The story of burying the skin (not the whole goat) used to go around during the eighties, not sure how right or true it was though. I don't know the finer detail although I'll admit to a few attempts at making a bodhran during my teens.
There is some nice footage in the RTE archive:
-wrenboys and bodhran making from 1966
-Bodhran maker Sonny Canavan from 1977
there's the wellkown Photo of Thady Casey, with bells on and another one here, both taken at the 1957 Fleadh in Miltown Malbay. There are some great recordings of Willie Clancy and Aggie Whyte playing with Thady drumming away, recorded by Seamus Ennis in 1962 for BBC, in Marty Malley's house.
The image of the wrenboys is a very wellknown pre-O'Riada one. As is this later one
There's a lot more of that stuff, lovely photos taken for the folklore commission, as it was then, and if you go deeper into the iconography, the bodhran/tambourine occurs in several 19th century images.
And the Tom Morrison/John Reynolds 78rpms are definitely pre-O'Riada.