Knightia and what else?

[allen.wallace]

This fish fossil is from the Green River Formation, These fossils are enclosed in a thin layer of shale. The vertebrae are 33mm long, possibly Knightia? On the left upper edge of the rock is a fin.  I had a x-ray taken and I see several straight pin shaped ribs? However they are a poor match for ribs described in "Paleontology of the Green River Formation, with a review of the fish fauna" (Grande, 1984). These "ribs" are very straight. There is also the central rod-like thing, which is perhaps plant material? 

 

I thought a X-ray would review hidden secrets, but it hasn't really adding anything I couldn't see with my naked eye.

 

This forum is a joy to browse. I'm very appreciative of the responses I've gotten from my previously ID requests so far. I am certainly learning! 

 

Any ideas as to what I'm seeing?

[Fossildude19]

Allen,

The entire bit of matrix is only about  2"x 2", correct? 

The straight, "pin shaped ribs" are not ribs, but rather, I would suggest they are disarticulated anal fin pterygiophores, or fin bone supports, of a larger fish.

Maybe something like a larger Diplomystus.  They have fairly straight anal fin supports.

 

The vertebrae could belong to a Knightia, but I would also not rule out a larger fish.

I only counted 9 or 10 (hard to be sure due to picture quality).  

33 mm equals, roughly, 1.25 inches. They could belong to anything over 2 inches or so. 

 

The solid item is a bit more problematic.  I don't think plant, as they are usually compressed, and not 3 dimensional, as this item is. 

It could be a part of a bone from a larger fish or animal, but could also be a dorsal or pectoral spine from one of the catfish of the Green River Fauna. (Hypsidoris farsonensis, or Astephus antiquus.) 

The shape also bears resemblance to the thickened bones located between the head and dorsal fin on a Diplomystus dentatus.

See attached image from  Grande, 1984.

 

 

 

 

Hope that helps. 

Regards,

[Auspex]

55 minutes ago, Fossildude19 said:

Hope that helps. 

This is not just informative, but vastly informative. Well done, Tim!

[Auspex]

11 hours ago, allen.wallace said:

I thought a X-ray would review hidden secrets, but it hasn't really adding anything I couldn't see with my naked eye.

Nonetheless, it is very interesting!

[Tidgy's Dad]

1 hour ago, Auspex said:

This is not just informative, but vastly informative. Well done, Tim!

Is this a clue that we're going to have a "vastly informative" button added on the next update ? 

[Auspex]

2 minutes ago, Tidgy's Dad said:

Is this a clue that we're going to have a "vastly informative" button added on the next update ? 

Just click it real hard.

 

Tim's is much more than just an answer, it is an explanation packaged with detailed information in a way that makes sense.
I wish we did have a "V/I" button for such!

[RJB]

  Im begining to understand that Tim is probably worth more money.   However much he's being payed,  I say we give him a raise.  

 

RB

[Fossildude19]

Thanks Ron.   

I get much more out of the Forum than I give. 

I just have a good answer, from time to time.