One of my favourite recent posts on the Jordanian Lead Codices is this one from David Hamblin:
Jordan Metal Plates 4: Crocodile?
in which he suggests that a plastic crocodile might have been used to make one of the images.
For an excellent recent round-up of the issues, with links, see this post from Daniel O. McClellan:
Thoughts on the Jordan Lead Codices
and this one from Tom Verenna:
New Round-up on Lead Codices and Additional Information