Permian Pelycosaur Appendicular Bone

[Opabinia Blues]

Here’s a pelycosaur appendicular bone I acquired from a vendor well-acquainted with Permian material a while back. It was sold to me only as Dimetrodon limbatus from the Archer City Formation in Texas. Thing is, I’ve never been able to place exactly what bone it is, and it doesn’t seem to match any appendicular elements of Dimetrodon which I could find references for. Here’s to the hope that there’s somebody here well-acquainted with this material who can put me on the right track!

 

 

 

 

[Opabinia Blues]

Should give an update here:

 

I had someone I know who’s familiar with material from this locality look at this bone, and the answer is that is apparently a Trimerorhachis femur. So not pelycosaur at all, and a serious misidentification from the original owner of this fossil.

[hadrosauridae]

very nice!

[Carl]

@dinodigger

[jdp]

Femur is correct. Trimerorhachis is not. That is Archeria. It is too short and stout for Trimerorhachis, and the broad U-shaped distal concavity is pretty conspicuous for stem tetrapods like Archeria.

 

See the below figure from Romer (1957)

 

Full paper here:

https://deepblue.lib.umich.edu/handle/2027.42/48305