Chevron bones known in Oreodon tails?

[Martin Dammann]

Whilst preparing a Merycoidodon culbertsoni that I found in 2012 in the Lusk/Wyoming area I discovered several small bones between and seemingly underneath the caudal vertebrae all along the tail.
The bones in question appear between 5 different caudal vertebrae and decrease in size. 
Here photos of the 3rd and 5th bone. The 5th and smallest bone is situated between the 10th and 11th caudal vertebrae.
The specimen is from Whitneyian layers. 
I could find no evidence of such bones in the literature available to me.
I would be interested to know wether such bones (chevron bones?) are known from Merycoidodontinae.
Thanks a lot.
Martin Dammann

Attachments:

You must be logged in to view attached files.

[Eleanor Gardner]

Hi, @martin-dammann!  Interesting find!  Although I’ve done field work in the Lusk, WY, area, I don’t have much knowledge of oreodont skeletal morphology.  Perhaps @bmacfadden, @smoran, or @sue-hirschfeld could help you out.  What do you all think?

[Bruce MacFadden]

@martin-dammann

@egardner

 

Hi–

The skeleton is beautiful and the chevron bones are interesting.  I am not aware about reports of these. Let me do some hunting and looking at references. I will let you know if I find something. Is it OK with you if I cut and paste your photo(s) and send them to someone who is a better anatomist than I am?

[Bruce MacFadden]

I have now consulted  textbook of veterinary anatomy (Sisson and Grossman) and read the sections about skeletal osteology. There are no reports of accessory chevron bones in the caudal vertebral series. Are you sure that the extra bone in question associates with the tail vertebrae, or could it be from another source, like a fragment from elsewhere in the fossil?

[Martin Dammann]

Hello Mr. MacFadden. Thank you very much for this information.

The fossil is prepared and visible from above. There are some foot bones of the hind legs that have fallen off and drifted a bit, but they are in higher niveaus of the rock.  At this time the tail must allready have been fully covered. All other bones are in the original position. I have found no remains whatsoever of other animals associated in this rock.

All this makes it unlikely to me that they are drifted bones or fragments from other parts, yet of course if there were chevron bones at any joint some must have drifted or ly underneath the vertebrae.

I add a photo of the entire tail with the marked bones and details of the small bones 1, 2 and 4. Bone 3 and 5 are allready depicted.

Please do show the photos to a colleague if helpfull.

Attachments:

You must be logged in to view attached files.

[Bruce MacFadden]

This still baffles me. I’ll keep looking. Your photos are very clear and they are very helpful. If I find something out, I will let you know.

[Martin Dammann]

I would be very gratefull on anything you can find out. I realized I can fineprep some parts a little bit more.

[Bruce MacFadden]

Martin–Yes, I will keep trying. Bruce

[Author]

Posts