Reading about "Black Dog"

I'm reading one of my BIRTHDAY gifts -- a book-length examination of the UNTITLED FOURTH ALBUM by LED ZEPPELIN.
It's well-written, but I wouldn't expect anything less from author BARNEY HOSKYNS. I have previously read his history of The Band, "Across the Great Divide."
The first third or so of the book chronicles Led Zeppelin's formation and the first three albums.
I have reached Page 74 and a discussion of the surprisingly complicated first track on the fourth album, "BLACK DOG."
The song features a complex, shifting time signature. John Paul Jones originally conceived the tune in an impossible-to-play 3/16 time. It eventually was played as "a beat that's a count of five over a count of four, and trips and skips and stuff like that," Robert Plant said years later.
Hoskyns quotes John Reid of the Hampton String Quartet as saying the intricately complicated song actually has "something like 98 time-signature changes."
Not bad for a rock band, eh?
I like Led Zeppelin because they were such outstanding musicians. "Black Dog" shows what it was like when they were showing off for fun.