First prep of a Mioplosus(?) from Kemmerer, WY

[ScottM]

Hi all,

 

I had a great trip to Kemmerer this summer and have begun prepping some of my finds. Reading the previous posts in this forum has been extremely helpful - thanks! Until now I have only tried prepping Knightia and Diplomystus from a previous trip to the split-fish layer. They are fun and easy and relatively low stakes. This trip I had more luck getting larger specimens (still in the split-fish layer) and I decided to prep the fish below as a practice/warm-up before tackling my best find. I primarily used an Xacto knife, a sharpened dissecting needle, and some sharpened dental tools and employed the "stop and glue" method, with a 2-3% paraloid B-72 solution. I am happy with the outcome and learned a lot. There's some amazing detail visible that my smaller specimens don't have (see close-ups). Bummer about the caudal fin, but that how I found it.

 

My questions for those with more experience are:

1) Is it in fact Mioplosus?

2) Any idea what's going on inside the mouth? I know Mioplosus (if that's what it is) are known to sometimes die choking on their last meal. Could that be what's going on here or is it a piece of its own jawbone that got stuck in there? I tried to get a decent photo but it's much easier under my magnifier light.

 

Thanks!

ScottM

 

 

 

 

 

[Fossildude19]

Nicely done.

 

Yes, it's a Mioplosus labricoides.

 

I think it is more likely that the bone in the mouth is some part of this fish's skull. Something that was disarticulated or crushed down from the fish's own skull.

[Ludwigia]

Nice job! I tend to agree with Tim.

[snolly50]

Yes, Mioplosus. Nice prep and especially images. It's great to see clear, detailed photos.

[Randyw]

I agree with all the above! Great prep on the teeth! A very nice speciman!

[Ptychodus04]

Great prep on a nice Mioplosus. The bits of bone in the mouth are likely the left dentary. The bones of a fish jaw are connected by tendons to allow an extreme amount of flexibility in life. Mio's are closely related to modern bass which use suction feeding to catch prey. They do this by expanding the jaws to create a vacuum that literally sucks the water (with the prey) into their mouth.

 

On a purely pedantic note, the layer colloquially referred to as the "split-fish" is actually the Sandwich Beds. It gets this name from the ash layers directly above and below it. It is the oldest layer in the Fossil Butte Member, representing the start of the lacustrine deposits in "Fossil Lake". The actual layer named "split-fish" is the Upper Split Fish Bed. This is the youngest layer in the member.

 

The incorrect use of "split-fish" when referring to Sandwich Bed tends to create some confusion when speaking with people who know the geology of the Fossil Butte Member.

[ScottM]

Thanks, everyone! 

And yes, on closer look (and with the help of some diagrams) dentary seems right. 

Much appreciated!