the bivalves.  It would probably have been almost impossible anyway, inoceramids would be expected to be most common, and many species are very similar and very hard to distinguish from photos.  When they can be identified, they can be almost as good as ammonites to narrow down an age/biozone.

 

Don

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20 hours ago, JohnJ said:

Hadn't seen this map previously. Surprised at the detail. It even has the tiny Castle Hayne Limestone outliers showing here in NC. Thanks!

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On 9/28/2020 at 3:37 AM, Brett Breakin' Rocks said:

Finally ... a short trek on the open prairie of Eastern Colorado and into a slice of the Cretaceous period. This was my first true jaunt since my move from the East coast and it was a welcome change to my normal routine. My journey really began several years ago when I purchased some shark teeth from a fossil forum member in Colorado. He regularly visits a site on private land in Eastern Colorado that contains (what we think) are exposures of the Fox Hills fm. , and are chock full of marine fossils from that time period. 

I contacted him several weeks after I arrived, desperate to get away from civilization, and honestly just looking for someone I can chat with about geeky fossil stuff. The rolling hills of harvested wheat and corn stretched as far as the eye could see.... 

120240217_404653187600150_5812590311726291312_n.thumb.jpg.cdcdb5570aae198421b6b651e30e1eb4.jpg120107175_1035941710161615_6915791610256014618_n.thumb.jpg.8dbaf4097e11566b59eb5bf7cbeeec75.jpg

The exposure with the most fossil concentrations sat in a rust colored band of loose sand/sandstone. The best pockets contained shells where the teeth and bone settled. I was there without most of my usual equipment. I wasn't sifting or digging for much more than an hour before we had to leave and came home with plenty of matrix and fossils to keep me busy for several weeks. 

120017377_2510696005887434_5258849329075462447_n.thumb.jpg.47feaa5afab9a5df181e1a3cc80fe6e9.jpg120121143_905793489946917_6418469729291888765_n.thumb.jpg.bb0bb72eac1eb9b4054a52706ad2ccb8.jpg

Shrimp-like trace fossils.

120189471_313341953298136_7795331730552349969_n.thumb.jpg.029aa6ea0ffdb1d05b935b880f567fea.jpg

As well as Squatina sp. and Sand Tiger Shark, Carcharias sp. teeth .. as well as small fish teeth, small fish vertebra etc. can be found. Good thing he had some small screens or all of these wonderful finds would still be on the sandy slope. Average size for these shark teeth is about 10mm.

120230814_828436031230040_1184391252911713660_n.thumb.jpg.33ad71011e57c750876e1b9862af2287.jpg120196786_335742474361847_6173166646705798931_n.thumb.jpg.7af6af7344a33f36285d4b617cfc1758.jpg120367117_349266379820459_1065368970732219859_n.thumb.jpg.2224de761e33d2a52edc3f013466ed92.jpg 120197575_1255500598145479_2619078731832401791_n.thumb.jpg.c7e05936eebdff74ce76619e7af67acc.jpg120262377_335061161060243_4691477407498124040_n.thumb.jpg.81ba16ffc1747a8b0119b729f2a2b687.jpg

Cheers,

Brett

PS. I'll wash the matrix and post any additional micro-fossils here.

Nice fossils Brett, thank you very much to show us this.

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19 hours ago, bthemoose said:

Great colors on those teeth!

 

19 hours ago, henpecked said:

Thanks for sharing your pictures and welcome to Colorado 

 

48 minutes ago, fifbrindacier said:

Nice fossils Brett, thank you very much to show us this.

Thanks everyone .. this is my second favorite site for tooth color after Bone Valley ... ok and Summerville .. ahh and Virginia/Carolina copper and red. Hmm, actually it's hard to choose really. 

 

Cheers,

Brett

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A couple micros after cleaning the matrix. 

Fox_Hills_09_26_2020_Micros_001.thumb.jpg.01d0de2b255c90ccab9f6f3dd33df6c4.jpg

 

Hey @MarcoSr have you ever seen something like this ? ... it looks like a molar ?  I've read that one rodent tooth was found at the site, a multituberculate (Mesodma
formosa).. or is it possibly just a fish tooth with roots, and my eyes are playing tricks on me. Small rodent teeth are not my specialty. 

Fox_Hills_09_26_2020_Micros_002.thumb.jpg.2f1df39d71690564ed7f6fa279530bca.jpg

 

Rhinobatos sp. perhaps (?)

