Last weekend while walking with friends we found some strange bones. At first we thought it was a skull because there appeared to be eye sockets at the side, but there was a leg bone attached and a broken leg bone on the other side but with the ball joint still attached so it can't be a skull. On the inside the looks to be ribs. I thought it must be some kind of frog or toad, but the leg bones look very long, so yesterday I asked a very knowledgable friend who was stumped by it. A few others had a look and were equally baffled. We'd now all really to know if anyone can identify it. Photos are attached.