Fossil Friday!

This week on Fossil Friday, I give you an incredibly easily identified fossil. I mean, come on, it's the whole body!  Plus, I'm going to tell you it's a synapsid from the Permian. What could be easier?

But I do have some additional demands. You must tell me not only what species this critter is and where it was most likely found, but also provide a layman's explanation of what a "synapsid" is. First person to explain this to my satisfaction wins bragging rights for the week!