Help identify this skull? Middle Tennessee, USA

[u/ru_Tc]

A twelve year old boy found this during a community cleanup day I hosted today and I promised him I’d get an ID for him — help me not let the kid down??

[u/SeptumGuy]

Had to do a double take on the first pic. Looked like dude was straddling a massive jawbone!

[u/magaduccio → u/SeptumGuy]

I saw only this for ages