A much less usual white lias formed part Ichthyosaur femur or possibly humerus.

 From the Penarth coast south Wales, well known for it's exposed Triassic bone bed & fossils from the late Triassic & early Jurassic

Please view the images for the size 

If you have time check out my other vintage, antique rare & unusual listings. I often have coprolites & the occasional fossil too. 

Good luck & happy hunting