Pelycosaur material need help

[Le Quoc]

I got these material from one seller. The information that I have is these all come from Oklahoma, USA. I have separate and glue some. I put them in 2 group that which have spike and which doesn’t have. It very pleasure that you could help me to ID them! Thanks! 
 

First group

 

 

 

 

 

 

 

 

 

 

Second group 

 

 

 

 

 

 

 

 

Edited July 19, 2021 by Le Quoc

[ThePhysicist]

Haha, I remember seeing this listing. I'm not going to go through each piece as you've already noticed two kinds. They are all neural spines likely from Edaphosaurus sp. and Dimetrodon sp. 

 

Edaphosaurus has the "spikes" you mentioned, Dimetrodon has none and is "pinched" in the middle like so:

 

^https://doi.org/10.1007/s00114-018-1598-1

[jdp]

Yeah I see both cf Edaphosaurus and cf Dimetrodon there.

[Le Quoc]

On 7/20/2021 at 1:09 AM, ThePhysicist said:

Haha, I remember seeing this listing. I'm not going to go through each piece as you've already noticed two kinds. They are all neural spines likely from Edaphosaurus sp. and Dimetrodon sp. 

 

Edaphosaurus has the "spikes" you mentioned, Dimetrodon has none and is "pinched" in the middle like so:

 

^https://doi.org/10.1007/s00114-018-1598-1

Thanks for your help! But there are a lot species of pelycosaur, how to identify exactly for It? 
I have just make a thin section of one bone from the bunch that you said Dimetrodon.

 

[ThePhysicist]

Wow, that thin section is really cool! 

 

To my knowledge, there is no diagnostic feature on Sphenacodontid neural spines that allow one to identify them down to a species. Given the locality, D. limbatus is a possibility.

[Le Quoc]

18 minutes ago, ThePhysicist said:

Wow, that thin section is really cool! 

 

To my knowledge, there is no diagnostic feature on Sphenacodontid neural spines that allow one to identify them down to a species. Given the locality, D. limbatus is a possibility.

Thank you. They are come from Wauriika sites, Jefferson county, Oklahoma