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Spine-shaped marine fossils from Upper Cretaceous of New Mexico


Jeffrey P

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I found this sandstone slab last week when I was out collecting Upper Cretaceous marine fossils with Mike and Brian in the Rio Puerco desert northwest of Albuquerque, New Mexico. I have no idea what the spine-shaped fossils are. Any feedback would be appreciated.

IMG_4751.JPG

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I do not know, but My first thought is spines from an ammonite shell. 

Second thought is some strange gastropod.

 

Tony

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What do the ends look like hollow, solid, a calcite cleavage plane, filled in with sediment, etc. What fossils did you find nearby?

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5 hours ago, DPS Ammonite said:

What do the ends look like hollow, solid, a calcite cleavage plane, filled in with sediment, etc. What fossils did you find nearby?

They appear solid, not hollow. Fossil assemblage includes bivalves, teeth of shell crushing sharks, and ammonites.

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They don't look quite right for sea urchin spines.  There seems to be a bit of a curve to them and sea urchin spines are straight.  The base and texture also doesn't look right for them.

 

There are shells that have spines on them but these don't look like any that I'm familiar with.  The one shell with spines that I'm most familiar with is the spiny jewelbox and while they curve you can see a seam along one edge of the spine.  I can't see a similar seam on any of your spines.  That doesn't rule out shells, it's just not one I've seen before.

 

Kara

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Ho,

 

OK with Kara : not a sea urchin spine. This one is broken on its end and generally sea urchin spines are in calcite. When they are broken, the plan of split (cleavage) is never perpendicular in the spine...

 

Coco

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Could these be some kind of scaphopod?  I've only collected the ones from older strata so I don't know anything about cretaceous species.

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I doubt that much older Tentaculites would survive much reworking to be included in Cretaceous rock. I favor Bob's idea that it is a scaphopod which are found in Cretaceous rocks. Another careful look at the larger ends of the fossils might reveal that they were originally hollow and now filled with rock.

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Jeff, can you show photos of other views of the rock?  Anything else in it that you recognize?

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@Jeffrey P I cannot help with i.d. on these though I did want to give some more information if you choose to continue your search.

 

This sandstone layer is the upper calcarenite of the Juana Lopez member of the Mancos shale and is lower upper Turonian in age. The impressions of the ammonites Prionocyclus wyomingensis  and Scaphites whitfieldi can be found in this same layer. 

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Go Jeff! neat finds and congrats on getting out of NY for a change to collect!

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  • 3 months later...

@Jeffrey P, I asked a couple folks at the museum about these mystery fossils and received these replies...

 

"The calcarenites of the Juana Lopez are composed of mostly bioclastic debris which originate from the fragmented prismatic layers of Inoceramus."

 

"I think they are large shards of inoceramid shells, with thick prismatic calcite composition."

 

...which follows suite with what I could find in literature. Personally, I think they are too uniform to be called shards and will keep it as a problem to be pondered.

 

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I could see the whole ensemble as crinoid remains. Maybe those in question are crinoid spines. I just don't see inoceramid fragments.

I know, the geological age is different, also the location, but the dimensions could vary. Please take a look at this plate from here .

...or maybe they are from gastropods ? :headscratch:here

Platyceras-spines-and-Acanthocrinus-Crinoid-spine-fossils-Devonian-Period--Jeffersonville-Limestone-Jefferson-County-Kentucky.jpg

 

 

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Yes... Inoceramid fragments.  We get those up here as well.  The crystal patterns go perpendicular to the length of the thing.  Scaphopods have texture that goes parallel, and are much more regular in their tapering.  These are not a smooth transition.  Inoceramids.    

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I'm not sure about the fragment thing either, (unless that means the spines?) but agree it could be parts of a bivalve. Based on age and location I'm thinking some kind of Spondylus?

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