What cut of beef is this?
The photo on the left, specifically the upper left quadrant appears to have a concave shape that would make one think (at first glance) of the short ribs, but the ball joint and size definitely is the give away here. Assuming the dish it rests in is an 9x13 casserole dish you are right that this is probably from a lamb rather than a beef. But the folks at Victorian Farmstead provide a photo that makes it completely clear that we are indeed looking at a "Bone In Leg of Lamb"