A couple of mysteries from the Peace River

[digit]

Finally got out last Saturday to take advantage of the Peace River finally cooperating with us fossil hunters. Had a good day with lovely weather and a few new friends with whom we tried to kindle the passion for fossil hunting. If you missed it, you can catch-up here: http://www.thefossilforum.com/index.php?/topic/64534-peace-river-huntfinally-april-2016/

I didn't keep too many fossils from the trip (though among the keepers were two sizeable chunks of mammoth molar). Most of the things I found were easily identifiable but then I was left with two that were beyond my (current) knowledge. Any help with these would be spectacular. Here is the descriptions from my previous trip-report post:

Then there is this smaller piece of turtle shell. I found a surprising number of proneural plates at the first site (at least half a dozen) which I gave away to various folks on the river. The proneural (also often called nuchal as the nuchal scute overlays this bone) is the bone is the bone at the front of the line of neural bones that run down the midline of the turtle's carapace. See these images for examples of these distinctively shaped bones: https://www.google.com/search?q=turtle+nuchal&tbm=isch

The piece shown below is obviously symmetrical and so must come from the midline of the shell. At first I thought it an odd proneural/nuchal imagining the head and neck sitting in front of the scalloped edge at the "top" of this piece but the more I look at it I just can't seem to fit that into my understanding of the bones that comprise a turtle carapace. I considered it possibly being from the plastron instead but could not seem to find any matching bones with this overall shape. My current guess is that this might be a suprapygal bone from behind the line of neurals rather than leading this series of bones. If there is anybody out there with a better understanding of turtle anatomy than this novice, I'd appreciate your opinion on this little mystery.

Here is the last mystery from this trip. An odd bone with an unusual lumpy texture on one side. I initially thought this might be some sort of epiphysis--the end of a long bone separated from the main portion of the bone by cartilage in younger animals (later fused to the main bone in adults). The other side of the bone looks more worn (you can see the exposed cancellous texture. Given the round overall shape the thought of some part of a vertebra comes to mind but I can't seem to make much of this one. If someone has seen something like this before and knows its true identity, I'd welcome being informed.

Cheers.

-Ken

[digit]

No takers yet? I've emailed images of these to Dr. Richard Hulbert at FLMNH to see if he has an opinion. He is busy at the moment with the last couple of weeks of fieldwork at the new Montbrook site but maybe I'll catch him with a moment of time to spare and get some insight on these two finds. Meanwhile, if these look familiar to anybody out there--I'm all ears.

Cheers.

-Ken

[digit]

Dr. Hulbert has weighed in on the turtle piece and confirmed that it is a suprapygal from one of the Emydidae, likely Pseudemys (one of the freshwater cooter turtles).

The brown item remains a mystery.

Cheers.

-Ken

[tmaier]

Is it still valid to use the "Chunkosaurous" label, even when the source is likely from a mammal?

I'm no vert expert, but doesn't that rounded part look like a ball joint?