Fox_Hills_09_26_2020_Micros_003.thumb.jpg.0eee37834279aaa56f673106af4ca334.jpg

Cheers,

Brett

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13 hours ago, Brett Breakin' Rocks said:

.. it looks like a molar ?  I've read that one rodent tooth was found at the site, a multituberculate (Mesodma
formosa).. or is it possibly just a fish tooth with roots, and my eyes are playing tricks on me. Small rodent teeth are not my specialty. 

Fox_Hills_09_26_2020_Micros_002.thumb.jpg.2f1df39d71690564ed7f6fa279530bca.jpg


It looks like a Multituberculate tooth. Very nice find. Not related to rodents though, the first rodents appeared well after the end of the Cretaceous.

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13 hours ago, Brett Breakin' Rocks said:

 

Hey @MarcoSr have you ever seen something like this ? ... it looks like a molar ?  I've read that one rodent tooth was found at the site, a multituberculate (Mesodma
formosa).. or is it possibly just a fish tooth with roots, and my eyes are playing tricks on me. Small rodent teeth are not my specialty. 

Fox_Hills_09_26_2020_Micros_002.thumb.jpg.2f1df39d71690564ed7f6fa279530bca.jpg

 

Rhinobatos sp. perhaps (?)

Fox_Hills_09_26_2020_Micros_003.thumb.jpg.0eee37834279aaa56f673106af4ca334.jpg

Cheers,

Brett

 

Brett

 

Really nice pictures.  I agree with Eric that the first tooth above looks like a Multituberculate tooth, definitely not a fish tooth.  Nice specimen!  Is your scale correct on the second tooth?  The tooth looks like an Orectolobiforme tooth.  The features shown look like a Chiloscyllium sp. tooth but their max size (for C. greeni which is common in a lot of US Cretaceous Cenomanian-Coniacian Formations) is around 1.8 mm Welton 1993.

 

There are a good number of Cretaceous ray species teeth that can be as small as .4 mm.  If you use window screen as your smallest screen mesh size (usually around 1.75 mm) you will miss a lot of these ray teeth.  There are also species of Creataceous shark teeth and a good number of bony fish species teeth that will fall through window screen.  Unless they have been wicked away by water action, there are usually many more of these small teeth than the larger teeth that you can easily see with the naked eye.

 

Marco Sr.

 

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5 hours ago, MarcoSr said:

Really nice pictures.  Is your scale correct on the second tooth? 

Hi Marco,

 

The images were created using a flatbed scanner. The second tooth, yes, it's a little over 5mm, and my equipment has much to be desired. We just moved and I'm not set up (well, never have been set up for micros), I need a serious set of specs or a large lamp with a magnifier.

 

 120433212_380862692929695_7666442242416714750_n.thumb.jpg.d812dcffb36baa0ac3272a0da2e21fda.jpg

5 hours ago, MarcoSr said:

If you use window screen as your smallest screen mesh size

The mesh isn't quite as large as a window screen, I hit up my local Korean market (my wife is half Korean) and found a decent enough screen used for veggies I believe. Sub millimeter .5-1 ? .. but not anything as fine as you mention. I do however have a 'catch' beneath it after washing the matrix ... juuust in case something else decides to slip by. But like you said, I may have lost some in the washing method and I'll need a good microscope to see anything beyond that. 

120323288_2745341249082619_464709727953741594_n.thumb.jpg.e919f09805019f1a2a88b269ffe1cfcb.jpg

 

Thanks for the guidance and the ID's 

 

Cheers,

Brett

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12 hours ago, Brett Breakin' Rocks said:

Rhinobatos sp. perhaps (?)

Fox_Hills_09_26_2020_Micros_003.thumb.jpg.0eee37834279aaa56f673106af4ca334.jpg

I think this one can be Plicatoscyllium, possibly P. antiquum. Your other tooth could be Palaeogaleus or Galeorhinus.

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27 minutes ago, Al Dente said:

I think this one can be Plicatoscyllium, possibly P. antiquum. Your other tooth could be Palaeogaleus or Galeorhinus.

Thanks, they are so small .. I appreciate the ID help. I've since found a few more specimens. I'll post additional images as I get them cleaned up and prepped. I'd love to come across some shark throat denticles or dermal denticles. Something I've never seen in person. 

 

Cheers,

Brett

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